PRE-PRODUCTION/PREPARATION

OVERVIEW

Scott Squires

The making of a film, commercial, or television show is broken into three main phases:

Pre-production: where all the design, construction, and preparation occurs before any filming is done.

Production: the actual filming of the live action that occurs on a set or location.

Post-production: all the work to complete the project after the filming. This includes editing, sound, music, and visual effects.

Even though the majority of visual effects are done in postproduction to augment the shots that were filmed, all of these phases are important to visual effects. During production a visual effects supervisor or plate supervisor is on the set to make sure the live action is shot in a way that visual effects can be added correctly in post-production.

This chapter covers pre-production relative to visual effects. This includes the budgeting of the visual effects and the decisions about what company and visual effects team will work on the show. More importantly, it covers the designs and the techniques that will be used and that will ultimately determine much of the success of the visual effects. Pre-production is also a good time to develop new techniques, test ideas, and start the building of models when possible. Although this chapter approaches many of these areas from a feature film standpoint, the same steps apply to commercials and television production, just in a smaller number of shots and shorter time schedules. Each production is unique, so the issues covered in this chapter are meant as a starting point for a typical production. Budgeting requirements may be a bit different from studio to studio, and some areas, such as previs, are continuing to develop and change.

Production (producer, director, studio) may be reluctant to spend much time on visual effects pre-production, but this can have a huge impact on the cost and quality of the visual effects and the time required. A VFX Supervisor is able to work with the director, producer, and production departments to determine tradeoffs for different approaches. This may prevent the construction of large elaborate sets that could be replaced by matte paintings or the use of digital doubles for stunts that could be impractical on the location. The choice of techniques in pre-production will also determine what steps are required during shooting and what can be done to shoot as efficiently as possible. Pre-production costs are relatively small since a smaller team is involved. If design decisions are not locked in before filming, then it is possible the live action may be shot in a manner that will need to be completely changed in post-production when the designs are locked in place. This is not only very expensive but is unlikely to provide the best-quality shots.

BREAKING DOWN A SCRIPT—BUDGETING

Scott Squires

Budgeting visual effects is a difficult and ongoing process because of the number of unknowns associated with visual effects shots. Any assumptions should be listed on any bid, along with the date of the script and any additional materials (storyboards, etc.). Shots will have an average length assigned by default (usually 5 to 8 seconds).

To balance the flexibility of editing with the costs associated for animating and rendering visual effects, a “handle” length is usually assigned on a project. These are the number of extra frames at the start and end of each shot (typically 4 to 8). This allows the director and editor some slight adjustment in editing even after a visual effects shot is completed. Without this handle, many shots would have to be redone, which would cost more time and money.

The creative aspect of film production plays a major role in the ultimate costs of the shots. The design and style of the shots along with the decisions by the director will shape the budget requirements. Changes later tend to be much more costly than if the shots were designed and shot as planned.

Visual effects companies do the majority of visual effects work on feature films as fixed bids. Any miscalculation can be very costly to them. It is important to be as specific as possible and to budget a certain amount of creative freedom for the director. Change orders are created by the visual effects company when a shot changes so much that the costs have increased, but there should be some built-in budget tolerance to avoid having to issue a new change order on every shot daily.

Some small films may be done on a time-and-materials basis. The visual effects company provides an estimated budget but the actual cost will depend on the actual time required to complete the work.

Ballpark Budget

The first visual effects budget (ballpark, rough, or initial budget) is likely to be done before a director is even assigned to the film. The studio will have a script that it would like to get a rough budget for. A VFX Producer at the studio or an independent VFX Producer may do this initial budget.

The VFX Producer reads the script and notes any scenes that would seem to require a visual effects shot. In visual effects, each shot is custom done. The first step to breaking down a script is to determine the numbers and types of shots. A script, however, does not provide this information. Even a production script will be broken down only per scene, not per shot.¹

If a director is not yet involved in the project, then the VFX Producer will have to make guesstimates about the rough number of shots required in any given scene. This will be based on the VFX Producer’s experience and knowledge of film. A single scene can be one shot or a dozen shots. A rough rule of thumb might be a shot per sentence in the scene or per action verb, but once again this is very dependent on the writer and director.

A simple ballpark budget may be arrived at merely by taking the number of total visual effects shots and multiplying this by a shot average cost for this type of film. This figure could be based on the experience of the VFX Producer. Since unions do not cover most visual effects positions, there are no set salary levels. Actual rates will depend on the location and company hiring. A slightly more accurate approach is to assign shots to easy, medium, and hard ratings with corresponding costs associated with each. Another approach is to break shots into basic shot types (2D composites, 3D animation, matte painting, etc.) and related costs for each. Note that each of these costs would include all direct costs, overhead, and profit to provide the final figures.

The VFX Producer typically uses a spreadsheet or a database program to list the shots, with a brief description and the costs and totals of each. Any assumptions are listed in the final budget (i.e., “car crash assumed as stunt, with only rig removal required”).

More Detailed Budgets

Once a director is assigned to the project, the VFX Producer and VFX Supervisor will review the script and adjust the shot count and shot types based on the director’s thoughts. In some cases shots that were deemed to be visual effects may be able to be accomplished by other means on the live-action shoot (such as stunts or special effects²).

It is important for the other department heads to be realistic about what they will be able to achieve on the set or location. Anytime something does not work during the live action, it is likely to be added to the visual effects list of work to be done.

As the sequences are designed, they are assigned a two- or three-letter abbreviation per sequence. Shots are then assigned as three or four numbers within the sequence and frequently incremented by 10 to allow new shots to be added between planned shots. For example, RL010, RL020, and RL030 may refer to three shots in the rocket launch sequence. If a shot is added between RL010 and RL020, it might be designated RL015. These numbers are assigned to storyboards and previs so there is a one-to-one correspondence.

As sequences are storyboarded or prevised, they will be rebudgeted based on these. Rebudgeting is also required if there is a rewrite on the script that involves visual effects. A dozen or more revised budgets may be required over the course of a film.

Cost and time requirements are taken into account when determining techniques to be used. Any change in technique will require adjustment to the budget.

Bidding

At some point in pre-production, a package of identical material is sent out to various visual effects companies. This will include the script, any storyboards and previs completed, and a breakdown provided by the VFX Producer. The breakdown will list the shots, their description, and a defined technique, if any. The same information is supplied to all of the companies with the hope that the bids received can be compared directly to one another.

Depending on the show, bid packages may be prepared for specific sequences or types of shots and assigned to different companies that specialize in a particular type of effect. Some film projects are awarded to one visual effects company and some are split up among a number of visual effects companies. The latter approach is used when schedules are limited or production quality and costs are best deemed to be split among a few visual effects companies, with each doing a specific sequence or type of visual effect.

The choice of which visual effects companies will bid on a show depends on their availability and the studio’s experience with them. Location of the company is no longer the issue it once was.

The visual effects company has its own VFX Producer and VFX Supervisor review the material and create a detailed bid. This is usually done with the various department heads or leads when accuracy is desired. Each shot may be discussed and assigned a number of man-days per task (matchmoving, roto, compositing, etc.). Each of these estimates is placed into a spreadsheet and cost calculations are based on each particular task. By default, a profit margin and a small amount of padding are added to the total. These types of details, however, are not usually turned over to the studio; only the costs for the shots.

All model building, model shooting, element shooting, and other assets will need to be calculated based on time-and-materials estimates. The length of research and development (R&D) and the number of people involved will need to be noted as well.

Plate Photography³

Typically, a small team of visual effects artists is sent to cover the live-action shoot to make sure the shots are correct for visual effects use. This team usually consists of the VFX Supervisor, coordinator, and data collectors. These costs are billed on a time-and-materials basis to the studio.

The overhead or non-shot-specific costs (operating costs, support people, equipment usage, etc.) and assets (CG models, physical models, etc.) are usually broken out separately from the shots. If asset costs were folded into shot costs, then a change in the number of shots would be incorrectly budgeted.

It is important when bidding to make sure realistic numbers are gathered. Pressure from the studio and competition may produce a bid below the actual cost, which may get the project awarded but cause problems later if the work cannot actually be done for that amount.

Another problem in bidding is being too optimistic. Nothing will go as well as expected and even simple shots will take more time than anticipated. Do not budget for the best-case scenario.

When department heads bid a specific function, they should provide estimates based on their average team member and not themselves. Whenever possible, costs and times required for recent projects should be compared to the new bid as a reality check.

While bidding the costs, the VFX Producer lays out a linear timeline based on the amount of work. Visual effects production usually ramps up with the modelers and texture-painting artists starting first, along with the key department leads. Any R&D will have to ramp up as well. If the time required to complete the visual effects is longer than the production allows, then the visual effects company has to consider adding additional artists and workstations or they have to budget for overtime. The other option is to tell the studio that the company will be able to do only certain sequences in the time provided.

Live-action filming usually involves a 12-hour workday, 5 or 6 days a week. Visual effects production can be as low as 8 hours a day but is much more likely to be 10- to 12-hour workdays. Toward the end of the visual effects work, the amount of time required can skyrocket. The release date of a film is usually considered unchangeable, so time lost anywhere in the production has to be made up in visual effects. Ideally, the number of shots completed each week would remain constant, but usually there is a slow ramp-up. Concept or editorial changes can also pile up, requiring a lot of overtime work (90-hour workweeks or even longer) to complete the film. This is hard on the artists and provides the lowest quality at the highest cost. Unfortunately, this seldom is in the full control of the visual effects company, and those costs will have to be factored into the bid at some point.

Temp Screenings

For efficiency, shots are usually worked on in a preplanned schedule based on the turnovers⁴ and delivery schedule as well as resources and assets. The studios may have temp screenings and ask for temp versions of all shots or marketing materials for trailers, which causes a reschedule. This should be discussed with the studio before production begins and should be included in any contracts.

Reviewing Bids

Final selection of the companies will depend on the costs, experience, and quality of previous work. Tax incentives may also play a role in the decision. The size of the company will be taken into account since an expansion of shots could be problematic.

Contracts

The studio will draw up contracts with the selected visual effects companies. These should document the final bid along with the date/version number of any storyboards. The contract should also have specific dates for turnovers, the sequence completion dates, and the completion date. The completion date is known as the finals deadline. Due to time constraints, it is not unusual for large visual effects shows to edit and lock sequences for visual effects to begin even before the entire movie is finished being shot. So there may be multiple turnovers even while filming continues. Any key discussions or agreements should be put in writing if they will affect the cost or schedule.

Rebidding during Shooting

During live-action filming, changes are usually made that will have an impact on the visual effects. The visual effects team on the set should flag these, and it is likely the studio will want to rebid a sequence based on this new information.

Rebidding in Post

Once the film has been edited and the work is turned over to the visual effects companies, it will be reviewed based on the initial bid. Any changes from the original bid will require a change order from the visual effects company and a possible renegotiation of costs.

Monitoring the Budget and Schedule

During post-production the time each artist spends on a specific shot is recorded so the VFX Producer can flag when a shot is about to go over budget. The visual effects team needs to reevaluate the approach if a number of shots in a sequence are running over the original bids.

Typically, the number of visual effects shots for the film is divided by the number of post-production weeks available. This provides the average number of finals that need to be completed each week. This number is recalculated every week to reflect how many shots were actually completed the previous week.

Keeping the Budget Down

Creating visual effects is a complex task, with thousands of technical and creative decisions being made. It is a very time-consuming and labor-intensive process, which is the main reason for the high cost of visual effects. The number of people working on the visual effects can easily eclipse the number of live-action crew members. On a live-action shoot, the crew is visible and it is clear to the director and the producer that timely decisions are required. In post-production it is easy to lose sight of the fact that expenses are accumulating every day since the visual effects artists are busy working away at a different location from the director and producer. Here are some good practices to keep in mind:

•   Simplify techniques whenever possible.

•   Time and budget should be considered when determining techniques.

•   Avoid working on coming up with the ultimate universal solution if a simpler, faster solution can be applied to the shots in hand.

•   Work out any kinks in the pipeline before production begins.

•   Avoid miscommunication. Try to be as clear with the director and visual effects artists as possible to avoid wasted work.

•   Make large changes or adjustments to a shot early on. It is better to go too far and come back a bit than to do a dozen small takes to get to that same point. In many cases it may be necessary to go too far in order to determine the correct selection.

•   Start with the larger issues in a shot and progress to the finer details.

•   Do not wait until the shot is polished before showing it to the director. If there are changes to be made, it is better to make them early on. The exact point when a shot can be shown will depend on the specific director.

•   Get clean plates⁵ and as much data as possible during live-action photography.

•   Try to cast your visual effects artists to take advantage of their strengths on specific shots and sequences.

•   Keep an eye on the schedule. Avoid large bottlenecks in the workflow.

•   Try to keep the workflow moving and to anticipate and schedule elements and tasks accordingly.

•   Review shots in a cut sequence. Rather than looping a shot over and over again on a computer monitor, it is better to see it in the context of surrounding shots. This will avoid fixating on a small detail that will not make a difference in the final film.

•   Be clever with the number of visual effects shots and angles required to tell the story.

•   Avoid big changes when possible. Some change is expected in the creative process of making a film, but a big change can be costly.

•   Lock designs before the start of production. If a key design is not locked before shooting, it is possible the shots will need major rework.

•   Avoid unnecessary visual effects. If something can be done live or on a normal set, then do it.

•   Avoid “fix-its.” Visual effects are used more and more as a catchall to cover problems on the set that could have been avoided. These may not be major work, but they can add up quickly.

WORKING WITH THE DIRECTOR AND PRODUCER

Scott Squires

Before meeting with the director and the producer, the VFX Supervisor or VFX Producer should prepare by obtaining as much information about the project as possible. Is a script available? Who are the key people involved? What were their other projects? What is the project based on? Has the project been greenlit?⁶ A supervisor may be working for a visual effects company or may be freelance. Becoming familiar with past projects and any additional source material will make it easier to discuss the project requirements using these as references. If a script is available, it is best to read through it and make notes and questions in terms of the director’s vision and how the various sequences will be approached. The VFX Supervisor will have to consider some of the techniques required to accomplish what is described in the script.

Demo Reel

Before the meeting a demo reel and resume/credit list should be submitted if there is time. The supervisor should bring the same reel and multiple copies of the resume to the meeting. The following information applies to other visual effects artists as well. The demo reel should include only the best work and should be on a DVD that is no longer than 5 minutes (2 to 3 minutes may be a more useful maximum). The DVD case cover should include the artist’s name, position, and phone number. The inside flap of the DVD case should list the scenes or films in order and what the artist did or what their job role was. The DVD itself should also include the name and contact information since it may become separated from the case. A supervisor can usually just include the finished shots. A visual effects artist should include the before and after versions of key shots. Normally, this is done by showing the finished shot, then the original plate, and then the finished shot again. It’s not necessary to show a before and after for every shot. Customize it based on your job type (i.e., an animator may want to show an animation test for a shot). The DVD should include the name (and possibly contact info) on the main menu. Avoid showing running footage in the DVD menu screen so that when the reviewers see the shots, the images are full screen. Consider using movie music as a basic soundtrack, which the reviewers can listen to or not. Any music that is considered grating should be avoided. Do not take credit for work you did not do and do not falsify anything on your resume. The facts will be uncovered during the project and will make things very difficult moving forward.

The Meeting

The meeting with the director and producer is both a job interview and, it is hoped, a meeting of the minds. They will want to determine if the VFX Supervisor can provide the creative and technical expertise needed for the project and whether they feel they can work with this person for 6 months to 2 years, depending on the scope of the project. Does the director feel that he or she can speak in creative film terms and not be caught up in the technical requirements? Does the producer feel that the supervisor has the experience and organizational skills to oversee other artists and companies? They will also be evaluating how passionate the supervisor is about the project.

The supervisor needs to be confident and part salesperson, as with any job interview. One of the first questions will likely be how they can do a particular type of effect for a sequence in the film. The exact answer to this may be very dependent on learning other details of the project, but they will want to know the supervisor has answers and can work with them on determining the best solution for their needs. The supervisor will want to determine the scope of the work, the general look and approach the director is planning, and as many details as are reasonable in an hour meeting. The supervisor needs to evaluate the director and producer and the project as a whole to determine whether it is a project that the supervisor wants to commit to for the next year or two. There is no guarantee when the next potential project will be offered to the supervisor, so that will have to be considered as well.

Moving Forward

Once the supervisor is selected, the first issue will be determining the true scope of the work with the director, producer, and VFX Producer. A detailed breakdown will have to be done for budgeting, and this budget will have to be adjusted as storyboards and previs are completed. These breakdowns may be sent out to multiple visual effects companies to bid. The supervisor should work with production to make use of as much pre-production time as possible. There will never be enough pre-production time, so it is important to schedule storyboards, previs, designs, and tests to be done. The supervisor needs to be able to communicate clearly to both the director and to others what will be required and how they can strike the right balance of creative design, time, and budget to accomplish the visual effects. The supervisor may have to do mock-ups and work with other artists who can produce designs and mock-ups to try to refine the specifics.

If the director has worked with visual effects before, then the supervisor will have to explain any differences from other approaches that were used on the director’s previous projects. If the director has not done visual effects, then the supervisor will have to explain the basics of the process and what the director will need to know (without getting tied up in the technical details).

The supervisor needs to support the director with creative suggestions on shot design, creature design, and other visual effects creative issues. The approach many directors take for their visual effects shots differs from that taken for their other shots, but it is important to design the shots to match as if the objects and scene actually existed during the shoot. The supervisor will work with the director and producer to determine the best approach needed for the visual effects. This includes how to dovetail the visual effects into the design and execution of the film to achieve the best results within the budget. Planning how the elements will need to be filmed during production will be one of many issues the supervisor will have to convey to the director and the key production departments. When the director and supervisor work together well during pre-production, they develop a shorthand for communication, and the supervisor can use their understanding of the direction to guide decisions in production and postproduction.

It is important for the director to look at visual effects as a required art, not something to be feared or ignored. The supervisor should be looked on as a key part of the creative production team, the same as the director of photography. The director’s and producer’s support of the supervisor will go a long way toward making the filming of the visual effects elements easier and more productive. The first assistant director and the production manager will take their cues from the director and producer, and if plate photography is rushed to the point of compromise, then the finished visual effects will be compromised as well.

PRODUCTION DEPARTMENTS

Scott Squires

Production Design

The production designer works closely with the director, director of photography, and VFX Supervisor to develop the overall look of the film. The production designer oversees the art department. An art director supervises the construction of sets and modifying locations. The set decorator is responsible for the decoration of the sets, and the property master deals with all things that the actor will have to handle. The art department also includes production illustrators, concept artists, and storyboard artists. Vehicle design falls under the art department. Creature and character design is usually done by specialists brought in by the art department.

The design and the look of the film have a large impact on the approach and techniques employed for visual effects. The production designer and VFX Supervisor will work closely to determine the trade-offs of set construction or location modification versus using visual effects (matte paintings, models, etc.). Cost plays the largest role but time, stage space, and interaction requirements are also considered. Note that production may have production costs in a different budget than visual effects, so it may not be a direct correlation between the two. In some cases just a small area will be constructed that covers the majority of the shots in a sequence. Anything beyond this would be done with visual effects extending the set or location.

The art department creates a number of concept art studies in pre-production for the director and the studio to review. Once this concept art is refined and approved, it will be used by the visual effects artists as both a reference and a guide. This applies to matte paintings and virtual shots (shots created entirely in the computer or as a miniature) as well. If a visual effects company has its own art department, that group will work closely with the production designer in addition to the director and VFX Supervisor.

The visual effects team gathers additional references of the sets and props that will have to be matched or re-created in computer graphics or as miniatures. That includes specific photos for texture mapping, photos for reference, and measurements of the set. Blueprints are gathered for any sets and props, but be aware that changes can happen during the construction that are not reflected in the blueprints. These days, the art department also uses 3D graphics programs that facilitate the transfer of CG models between the art department and the visual effects team. These may be used as a starting point for the fully rendered models to be used in post-production.

Many of the same CG models of sets, locations, and props from the art department can be imported and used for previs. In this case the scenes and camera placement can be much more accurate and will reflect the final shot very closely. The art department plays a pivotal role in storyboarding and previs. More specifics on storyboards and previs appear later in this chapter.

Camera

The camera department consists of the director of photography⁷ (DP⁸) and a crew of camera operators and camera assistants. The DP is in charge of all photography, including lighting and composition. The gaffer, head of the electrical department, works very closely with the DP on the lighting. Whatever is captured by the camera system (film or digital) will be used as the basis for the visual effects plates and will also be used as a look reference for any virtual shots. The VFX Supervisor should work with the DP, director, and production designer regarding the format and look desired since these will have a direct impact on the visual effects and post-production pipeline. With the use of previs in pre-production, some DPs are starting to rough-in lighting designs even at this stage. These designs provide them with a guide for lighting the real sets. This information will be useful in the post-production phase if the lighting design remains consistent.

The VFX Supervisor should discuss a number of issues with the DP. Some of the issues include film format, capture media (film/digital), color correction, and special equipment requirements (repeatable heads, etc.). The overall look of the images and any required VFX shooting tests should also be discussed.

Camera Operator

The VFX Supervisor will work with the DP and camera operator on the set to let them know the framing requirements for the shot since there may be creatures or objects that will be added later.

Camera Assistant

The VFX Data Collectors will work with the camera assistant on the set to record the lens and exposure information for each shot and take.

Special Effects

The layman frequently uses the term special effects to refer to both visual effects and special effects, but these are distinct areas in filmmaking. The SFX Department handles special requirements on the set, including effects such as fire, rain, snow, explosions, breaking glass, and special props or set pieces such as a boat mounted to a motorized gimbal on a stage. Special effects are dealt with on the set during production, whereas visual effects are usually done to the images in post-production. Special effects are sometimes referred to as practical effects or mechanical effects.

The visual effects team needs to work very closely with the special effects team. In some cases the finished shot could be done either way. In those instances a number of factors will determine which approach should be used. Using special effects on set has the advantage of interacting naturally with the sets, actors, and lighting. Once it’s been shot and approved on set, the shot is finished. There are times, however, when safety issues, timing issues, or just on-set time are limited to accomplishing these types of shots at the time of shooting.

A more common requirement is for the special effects team to work together with the visual effects team. Special effects provides what it can on set for interaction, and visual effects adds to it with CG or other methods in post-production.

In pre-production the VFX Supervisor would work closely with the special effects lead and discuss the requirements on a shot-by-shot basis. This allows the SFX Department to build and test any special devices or rigs. A rig may have to mimic the shape and size of an object that will be added later with visual effects. This is known as a mandrill and could be an object covered in blue or green if it involves screen work. In some cases it may be something as simple as supplying a fan to produce a slight breeze to blow an actress’s hair in front of a green screen.

Visual effects frequently need additional photographic elements to add to shots. These may be torch fires for a matte painting, an explosion to replace a spaceship, or a puff of dust used to represent a large creature stepping in dirt. All of these involve the SFX Department and may be done some time during production or post-production as a second unit or separate visual effects element shoot.

Stunts

The stunt department is in charge of any risky action that would involve an actor or stunt person. Some shots could be done either with stunts or visual effects. A man being thrown across the street or a truck being flipped over could be done on the set by the stunt department or could be done by visual effects as digital animation or, as in the case of the truck, optionally as a physical model. In pre-production the director and production team will discuss the shot requirements with stunts and visual effects to determine the best solution. All shots that involve stunts will be reviewed. There may be certain physical limits on a real stunt that require a visual effect or at least completion of part of the shot as a visual effect. When it is possible to do the stunt on the set safely and in the way the director desires, that is usually the first choice. In many cases it may be a mix of techniques for a sequence, with some shots being done totally with stunts on set intercut with digital stunt people animated in other shots. Visual effects may have to create a total digital stunt double or may just do a replacement of the real actor’s face over the stuntperson’s face.

Flying people or animals in front of a green screen will require the stunts and special effects departments to provide the harnesses and wire work required to move them around.

Even simple stunts may require rigs that will need to be removed by visual effects in post-production. These may be wire rigs, ramps for cars, or small trampolines for stunt people.

Wardrobe

The wardrobe department is in charge of designing, creating, or obtaining costumes for all actors. Visual effects and wardrobe will discuss any costume issue that may affect the other department. The choice of bluescreen or greenscreen photography is mainly influenced by the colors needed for the costumes and wardrobe of the actors.

The VFX Supervisor will want to check any of the costumes that may need rotoscoping or keying against a colored screen. Thin veils, small tassels, and extra-shiny material such as foil could present problems in the compositing stage. These issues are discussed with the intention of coming up with a solution that will balance the creative choices with the cost, time, and quality required in visual effects.

If a digital version of an actor is required, the actor will likely need to be scanned in the specific costumes, so this will need to be scheduled accordingly. When possible, another copy of the costume is sent to the visual effects company so the modelers and the texture painters can use it as a reference instead of relying only on photos. A digital version may present some challenges of its own. If a costume has numerous dangling strings, these will have to be built and will require simulations to re-create the correct motion when the digital actor is animated. This will have to be taken into account when budgeting. In some cases the costume may be augmented with visual effects such as adding flapping wings or animated gadgets. In this case the wardrobe department would work with the director and VFX Supervisor (and likely the art department) to determine the look and requirements.

Occasionally the wardrobe department may create specific costumes for visual effects use, such as a motion-tracking suit or greenscreen suit. If an actor will be flown on wires or rigged to a special device, wardrobe will need to modify a costume to accommodate the harness by making parts of it slightly larger or by cutting the costume at specific points.

Makeup

The makeup department handles the hair and makeup for the actors. Specific makeup people may be assigned to specific actors. For elaborate prosthetics or unique makeup, a specialist may be brought in. If visual effects is required to augment existing makeup, then visual effects will need to work closely with the makeup department to determine how and where the visual effect will be added. It is likely tracking markers will have to be applied to the actor’s face using self-adhesive dots or by applying a spot of colored makeup. This will aid in the process of making sure the computer graphic face augmentation or face replacement will look like it is locked to the actor.

If a digital version of the actor needs to be created, the hairstyle chosen will have an impact on the shots. Special software tools may have to be written to style the CG version of the hair to match and simulate the motion of the hair, especially if it is an elaborate or long hairstyle.

Special contact lenses may be used for the actor, or production may ask for any special eye changes (different colors, simulated blind eye, animal eye, etc.) to be done as a visual effect. These types of shots can add up quickly and do take some work to do correctly.

The supervisor will ask the makeup department to keep an eye on visible tattoos that the director doesn’t want to see in the final film and any other cosmetic issues, such as wig netting, that can be dealt with on the set rather than in costly paint-out later.

Production

The production department includes the producer(s) and a number of support people. There may be line producers, production managers, and executive producers, depending on the film. Directors and their support teams are also covered under this department. When changes occur during the course of the production, it will be important to notify the producer so that adjustments can be made and to obtain permission to make such changes. This is very important if the changes have an impact on time or budget.

One of the other key production people who will interact with visual effects is the first assistant director.⁹ The 1st AD is very much involved in the scheduling of the daily shooting calendar and in keeping production shooting on the set. The VFX Supervisor will want to check the shooting schedule for any visual effects conflicts. The 1st AD is a key link in making sure that visual effects has the time necessary to get what it needs on the set, so it is important for the VFX Supervisor to work closely with that person and to have them as an ally. All visual effects shooting requirements should be made clear in pre-production so that the 1st AD can consider the extra time required and can help facilitate the shooting of references and data gathering when the shoot starts. Without the support of the 1st AD, shooting visual effects shots will be problematic and could ultimately have a large impact on the cost and time required to do the visual effects.

Visual Effects

While the various departments are getting prepared for production, the visual effects team should take as much advantage of this time as possible and be proceeding with their own pre-production. The intention is to lock as many of the concepts as possible and to accomplish any work that does not require the team to have finished footage in hand.

Planning

During pre-production the VFX Supervisor should be getting a better idea of what the director is looking for in the completed film and how the director likes to work. That, along with the concept art, storyboards, and budget, will influence the techniques chosen by the supervisor. It is important to reevaluate the approach to make sure it follows any changes in the design and look of the shots.

Testing

During pre-production tests often need to be done to resolve a problem or check a technique or look before filming starts. This needs to be scheduled and budgeted since it could have a large impact in the coming production phase.

R&D

A film project may require developing new techniques, software, or pipelines. That work should begin in pre-production since it can be time consuming to develop. If it is to be used to create a special look for the film, the director and studio may need to see it before moving forward with the project. The VFX Supervisor may need to work out a new technique before shooting begins to confirm it will work as expected, to fine-tune the process, and to determine the requirements for filming.

Reference Materials

Footage and images should be gathered as reference for the visual effects artists. This might be videotaping an animal at the zoo or reviewing other movies or photos. Reference material can be used as a starting point for animation, modeling, matte paintings, and lighting. The material is also useful to share with the director and other department heads such as the production designer and the director of photography. With clear imagery and references, it is possible to narrow down what works visually for the show and what does not.

Direct references will also be required. This includes shooting both reference photos and texture photos for any props, sets, and costumes that will need to be re-created in computer graphics. It also includes scanning the actors and props for 3D models. Once shooting starts it can be difficult to schedule the actors, and any delay in getting this information will delay the construction of the models. Note that the actual props or costumes may be modified in the first week of shooting since everything will be reevaluated on set.

Modeling

As soon as designs are approved by the director, physical and computer graphics models may be started. If these need to tie in with actual production (such as a set), they may need to be delayed or at least be done with enough flexibility to change based on the live action. As modeling proceeds the director will be shown the work at different stages to get his approval and adjustments. If the model is to be used for animation, a rough version may be used to start experimenting with the animation and exploring the character.

Editorial

An editor works with the director to take the raw footage that has been shot and assemble it into the finished film. A film that has a large number of visual effects shots will likely have a VFX Editor or Assistant Editor. The VFX Editor will be writing up the

information shot sheets for the visual effects companies and cutting in shots in progress during post-production.

Although most of the editorial work will be done in post-production, the editor may actually start during pre-production. The storyboards can be scanned and assembled to provide a rough sense of the action and timing. As previs becomes available, it will replace the storyboards. The editor may also assemble rough sequences of “scrap” material made up of action sequences from other films to use as a template.

Scheduling may require the editor and director to complete the editing of specific scenes even while still shooting others so that the visual effects can be started. The visual effects editor and visual effects company may both be doing mock-ups to be cut in as the edit proceeds.

One of the issues to be discussed with the editor is the choice of format for the visual effects footage delivered for review. This may require the visual effects company to output a specific file with an applied color correction so that it works in the sequence on the editing system.

The editor will also work with the post-production supervisor and the VFX Supervisor to determine the requirements for the visual effects delivery. Some of these issues would be

•   film or digital or both,

•   format for delivery,

•   method of delivery,

•   digital intermediate (DI) requirements,

•   any alternate deliveries (versions for television framing, etc.),

•   schedule for DI or lab color correction,

•   schedule required for temp screenings,

•   schedule required for music and sound work that might require finished shots, and

•   schedule for final deliveries and in what order of sequences.

Locations

Location Scout

During pre-production the production department and the production designer will have a location scout¹⁰ searching for appropriate locations. The VFX Supervisor will want to discuss the requirements for visual effects at these locations. If they have a large impact on the visual effects, the VFX Supervisor may be asked to review the actual location or to review multiple locations to determine which may be best for the particular sequence. Which things will need to be added or removed in post-production to get the shots required? The VFX Supervisor will need to flag things that are not an issue (such as an area to the side that will be replaced in post-production by a matte painting). Light, shadows, hours of daylight, and light direction will also need to be considered and noted. Since a location scout may take place months before filming in that area, it is important to consider the expected weather and hours of daylight in the future. If the locations are locked early, some of the features or layout may be incorporated into the storyboards or previs. Some photos of the locations may be used for creating mock-ups or as lighting and rendering environments for CG models.

Tech Scout

Once the basic locations are decided on, the production department usually schedules a tech scout or multiple tech scouts. The primary purpose of a tech scout is to allow each department to see the locations and sets directly and review them for technical issues. The director, producer, and production designer usually take the key department heads to check out the approved locations and sets in progress. This includes the VFX Supervisor and VFX Producer or other support persons. Typically, a handout of drawings, layouts with basic measurements, and concept artwork is provided.

At each location the director describes the sequence that will take place and specifics about how he or she wants to use the location. The production designer describes what changes or additions will be done. They may be modifying the location or constructing a set on the location. In some cases the production designer may have artwork or a design miniature to help explain the layout. Storyboards and previs may be shown on the location. Armed with this information, the group then discusses any issues regarding the location. Any problems for a department are flagged and an attempt is made to solve potential problems.

From a visual effects standpoint, the VFX Supervisor has to see how the location or set will work for the visual effects shots. The same issues covered by the location scout will need to be reviewed, with more details. How different are the locations and sets compared to the storyboards or previs? Will this require a revised budget or a rethinking of the techniques? Are there items at the location that can or should be used for interactivity? The VFX Supervisor needs to visualize the shots currently designed for this location or set and determine what post work will be required to complete the intended scene.

Production Meeting

Many meetings are held throughout the pre-production phase, but at some point close to shooting, a full production meeting is held. All department heads attend, along with the director and producer. This is meant to provide the big picture to all departments and to cover enough details so that surprises on the day of the shoot are minimized. The storyboards are usually displayed around the room and passed out to each person as a book. If previs exists for a sequence, it will be presented on a large screen if possible. The 1st AD usually runs the meeting and steps through the sequences. For complex sequences each shot may be quickly stepped through, with a representative from each key department discussing what they will be doing for the shot (i.e., stunts will be handling the driving car, special effects will be knocking over the hydrant, and visual effects will add the rainbow in post).

Various department heads raise any special requirements. Visual effects will need to discuss the unique requirements they have, along with a quick rundown of the process.

Visual effects should flag any new issues raised in the meeting that would affect or alter the visual effects.

DESIGNING VISUAL EFFECTS SHOTS

Scott Squires

One of the key elements to a successful visual effects shot is the design. With today’s technology most of the technical issues can be resolved (even if problematic), but there is little point in doing an elaborate and costly visual effects shot if the design is unsuccessful. Some suggested guidelines follow, but as with any art form, there are no absolute rules.

Visual effects shots require the same eye for composition as standard live-action shots, but there are a number of issues that directly relate to visual effects shots.

The costs and planning required for visual effects may lead the director to avoid dealing with the visual effects and the VFX Supervisor. This approach tends to lead to a more painful process during production and post-production. It also increases the costs and, more importantly, decreases the quality of the final shots if the visual effects team is second-guessing the director. The VFX Supervisor should be looked at as a creative collaborator and be relied on along with the director of photography and production designer to help design the film. The VFX Supervisor is there to serve the director and the film to create the appropriate effects in the most efficient way possible.

The main objective of any shot is to help communicate the story the filmmaker is trying to tell. It is easy to lose sight of this and have a visual effects shot become just eye candy with no intrinsic storytelling value. Visual effects are tools for the filmmaker that open up an almost unlimited range of stories that can be told on film. Locations, time periods, sets, props, and even the characters can all be changed or rendered from scratch. It is very easy to abuse such powerful tools and get caught up in the technique and pure visuals created. When anything becomes possible, including during post-production, there may not be as much care and design as there should be in pre-production. When an audience complains about too much CGI, this usually means there are too many unnecessary shots or that the shots have been pushed beyond the level expected for the type of movie.

Guidelines for Directors

1.  Work with the VFX Supervisor and his or her team. Don’t make the mistake of thinking that they just bring technical knowledge to your project. They bring a creative eye and experience that can help design the best visual effects for your project.

2.  Assume everything is real and exists on the set. How would this scene be shot if everything were really on the set or location? This mind-set avoids treating visual effects shots differently.

3.  Design for the finished shots. The VFX Supervisor will have to work out the techniques required and determine the different pieces to be shot.

4.  Do the first pass of the storyboards without limitations. What visuals are needed? These may need to be pared back as the storyboards are reviewed, but sometimes shots are neutered to try to make a budget based on incorrect assumptions about the costs for the visual effects or what the technical requirements may be.

5.  Design the shots necessary to tell the story well. If a particular story point can be made in two simple shots, then it may not be necessary to turn it into a 30-shot extravaganza. This is something to consider in the large scope of the film. Use the visual effects shot budget where it counts.

Storyboards

On a traditional live-action film, the director is unlikely to have storyboards. The director creates a shot list and then works with the director of photography and the camera operator to determine how best to visually capture the action that has been blocked out with the actors. Some directors are focused entirely on the actors and allow the director of photography to lay out the visuals. If storyboards are done for a live-action film, they are typically used as a rough starting point to be revised on the set with the director of photography.

Storyboards for visual effects are used to make budgets and to plan the multiple elements that need to be shot or created. They are usually critical for determining the visual effects techniques and assets required. There is still some flexibility when shooting, but it will be dependent on the specific shot.

A director typically works closely with a storyboard artist. Directors have varying degrees of visual design sense. If the director doesn’t have much of a visual sense, then the first pass at shot design falls into the hands of the storyboard artist.

Because some directors want to shoot without planning, they avoid storyboards or simply do a pass to appease the studio and then ignore them in production. This approach has multiple problems. The budget may not take into account what the director really wants. It may be necessary to tell a director on the set that it’s not possible to do what is now being asked. The stunt team and special effects crew may have to build special rigs and set them up for the shot being described. Additional plates for the scene may have already been shot for different camera setups.

This isn’t much different from a director walking on set and wanting to shoot in a direction where there is no set. When the physical limits are obvious, concessions are more likely to be made. Since the visual effects costs and limits aren’t quite as obvious, there’s a danger that shots will be done anyway with the intention of working it out later. When “later” means in post-production, it’s likely there will have to be even larger compromises to the shots, and it becomes a difficult situation for the supervisors caught between the director and studio. With proper planning and storyboards, the odds of success are much higher, the final shot quality will likely be better, and the shooting time will probably be less. All of this is very dependent on the director and the specifics of the shot.

Previs

The next step up from storyboards is previs. Details of previs are covered in the main previs section later in this chapter. The moving imagery in the previs provides directors with an even more precise method to convey their vision. This allows design of not only the basic composition but the timing and camera motion as well. By editing the previs together, it’s possible to create a sense of the design for the whole sequence. Storyboards and previs will then be used on the set to help maintain the design and consistencies of the shots.

Objective of the Shot

If the primary design goal of the shot is to make it cool and awesome rather than to advance the story, then it will likely fail. The reality these days is that it’s very difficult, if not impossible, to wow the audience. There was a time at the start of digital visual effects when it was possible to show something totally new and different by technique alone. With the sheer volume of moving images these days, however, it’s hard to amaze the audience even with something original. The best solution to creating compelling images is to design shots that enhance the story and then have the director work with the production designer, director of photography, and VFX Supervisor to come up with the best possible visuals for the film.

Even with the best intentions, the original concept of a shot may veer off course. The original storyboard is sketched up with the director and a storyboard artist. This is then reinterpreted by a previs artist, and then reinterpreted by a DP. Finally, in post, the animator, technical director, lighting artist, and compositor working on the shot may enhance it. In many cases this collaboration improves the shot, but there are times when the changes are at cross-purposes with the original intent of the shot.

Concept Art

It helps, of course, to have finished concept art when doing the storyboards and designing the shots. The design of the creature or scenes being painting as concept art can then be included in the storyboards and more accurately represent the final shots. Ideally, concept art is done in the same aspect ratio as the film and represents a frame in the sequence. As the concept art, storyboards, and previs progress, they sometimes inspire the director and writer to incorporate ideas from the various artists into the story and script.

Continuity

One of the largest issues with visual effects occurs when the visual effects shots are treated and designed differently from their surrounding shots. Sometimes the director and storyboard artist design the shots differently by making them simple and typical. An example might be when a sequence starts with a number of handheld shots for the live action, followed by a locked-off shot of a building matte painting, and then back to handheld shots. The inverse is also true (the visual effects camera turns into a supercrane that does impossible moves). The film should flow smoothly and the visual effects shots should integrate with the surrounding live-action shots without calling attention to themselves.

Photorealism

Directors are keen on photorealism but this, of course, is very dependent on the subject matter. A scene may include objects or images that have no foundation in reality. In these cases not only does the execution have to be great, but the narrative of the film also has to convince the audience to suspend their disbelief. If photorealism is the aim, then anything that breaks that goal will break the shot. Non-photoreal camera moves and exaggerated color timing are two things that can easily change the shot from being photoreal to being very stylized. Stylized imagery can pull the audience out of the shot (depending on the style and the film) and lose any sense of photorealism, which is a creative call. Photoreal and stylized images usually work at cross-purposes.

If a shot ignores standard physics, such as a CG jet that does an impossible maneuver, the realism of the shot may be ruined. As with other aspects of filmmaking, the director and VFX Supervisor will have to work out the balance of realism versus cinematic impact. These are the same issues the production designer and the director of photography have to deal with.

Original Concepts

At times the director will request something totally different, and the VFX Supervisor may be able to suggest certain new techniques or creative approaches. Tests should be scheduled and budgeted to explore new concepts. Some alternating of concept art and tests might happen as the ideas and results are refined. Sometimes the request to have something unique may actually mean to have an interesting shot, just like one already featured in another film. It is best to get this clarified before a lot of time and effort are put into developing something that is not actually original.

Budget

A script might have a simple shot description: Only a wood fence separates the hero from the monster. The VFX Supervisor envisions a shot with a solid fence and the hero below the line of the fence so that a simple matte can be created. The director may be envisioning five shots of a dilapidated fence with vines that the camera swoops up and over to a reverse of an over-the-shoulder from the monster. This is where storyboards and previs help clarify the director’s vision. This will provide a much more accurate budget as well as help determine the best techniques available.

By reflex many supervisors may try to steer the shots to something simple and less expensive (based on studio pressure and past projects). Care should be taken to avoid sacrificing the film design and making adjustments too early.

Reality and Magic

Sometimes a secondary purpose of a shot is to sell the audience on its reality. Care has to be taken that this is subtle. For example, in Forrest Gump (1994), one of the characters has lost his legs. This is treated in a realistic manner, and since the audience knows that this can happen in real life, they tend to accept it in context and not focus on the visual effects. There is no need to “sell” the visual effect. Later, there is a shot where the character swings his partial legs in a way his real legs would not be able to move. This is a subtle hint to the audience to keep believing.

Some other directors may have approached this in a different way, with the intention of showing the audience that it’s all real in much the same way a magician does. Focusing on the visual effect and trying hard to prove it’s real has the unfortunate consequence of causing the audience to look at the shot as a visual effects shot and not an emotional shot helping to tell the story. A magician wants to point out his accomplishment to the audience, but a visual effects artist wants the shot to work in context.

Camera Angles

Most film shots are done from the approximate height of a person. To create the sense of an object of great height, the camera can be lower and tilted up. This is very useful for something like a giant. Looking down typically gives the sense of smaller objects. This is one of the reasons why, when shooting physical miniatures, the camera is kept at the model’s eye level (6 feet scaled to model scale) when possible. When the camera looks down on a model, this tends to emphasize the model aspect. If the camera is to move over the model, mimicking an aerial shot in real life, it is best to replicate the motion and speed of a scaled helicopter. If the camera moves too quickly or in a manner not possible in real life at that scale, the illusion will be broken and the miniatures will look like what they are—miniatures.

For initial storyboards the director may select pure profiles or straight-on designs to get their ideas across. When it comes to actual shooting, though, it is usually better to shoot a bit off axis, such as at a ¾ angle, to provide more of a sense of depth and dynamics. This will also make the pure profile or straight-on shots stand out for more impact.

Framing

In addition to standard composition guidelines (such as designing the shot so it leads the eye to specific areas), the framing should be considered for its clarity and impact. Is this the best angle to make the story point the shot is trying to tell? If the framing is too tight or the angle is too abstract, the audience may be confused or may miss the point of the shot.

Scale

Visual effects are frequently called on to create creatures or objects that don’t exist in real life. One of the issues that needs to be solved in such a case is to indicate to the audience the scale of these types of items. Sensing the scale of a smooth metallic cube in space is very difficult. It could be 1 inch or 1000 miles across. Everyone working on the film knows the scale it’s supposed to be, so it is easy to forget to convey even this type of basic information to the audience in a visual form.

The best way to indicate scale is to show a comparison to a known object that overlaps it. If two fingers reach into the frame and grab the cube, then instantly the audience knows its scale. If the cube is behind the earth, then its scale is now known to be gigantic. In the example of the cube, it would also be possible to attach a ladder or door or some known frame of reference to the model to indicate scale.

Detail

Most man-made objects will be judged based on their complexity. A smooth object will be considered to be small, and an object with a lot of detail will typically be assumed to be large unless otherwise indicated. Physical model spaceships may be covered with detailed items such as parts from commercial models. Smooth-sided physical spaceships may be dabbed in cosmic crud—an affectionate term for a mix of modeling paste that provides a sense of organic texture. These same approaches can be used on CG models. If a CG model lacks detail, it looks either very small or, more likely, fake. Lack of detail and varied texture in CG models is what usually gives them away. Note that in nature even microscopic objects can be very complex.

Speed

The speed at which an object moves also tends to convey its sense of size. The faster it moves, the smaller it will seem to be, especially if it shows no sense of momentum and weight. This becomes problematic when the director wants a very large creature or character to move very fast and to change direction on a dime. Since the scale is likely to have been established, the creature just looks artificially lightweight, and this in turn makes the creature less real and does the opposite of what the director actually wanted to achieve.

Scaled Images

Creating large or small versions of people and props is fairly common. Shooting full-size objects (person, animal, etc.) and merely rescaling them in the compositing software is fairly straightforward. The problem is that they tend to look exactly like what they are. Just as fire and water are tough to scale realistically, so are many images. When possible, adjust the object as much as feasible to help sell the scale. This may include things such as clothing made out of thicker cloth that will look natural when scaled smaller in the composite. In this example, since thread and cloth thickness are a known size, if they are compensated for in the original costume, they will look correct when scaled in the shots.

Depth of Field

Depth of field can be useful when trying to keep the audience focused on a character or object. Anything in front of or behind the depth of field will be out of focus and blurred. This is one of the many optical effects from standard photography that can help create a convincing shot. When shooting scaled images (such as a person who’s supposed to be 3 inches tall), re-creating the shallow depth of field that is common for macro photography will help this match the audience’s expectations. When shooting a miniature you want to have as much depth of field as possible to replicate a full size set or object. Virtual shots and animated features tend to simply set the depth of field to whatever is desired without considering the focal length or lighting. A sunny outdoor scene shot with a wide-angle lens would look odd with a shallow depth of field. These are the types of things that people subconsciously notice as being a bit off. Try to base the design on what would be reasonable if the object were really being filmed.

Sequence of Shots

Shots need to be designed with the sequence and surrounding shots in mind. If each shot is designed independently, then each may be great individually, but when viewed as a sequence, redundancies and missed opportunities may arise. Shots should flow from one to another and be used to build an emotional impact.

Camera Motion

Visual effects allows a camera to perform unlimited moves between scenes or within a virtual scene. This can be used to create very stylized scenes, but as previously noted, this can cause problems if the intent is to be as photoreal as possible. Sometimes if the actor is doing a complex action, it’s best to keep the camera motion subdued so that the audience can view the action clearly. A complex and quick camera on top of action in the scene can be confusing to the audience and lose the point of the shot. The balance is trying to create a visceral experience that maintains the story points.

Less Is More

Sometimes the most powerful shots are the simplest ones. In many cases there is a desire to increase the number of extras, space ships, creatures, etc., within a scene or to keep layering element after element in an attempt to “amp up” the action. An example is a fight between two characters. If the audience knows the two characters, then it can become both an emotional and an action scene. If the same shot were done with thousands of people, then the end result is likely to be a dilution of interest instead of the desired increase in impact. The same thing applies to the number of spaceships in a scene. Layering a number of fighting creatures, thrown objects, smoke, and dust may result in a muddle instead of a dramatic scene.

With visual effects there can be a tendency to overdesign a shot and try to include everything including the kitchen sink. Spending a lot of time and money on a shot that becomes a 2-second quick cut or is so full of things that the audience has no idea what they are looking at is a waste.

Action Pacing

If an action scene goes on too long, especially with “in your face” visual effects, the audience is likely to get bored. It is important for the action to vary much as a roller coaster has a rise and fall of action. The impact of a shot has much to do with the surrounding shots. A steady stream of action doesn’t provide a relative difference for the audience and doesn’t allow for any suspense or anticipation.

CG Characters

It takes a great script, direction, and animation to make the audience care about a CG character. This is especially true in a visual effects film where the CG character exists in a real world. If the CG character defies natural physics and anything is possible, then it can easily turn into a cartoon where any violence doesn’t mean anything.

Creatures and Character Design

The design of creatures and characters can play a major role in the film. It will have an impact on the creative success and the technical approaches used. Much effort should be spent testing and refining the designs.

In District 9 (2009), the aliens worked very well for the visuals and yet had some design aspects that aided the technical approach. By keeping the aliens close to human size, actors could be used to stand in for the aliens and compositions with humans and aliens could easily work. The hard shells reduced the costs and difficulties of dealing with flexible skin, hair, and feathers. The alien language eliminated the need for precise lip syncing.

Avatar (2009) used character design to its advantage. The humanoid characters were similar enough to humans to allow the audience to connect and made it easier to utilize motion capture of actors. The differences (blue skin, facial structure, etc.) avoided the issue of the “uncanny valley.” The uncanny valley refers to the result that occurs when an attempt is made to mimic humans in look and action but the closer it gets to matching a human, the more creepy it can be for the audience if it does not succeed exactly. This has been an issue with some motion capture animated films.

Powers of 10 Shots

It’s not unusual for a director to want a powers of 10 shot. The camera starts at a vast distance, usually in space, and then moves down to finally end up at the reflection in a person’s eye, or the reverse. These shots have been done [Contact (1997), The ’Burbs (1989), etc.], so they are not as original as they might appear. They also tend to be difficult, expensive, and questionable as to how much impact they have on an audience who has already seen these types of shots in other films and commercials.

Oner

Oner is the term for doing one long shot instead of breaking it into multiple shots with different angles or cutaways. This may serve the narrative well but at other times it’s devised to prove the shot is real (not cheating by cutting away) or to try to reduce costs. Since visual effects are budgeted per shot, some thought can be given to combining multiple shots into one to reduce the budget. However, any long and complex shot is likely to cost more time and money than if it were split up. Depending on the scene, cutaways can show the details and reactions, which may help create more of an emotional impact than holding on a single shot for an extended length of time.

Summary

When designing shots and sequences, it is worth coming at it from the viewpoint of an artist. Any reference material of great art, photos, and scenes from other films can be viewed as inspiration. If photorealism is key, then reference documentary photos and films. Base all aspects of the shot on as much reality as possible. If a stylized look is desired, then it may be necessary to take it to a level such that it doesn’t appear to be poorly done photoreal images. Take advantage of all the parameters that visual effects provide—the lighting, color, composition, camera motion, and object motion—as long as it works with the surrounding live action and helps to tell the story.

VISUAL EFFECTS TECHNIQUES

Scott Squires

Many factors can influence the exact technique used for a visual effects shot or sequence. In most cases it is not a matter of figuring out how to do a visual effect but of determining which technique will work best for this particular project. Each chosen technique will have some type of trade-off between cost, time, quality, and flexibility. Some of the main issues to consider are discussed next.

Technique Considerations

Budget

This is one of the largest issues to consider when selecting techniques. There is never enough money in the budget. On low-budget productions it may be necessary to select less expensive techniques by rethinking the problem and reviewing all options. It is usually best to consider reducing the number of shots and the complexity of shots to a minimum to tell the story but still keep within the budget. It is better to have 100 well-done shots rather than 200 poorly done shots. This will require working closely with the director and editor to make clever design decisions that make the most of the budget. Lower budget productions also have to be even more careful about time and changes.

Time

The supervisor has to make it clear that enough time has to be allocated in all stages of production (including pre-production). Too little time will result in much higher budgets and, more importantly, reduce the quality of work. Visual effects shots can usually be roughed in fairly quickly, but raising them to the level where they hold up on the big screen takes time. To make them great takes even longer.

Number of Shots

A large number of similar shots can support more R&D and assets than a single shot. A large number of shots will make an automated solution more useful. With a single one-off shot, it would be overkill to spend months developing a special computer script. If there are a number of similar shots, then the learning curve on the first shots likely will make the later shots more efficient.

Length of Shots

A 1-second shot is easier to create as a quick illusion, even if hand done, than a 30-second shot. The longer shots will require even more care in selecting a technique.

Complexity

A large number of running creatures moving through an elaborate environment will certainly require more techniques (collision avoidance, crowd animation, etc.) than a simple object moving through a scene.

Flexibility and Time on a Live-Action Set

Some techniques take more time or special rigging on set to accomplish (motion control, multiple elements, etc.). If circumstances change or for some reason the technique is not possible to schedule, then a different technique will have to be considered.

Flexibility in Post

Some techniques allow more flexibility in post-production, which can be necessary for films that are in flux or when a director and studio want to make a number of adjustments after the edit. Examples would be the choice between a CG building (which can be changed or rendered late in post-production) and a physical miniature building (which is what it is when filmed). Shooting separate elements also allows more flexibility in postproduction.

Camera Motion

A locked-off camera is simpler to work with than a large crane or a handheld camera. A moving camera may dictate special techniques (such as matchmoving) that a locked-off shot would not.

Look

Most productions request images that are photoreal, but even in these cases the realism will be adjusted to make the images cinematic. Those involved want the sense of realism but not necessarily realism (the same applies to photographic lighting). Some productions will require very stylized imagery, which will require approaches different from a photoreal approach in both original photography and post-production.

Additional Suggestions for Determining Techniques

The Actual Shot Requirements

Communicate with the director to find out specifically what he or she requires. Also be sure to consult with other departments to see how they can help with a solution. A communication error can have the visual effects crew trying to accomplish a different shot from what is actually requested. Note that this can change at any point and needs to be confirmed before starting the shot(s).

Breaking It Down to the Simplest Requirements

Do not become overwhelmed by the complexity and number of shots. If there’s a choice between a complex and a simple solution, the simple solution is usually the better option if everything else is equal.

Review Other Films and Alternative Techniques

Review other films that have achieved anything similar. Do research on how they were done. Use the Internet, SIGGRAPH¹¹ notes, behind-the-scene supplements on DVDs, Cinefex,¹² and other sources of information.

Think Outside the Box

Consider other techniques: practical special effects, reverse action, shooting upside down, in-camera effects, or approaches a stage magician might take.

Think Pre-Digital

Not every visual effects shot needs to be done using digital techniques. The trailer for Close Encounters of the Third Kind (1977) had the camera moving down a road at night with a glow beyond the mountains. This was a motion control shot done in smoke. The road was 2 feet across, with forced perspective. The mountains were 3-foot-tall cardboard. Someone lay behind the “mountains” and adjusted the brightness of the glow by slowly turning a dimmer up and down. This same shot in CG could be turned into a very elaborate and complex shot. There are many examples of this from the pre-digital era.

Budget Time and Money for Testing

This is especially true for new techniques and for major sequences. Budget both photography and post-production work on test shots.

Research and Development

Experimenting with software and other digital techniques will be required. Explore the options or develop new ones.

Keep the End Result in Sight

It is easy to get sidetracked on solving the problem while losing sight of what the final results need to be. Remember: All that matters is the final results.

Hand Versus Automated Work

Sometimes doing something by hand or even frame by frame is a faster, cheaper, and easier solution. An example would be spending a week on a complex green screen with problems that could have been solved with a rotoscope and standard composite in a couple of days. The same thing applies to computer scripts and simulations. Painting out a rendering error on a couple of frames is faster than rerendering the shot.

Try Not to Solve Every Permutation

Software engineers and visual effects artists sometimes try to cover every possible variation on a problem. Just solve what needs to be solved.

Balance Techniques

Try to use the same technique for a number of shots. This will tend to make it faster and easier since the crew will get up to speed and be able to apply what they have learned to new shots. However, there are times when a shot may be unique and require a different approach from the rest of the sequence. Balance the best technique for each shot with the efficiencies of sequence techniques.

Cheating

If the same effect can be achieved in front of the camera by any other means, do it. Theatrical movies are created from illusions. The front of a house may only be a facade and contain no actual rooms or even sides. The marble floors you see are likely the work of a gifted painter using a sponge to paint pieces of Masonite. If you can do something simple that provides the effect, then it probably doesn’t matter that it is technically incorrect.

One on-set example of this was a shot for The Mask (1994). In the wide shot large items were going to be pulled out of Jim Carrey’s pants pockets, so computer graphics pants were planned to show the objects stretching the pants. On the day of the shoot, the director wanted the shot tighter and Carrey was wearing baggy pants. The pants were turned into shorts with scissors and holes were made in the pockets that allowed props to be pushed up by assistants. This saved the cost of a visual effects shot and allowed them to do it live.

Examples

Here are a few examples of trade-offs to be made when determining the techniques to use:

•   Create a castle on a hill where none exists. One shot. Add flags and people to add life to it. Matte painting will likely be the simplest and most cost-effective approach. Part of the painting could be based on photos of real castles. Painting would allow the image to exactly match the lighting and the angle required.

   Flags on the castle could be done by shooting real flags against a green screen. If these are small in the frame they could be shot on 24p¹³ standard or HD consumer video. People could be shot on a green screen from the correct perspective using a similar type of video if they are small enough in frame. Both the flags and the people could be done with computer graphics, but for most companies, simulating them, preparing the models, and making them look real would likely take more time and effort than filming them.

   Closer coverage could be done with the actors in front of a castle set piece consisting of a section of one or two walls. These would be fully live-action shots and require no visual effects.

•   Same shot but with a simple camera move. If the castle is far enough away and the camera move is small, then a matte painting could still be used since the perspective change would not be enough to show a problem. 2D¹⁴ tracking software could be used.

   If the camera move is large enough that a perspective change is visible, then this could be done as a 2.5D¹⁵ matte painting solution. In a 3D program the matte painting is projected onto a simple 3D model. 3D tracking would be done to match the camera motion. The simple model would provide enough sense of perspective change without requiring a fully detailed 3D model.

•   Static camera but multiple shots. If the shots are all from the same camera setup, then a single matte painting could be used, with minor changes for lighting as necessary. If many different views are required, then it may be more cost effective to do it as a model (CG or physical) than to create a matte painting for each shot.

•   Complex camera move, such as flying from the ground and over the castle. Note that the camera move should mimic a real camera move (such as a helicopter) in terms of speed and motion unless the desire is for it to be stylized. This would be done as a physical or computer graphic model of the castle.

In this case it may be worth doing the flags and people as computer graphics so the perspective would be easier to match.

There are trade-offs to both of these:

Computer Graphics Advantages:

•   If the castle or part of the castle needs to transform.

•   If a CG character or creature is interacting with the castle.

•   Easier to re-do the shot later if there was a change. With a physical model once the model was shot it would require a full reshoot if there was a major model change or different view required.

•   Unlimited number of takes and lighting variations.

•   Unlimited number of dynamic simulations for breaking or falling. Downside can be hard to control.

•   If the visual effects company is already doing 3D visual effects and doesn’t want to subcontract the model construction and photography.

Physical Model Advantages:

•   Relatively easy to do organic shapes including things like flowering vines on buildings.

•   Real interaction. Breaking models can be built to break at specific points and to crush based on a design.

•   Being physical makes it more tangible to work with in terms of shot angles.

Here are a few techniques to composite a person in front of a background:

1. Blue or green screen. Some video formats work better with green screens due to color response, but most of the time the choice of screen color is dictated by the dominant color of the costumes. Blue costumes would require a green screen.

   Fine detail such as hair, glass, water, and shadows can be extracted. These may require extra work such as creating garbage mattes and specific key settings.

2. Rotoscoping. If it is not possible to shoot with a colored screen or if a decision is made later to use just the foreground, then rotoscoping the foreground image is typically a reasonable way to create a matte.

   If the live action shot against a colored screen has too many problems (a lot of contamination, very unevenly lit, etc.), then rotoscoping may be faster and better than just a straight key.

   If the main issue is to put something in the middle ground (e.g., a creature or object between the actor and the background), then rotoscoping is usually preferred. This allows the subject and the background to be shot at the same time and with the same lighting and camera move. This could be done as a blue or green screen, but that would require shooting the actor in front of the screen, removing the screen, and then shooting just the background. This would take more time on location or the set.

Summary

Don’t rush to assign the first technique that seems to apply. Give some thought to the implications and the trade-offs of various approaches. Expand your knowledge and thinking so you have more options from which to select. Keep in mind the final results as your target. Keep the technique as simple as possible for the desired effect. The technique chosen will have a large impact on the final results and difficulty getting there.

WHAT IS PREVIS?

Mat Beck¹⁶

Previs, which is an abbreviation of previsualization, has been around since the first director framed a shot with his thumbs and forefingers and the first pencil sketch illustrated a proposed set. It is a natural function of the need to figure out the visual story to be told and how best to tell it. Previs can be simply described as a visual rough draft of a shot, sequence, or show. But that would underestimate its power. It often represents not only the best way to develop a sequence but the best way to collaboratively link the variety of departments, technologies, and points of view that have to come together in a modern production to bring the sequence to life.

As the technology and scope of previs have grown, it has become more challenging to precisely define exactly what qualifies as previs and what does not. A previs sequence can be composed of anything from animated storyboards to video shot with stand-ins to CG motion-captured characters rendered in a realtime virtual environment. Regardless of technique or practitioner, it seems that any definition would include certain key concepts:

•   Previs is visual. It is a collection of images (generally moving) that can be viewed, manipulated, and discussed.

•   Previs comes before a larger and more complex production effort, thereby conserving resources. Even postvis (discussed later), which comes after main production, still comes before the significant effort of more complex visual effects work.

•   Because the techniques are more economical and have quick turnaround, they can be used for experimentation and exploration of images, ideas, etc.

•   It is a tool for communication and collaboration. The images promote a common understanding of what is intended.

•   It provides guidance for the larger effort down the road.

Here are the definitions proposed by the Joint Technology Subcommittee on Previsualization, a collaboration between the Visual Effects Society (VES), the Art Director’s Guild (ADG), and the American Society of Cinematographers (ASC)¹⁷:

Previs is a collaborative process that generates preliminary versions of shots or sequences, predominantly using 3D animation tools and a virtual environment. It enables filmmakers to visually explore creative ideas, plan technical solutions, and communicate a shared vision for efficient production.

The reference to filmmakers includes anyone performing visual storytelling for movies, television, games, and other related media.

The same committee recognized a number of subgenres of previs in current practice:

•   Pitchvis illustrates the potential of a project before it has been fully funded or greenlit. As part of development, these sequences are conceptual, to be refined or replaced during pre-production. (Although pitchvis is not part of the main production process, it allows people like executives and investors to take a first look at the potential result.)

•   Technical previs incorporates and generates accurate camera, lighting, design, and scene layout information to help define production requirements. This often takes the form of dimensional diagrams that illustrate how particular shots can be accomplished, using real-world terms and measurements. (In good practice, even preliminary previs is most often based on accurate real-world data, allowing technical data to be more easily derived.)

•   On-set previs creates real-time (or near-real-time) visualizations on location to help the director, VFX Supervisor, and crew quickly evaluate captured imagery. This includes the use of techniques that can synchronize and composite live photography with 2D or 3D virtual elements for immediate visual feedback.

•   Postvis combines digital elements and production photography to validate footage selection, provide placeholder shots for editorial, and refine effects designs. Edits incorporating postvis sequences are often shown to test audiences for feedback and to producers and visual effects vendors for planning and budgeting.

•   D-vis (design visualization) utilizes a virtual framework in preproduction that allows for early in-depth design collaboration between the filmmakers. Before shots are developed, d-vis provides a preliminary, accurate virtual design space within which production requirements can be tested, and locations can be scouted. Approved design assets are created and made available to other previs processes.

In recent years, digital previs (in virtual 3D space) is playing a more and more dominant role. It offers a path to new forms of filmmaking (see later section on advanced techniques). But traditional practical previs techniques also continue to provide economical ways to communicate desired action and imagery. Regardless of the technique chosen, the principal goal has always remained the same. By developing and then expressing the intention of a sequence in an accessible visual format, successful previs increases the likelihood that that intention will eventually be realized.

DEVELOPMENT OF PREVIS TECHNIQUES

Mat Beck, Stephanie Argy

History and Background

Over the years, movies have been previsualized using a variety of techniques, including storyboards, story reels, live-action tests, photography using foam-core or dime store models, “proof-of-concept” work, and editorial precomposites—all of which relate to visual effects and the broader concept of visualizing a film.

There is no requirement that storyboards or previs be used in pre-production. Although prominent directors like Alfred Hitchcock and Orson Welles were renowned for meticulously planning out their films ahead of time, other filmmakers have relied more on improvisation, but storyboards and previs have become standard tools for clarifying difficult issues in advance.

In animation, story reels were a filmed assembly of storyboards (or other key frames), put together to give an early feel for the look and pacing of the final film. This has been a key production step at Disney since their earliest feature films.

Some illustrators became specialists at rendering detailed “exploded” images to deconstruct complex visual effects sequences—which were similar to the images now generated in technical previsualization using digital tools. Other art department staff became expert at projecting lens angle information and determining how much practical set would need to be constructed for anticipated camera views—and where matte paintings might be required.

Editors and VFX Designers have used (and continue to use) preexisting footage to help refine visual effects while they are still in the planning phase. Such “rip-o-matics” are another method of previsualization, which can be cut together well in advance of principal photography. The most famous example of this may be George Lucas’ use of World War II fighter plane footage for Star Wars (1977), which enabled him to plan out his space battles.

Later, for Return of the Jedi (1983), Lucas used toy figures shot with a lipstick video camera to plan out the sequence in which speeder bikes race through a forest.

In the 1980s, computer-generated imagery first began to be used for previs. For 1982’s Tron, Bill Kroyer and Jerry Reese used a combination of drawn storyboards and vector-line CG graphics for crucial scenes such as the lightcycle chase and the solar sailor.

Another of the earliest instances was in the film The Boy Who Could Fly (1986). To figure out how to stage an elaborate sequence in which two children fly over a school carnival, production designer Jim Bissell turned to the computer graphics company Omnibus, which created a virtual representation of the scene that enabled Bissell to see where he could place towers to support the actors on wires, as well as the Skycam that would cover their flight. James Cameron also used video cameras and miniatures to plan out sequences for the Abyss (1989).

Two groups made a significant contribution to the development of digital previs: On the East Coast, in the early to mid-1990s, Douglas Trumbull hired students from the Harvard Graduate School of Design, Yale, and the Massachusetts Institute of Technology to work at his company, Ride Film, doing what he called image engineering. Using CAD systems, the group began by working on a project called Luxor Live (1996) and then went on to do the movie Judge Dredd (1995).

Meanwhile, on the West Coast, Industrial Light and Magic formed a previs division called JAK Films, which created its first full sequences for the movie Mission: Impossible (1996). The group then went on to work on all three Star Wars prequels: The Phantom Menace (1999), Attack of the Clones (2002), and Revenge of the Sith (2005).

As previs evolved, it became clear that it could be used to provide some very useful technical information to the production crew. On Starship Troopers (1997), for example, the motion control rigs (crane, track, etc.) were modeled along with spaceships in virtual space so that not only spaceship animations but model and camera data could be handed off to the motion control unit for subsequent shooting. Information generated this way reportedly increased throughput by more than 10 times.

Other studios and film projects applied virtual previs in ways suited to the specialized needs of their projects. Disney built on its tradition of previsualizing animations, using digital tools to figure out how to combine computer-generated characters with live-action plates in the movie Dinosaur (2000). In the Fox animated film Titan AE (2000), previs elements became the basis for final shots. And Panic Room (2002) offered one of the first uses of previs for straight-up filmmaking, as opposed to visual effects, allowing David Fincher to use virtual cranes, the camera, and the environment to take best advantage of the movie’s elaborate set.

In current practice, previs most commonly takes the form of 3D animation within a virtual environment, but traditional techniques remain an efficient and economical tool. Storyboards and live-action footage may be incorporated with CG elements. As in all visual effects work, previs can be a hybrid composite technique, taking advantage of whatever works to refine, convey, and implement an idea.

THE APPLICATIONS OF PREVIS: WHO BENEFITS FROM IT AND HOW?

Mat Beck

At its best, previs allows the making of the show before production begins—it is a form of rehearsal for an entire production. Every department can benefit, both in its internal operation and in its myriad communications with the other departments. Not every previs will be suitable for every application in scope or level of detail, but the arena of possible influence is broad—assuming, of course, that the work of the previs is carried forward into the later stages of production.

The following is a list of possible benefits/applications for the previs process, organized by department.

Writers can use previs to:

•   Work out story concepts as part of development. Seeing a story even roughly put together on screen can be as beneficial as a script read-through to experience written words coming to life.

Directors can use previs to:

•   Engage in blue-sky concept building initially unencumbered by implementation considerations. Before previs has to settle down and be responsible to the realities of production, it can sow its wild oats in the space of whatever is imaginable.

•   Build compelling sequences through experimentation at a low burn rate (lower rate of expenditure).

•   Limit excessive coverage by predetermining what angles are necessary and which are not (see the section titled Camera and Art Departments: A Special Case below for savings resulting from shooting and building only what is necessary).

•   Take storyboards to the next level, by making them move.

•   Bypass storyboarding entirely in some cases by building the world of the story and finding the best shots with a virtual camera within that world [sequences from the movie 2012 (2009) provide a recent example].

•   Bypassing conventional production entirely and making the movie in a virtual studio (by using previs techniques with motion capture in a virtual space with virtual cameras, a process available to more advanced practitioners; see more about this in the section titled The Future of Previs: Advanced Techniques below). In those cases, ironically, simple filming of actors or stand-ins is sometimes used to previs the motion capture sessions—like the old-time Warner Brothers animators acting out scenes before animating them.

Producers can use previs to:

•   Sell the movie. The special subcategory pitchvis allows demonstration pieces of key sequences to convince distributors/investors/studios of the potential of a project. More than one movie has been greenlit based on a previs alone. This is an example of previs that is pre-script, pre-director, pre-anything but a concept.

•   Generate a more accurate estimation of the scope of a job—thereby reducing costs for overbuilding, lighting, shooting, etc.

•   Allow more accurate cost estimation for the individual departments and overall project.

•   Achieve an earlier determination of the division of labor between departments—for example, between practical effects and visual effects, between visual effects and set construction, etc.

•   Often working with a VFX Producer, prepare apples-to-apples bidding packages for visual effects vendors.

•   Control the process by making informed decisions earlier, without engaging the full production.

•   Get every department on the same page—or image sequence, if you will.

Camera and Art Departments: A Special Case

The previs process has a special relationship with the camera and art departments for the obvious reason that it is occupied so intimately with movement of the camera within the set. The creative decisions that are embodied in previs need to heavily involve these two departments, not only for the best input, but so that those decisions have the approval of the individual who is charged with executing them.

The relationship of previs with the art department is especially critical because it has primary responsibility for designing the world of the story. It is critical that the two departments maintain clear and easy communication and share a common data space so that designs from the art department are efficiently used in the previs and results from the previs—that is, camera views, compositions, and changes in set requirements—can be easily communicated to the art department.

The concept of a virtual production space has been proposed by the production designer Alex McDowell. The basic idea is the creation of a common data space that accurately represents the world of the production and that informs the production all the way through post-production and beyond (e.g., game design). The term d-vis (design visualization) has been proposed as the name of the process.

Undoubtedly creative responsibilities will evolve as evolving technology blurs some of the boundaries between traditional creative categories and gives different departments a strong interest in the results of a previs, as well as the ability to generate or change it.

Regardless of any changes that occur, three principles seem likely to prevail:

•   the necessity of a common data format that allows clear communication in both directions between the production designer/art department and the previs process,

•   the necessity of early involvement of people with the greatest creative stake in executing the vision, and

•   the necessity of disseminating the common data to all the sectors of the film production that can make use of it.

Art Department involvement with previs, other examples:

•   2D paintings done on top of still images rendered out of 3D CG previs scenes can convey tone, texture, lighting, set extensions, etc., to set dressing, props, SFX, etc.

•   Dimensionally accurate set information, used to set up technical previs, can then be bounced back to the art department along with approved shots and angles so that they can modify sets based on the new information.

•   The determination of how much to build practically, how much to generate digitally, how much greenscreen work is needed, etc., can be derived from technical previs.

•   Needs of special lighting and camera equipment can have an early influence on set design.

•   Previs can help with location issues, defining requirements in advance. For example, time-of-day analyses can be used to figure sun angles, etc.

Directors of photography can use previs to:

•   Help to drive the process by providing critical input on camera moves, lens choice, and composition.

•   Pre-determine equipment needs (including special rigs) early enough to figure budget implications and build what is deemed necessary.

•   Predetermine the size of a green screen.

•   Design or modify a lighting scheme once lens choices and fields of view are known.

•   Perform a virtual prelight, in more advanced systems, using physically accurate models for individual lighting instruments and other main components of the scene.

•   Get a sense of the rhythm and coverage of a scene, based on a preliminary previs cut put together by the editorial department.

Assistant directors can best use previs to:

•   Plan a schedule based on anticipated coverage.

•   Calculate the number of extras (both real and virtual).

•   Help with planning and the consideration of safety issues by using exploded views of complex scenes.

•   Predetermine equipment needs (including special rigs) early enough to figure out a budget.

Actors can use previs to:

•   Understand the flow of scenes.

•   React more convincingly to a yet-to-be-realized CG monster, tidal wave, etc.

Special effects coordinators and stunt coordinators can use previs to:

•   Coordinate with visual effects for division of labor.

•   Determine the size and scope of an effect.

•   Determine the basic timing requirements for their effects or stunts—and coordinate with visual effects and camera to determine whether to shoot high speed or regular speed.

•   Allow early consideration of rigging and safety issues, including keeping rigging and camera from fouling each other.

Editors can use previs to:

•   Precut a scene so that the process of visual storytelling can take place before production begins.

•   Give the director an opportunity to fine-tune what coverage is needed and what is not.

•   Recut a scene, once production has started, with actual photographed elements incorporated into previs, or possible subsequent postvis (see the section titled Postvis below).

•   Stand in for final visual effects in screenings. (Postvis may also be used for this when applicable.)

Editors can also generate simple postvis internally for coordinating with the visual effects department. Any postvis is a useful tool for validating the choice and length of plates to be used in the final visual effects.

And, of course,

VFX Supervisors—when they are not generating or supervising previs—use it in all the ways listed above, including to:

•   Ensure that the shots conceived and the elements shot are in line with the anticipated visual effects production.

•   Provide a clear and inspirational reference on set. There is a lot of power in everyone viewing the gag before shooting it.

•   Ensure a continuum between an original idea and its final screen realization that is as smooth as possible.

•   Tweak visual effects methods based on actual assets that have become available (working with editorial and postvis).

•   Create or influence suitable previs to nudge the production in a direction that serves the director’s vision in a way that is more feasible within the restrictions of schedule, budget, etc.

VFX Producers—working in concert with VFX Supervisors—use the previs to address many of the same concerns of the supervisor as well as the producers, including to:

•   Provide a basis for dialogue, ensuring that the visual effects department is getting and disseminating all necessary information.

•   As mentioned above with the overall producer, achieve an earlier determination of the division of labor between departments—another example is the boundary between real and digital stuntman in a sequence or shot.

•   Again, in concert with the overall producer, provide clear guidance and uniform bidding packages for visual effcts vendors.

POSTVIS

Karen Goulekas

Postvis, like previs, is used to plan and visualize scenes in a production. However, although previs is most often a full-CG approach to planning scenes before filming begins, postvis visualizes scenes after the film is shot using any combination of live-action plates, miniatures, and CG.

Unlike the previs stage, wherein the director and visual effects team can experiment with an open canvas in terms of camera placement and motion, postvis, for the most part, is constrained by the live-action camera moves shot on set during filming. (Full-CG shots can still be visualized without limitation.) Even though these constraints can be somewhat manipulated and/or overridden with 2D compositing techniques, it is important that the basic shooting style already established for the film be respected and adhered to when making these adjustments.

The use of postvis has become an essential part of films, both small and large, that require visual effects to create the final shots. When dealing with a CG character or effect that is critical to the storytelling, it can be difficult for the director and editor to cut together a sequence of live-action plates without the ability to visualize the cut with its CG components. For example, how large will the CG character or effect be in frame? Where will it be positioned in frame, and how fast will it move? Will the camera angle and motion of the plate allow the CG character or effect to perform the required action? Even scenes featuring live actors shot against a blue or green screen can benefit from postvis as a means of ensuring the match between the actors and the live-action, miniature, or full-CG environment they need to interact with.

Therefore, once the first pass of the edit using the various live-action and miniature plates is available, the postvis can be used to determine whether the various elements and their corresponding CG will work together correctly.

Unlike previs, where the cost of each shot is simply a percentage of the artist and equipment weekly rate, postvis incurs additional hard costs. These costs include, but are not limited to, film scanning (unless the project has been shot digitally), camera tracking, and, for some shots, roto and paint work. Because the edit is only a “best guess,” the postvis work may show that different plates or action is required. This will mean that a new postvis will need to be created using the new material, resulting in added costs.

However, in the long run, this is money well spent because the costs of camera tracking, roto, paint, and possibly complete redos are far less expensive than the money spent with the visual effects vendor moving too far ahead into animation and effects work on a plate before discovering that a different plate needs to be selected to best serve the shot.

Postvis, like previs, can be accomplished with the facility that will be doing the final shots or with a separate team of artists who work on site with the production team and whose sole purpose is to create the previs and postvis for the project. A combination of the two, using the inherent strengths of both the off-site facility and the in-house team, will usually be most effective.

For example, because previs is generally a full-CG creation, most previs artists don’t specialize in the tasks associated with live-action plates such as camera tracking, roto, and paint work. As a result, it makes good sense to send the plates selected for postvis to the visual effects facilities that will be doing the final work. And, if the postvis plates end up in the final cut, this gets the facility way ahead of the game by addressing these tasks early in the post process.

Additionally, because the visual effects facilities have artists who specialize in these types of tasks, they will be much faster at producing camera tracking curves and getting that data back into the hands of the postvis team working on site with the production team. This, in turn, allows the postvis artists to concentrate on the postvis tasks they specialize in, such as modeling, texturing, rigging, and animation.

Because of the very iterative nature of previs and postvis, full-time artists specializing in them tend to be very fast and are able to turn out multiple iterations of shots routinely. For this reason, it is quite beneficial to have the previs and postvis teams on location in the production offices, where they can work closely with the VFX Supervisor, the editor, and quite often, the director to get fast and direct feedback.

Some visual effects facilities have full-time previs/postvis units as well, but if they are supervised by the facility’s internal team rather than directly by the production team, there can be, by its very nature, a longer lag in getting shots for review to production and, in turn, getting their feedback to the artists at the facility. The result is an unnecessary slowdown of the process.

In the case of an off-site team doing the previs/postvis, some effective solutions to meeting the requirements of a fast feedback loop include daily in-person visits from the production VFX Supervisor and a high-bandwidth link between the off-site previs/postvis unit and production so that editorial can cut in the daily shot updates for the production team to review.

Another effective technique features the use of a parallel minicut that tracks with editorial’s main cut but lives within the facility doing the previs/postvis. Using the mini-cut, new versions of the shots can be reviewed in context at the facility without waiting for editorial to process it. These techniques, combined with the use of real-time playback video conferencing sessions, such as Cinesync, can greatly enhance the lines of communication and shorten the feedback loop time.

However, the visual effects facility could choose to send its own previs/postvis artists to work on site with production, thus removing any significant differences between using an independent team or the vendor’s team. It is all about getting a great many iterations and fast feedback to get the most value for your time and money!

Sometimes very rough postvis is performed by the editorial department using the tools available in their nonlinear editing system, such as Avid or Final Cut. This has the advantage of being fast and tied directly to the editor, so it will be clear what they have in mind for the shot(s). However, the disadvantage of this type of postvis is that it can be extremely rough, and more importantly, it is separated from the realities and technical requirements of a final visual effects shot, meaning that it may not be reproducible in the real world of visual effects or may require a great deal more frame-by-frame work to create it. Because of these disadvantages, this form of postvis should be used with restraint. It is important not to fall in love with a shot that may look promising in its rough form but that will not work at the higher quality levels necessary for the final film.

The differences between postvis and formal animation blocking might appear to be small at first glance, but they are, in reality, quite significant in terms of the time and attention to detail spent on each shot. When doing postvis, it is common to have an extremely simple and light animation rig¹⁸ as a means of increasing animation speed. However, sometimes a visual effects facility will tend to use a lighter version of a very complex and tricked out animation rig to carry them all the way through to final animation, which can slow down the speed of animator iterations and eat up valuable time.

Animation blocking for the real visual effects shot needs to deal with the technical issues related to the animation, such as feet being planted firmly on the ground and ensuring that neither the feet nor any other part of a character’s body passes through any objects found in the live-action plates. By contrast, the only technical issues associated with postvis are using the correct camera lens and object scale and fixing small technical issues such as animation pops and large-scale sliding that are jarring enough to take the viewer out of the edit/story when viewing the sequence.

In general, for postvis, if it doesn’t disrupt the storytelling, leave it alone and move on to the next shot. This luxury does not exist for animation blocking, and as a result, that takes more time and care to create.

Another benefit of the formal postvis stage is that it gives the director, editor, and studio a complete version of all of the visual effects shots to cut into the film at a relatively early stage in the post-production process. This, in turn, may be used for studio and audience screenings as well. Additionally, it provides continuity across each sequence for the look of the models, textures, and lighting, which is an extremely important issue to keep the viewers focused on the storytelling rather than the progress of the visual effects work!

For example, when viewing the most updated version of the facility’s work in the edited project on any given day, there might be a grayscale animation cut next to a shot with first pass of lighting, which is cut next to a shot of a particle test, and so on. This is jarring and will interrupt the story being told. Therefore, it might be better to use the postvis material at this stage to help smooth over the visual effects and allow the story to be told without interruption. Of course, even though it is important to be reviewing and commenting on all the latest visual effects work in context, this is not conducive to screenings where the story must be judged. In fact, even if there was a version of all the first passes of lighting for a particular CG character in each shot, this could be more jarring to the viewer if the work is not yet photoreal than it would be to use the postvis look—which the viewer will immediately accept as a work in progress. The worst thing is to have the studio or test audience think that the early and in-progress visual effects shots are what the characters will actually look like in the final film!

Naturally, as the cut progresses, shots will continue to be omitted, added, or changed in terms of length, speed ramps, and framing. With a dedicated postvis team, it doesn’t take very long to add or change shots to keep the cut up-to-date, whereas with a visual effects facility team, it can be quite disrupting to try to reschedule the artists from their already assigned shots to go and fix a postvis shot every time a shot changes.

Figure 2.1 presents an example from 10,000 BC (2008) of a frame from a shot, showing its progress from previs to postvis to final.

Figure 2.1 Previs, postvis, and final from 10,000 BC (2008). (10,000 BC © Warner Bros. Entertainment Inc. All rights reserved.)

CAUTIONS AND SUGGESTIONS FOR GOOD PRACTICE

Mat Beck

The Perils of Previs!

For all that previs has to offer, its very power makes the process vulnerable to misuse. There are a number of problem areas to be aware of—but, fortunately, they can generally be avoided by observing certain standard practices. Below is a list of possible perils—with each followed by a suggested rule to help those using and creating previs to evade that particular trap.

Some of the following rules apply to the consumers of previs—the directors, writers, and other collaborators who use the previs to help them tell their story. Other rules apply more to the artists and companies that actually create the previs. However, everyone involved should understand both sides of the process so that previs can serve the story and the movie as effectively as possible.

Peril #1: Excessive Cost for the Previs Itself

Often, a principal goal of previs is to find ways to budget and schedule more efficiently. But as with any process that has limitless possibilities, previs can lead to too many hours spent noodling and refining. Therefore, one pitfall to watch out for is excessive expenditures (of both time and money) on the previs itself.

One of the principal ways to control those expenditures is to think carefully about which sequences in a film will benefit the most from previs. The larger the scope of the production effort necessary to capture a shot or sequence, the greater the value in prevising it. Also, the longer it will take to produce the final version of a shot or sequence, the greater the benefit of previs, because it will not only guide the subsequent work but can serve as a stand-in for purposes of editing, test screening, and so on. Choose your battles and work on areas with the biggest implications for savings in visual effects, set construction, production time, and so on.

It is also critically important to define exactly what is desired from previs. Is it being used as a sales tool (as in pitchvis)? Is it a tool to develop broad ideas? Is it meant to generate very specific technical information? Different purposes call for different approaches. For example, when previs is being used only to develop ideas, it doesn’t have to be as concerned with exact technical accuracy, but if the shots or sequences are meant to evaluate feasibility or to help various departments prepare to execute a sequence, then it is essential to be technically accurate.

With a specific goal in mind, it’s then possible to choose the right tool for doing the previs. Although computer-generated previs is the most powerful and current tool, it is important to remember that traditional techniques are still valid and can be extremely efficient. Storyboards or animated storyboards can show framing action and timing issues and can also serve as a precursor to more elaborate techniques. Rough “saddle-back” previs that can happen on a scout or stage walk can be extremely useful: A director, director of photography, or VFX Supervisor can use a video camera—or a digital still camera that records video—to perform a rough move that matches the director’s description. A camera with readable lens markings is useful for this, because the previs lens can be translated to the production lens with a calculation that adjusts for the difference in the sizes of the taking apertures. The goal is to use a focal length for the previs lens that has the same field of view as the selected production lens. Numerous computer and smartphone apps (e.g., pCAM) can perform the lens conversion; it is most helpful to concentrate on the width of the format when converting. It is convenient when a previs camera has virtually the same aperture width as the production camera (e.g., Nikon D300s versus Super 35mm) because the lens focal lengths will correspond almost exactly.

If lens markings are not available, it is possible to make a simple calibration of the field of view by setting a frame with a director’s finder corresponding to the final camera, noting two landmarks at either side of the frame, and then matching that field of view with the previs camera.

From there, it is a simple process to insert a few props (paper plates and toy store ants served in a recent scout) or stand-ins to get a sense of the rhythm and scope of a scene. Other forms of previsualization in the recent past have featured the director and DP acting out a fight scene on the set while being photographed by the VFX Supervisor. The point is that previs does not always have to be a computer-generated version of the shot or sequence.

Finally, previs software packages are available for the do-it-yourself previs artist/filmmaker. However, it is beyond the scope of this chapter to evaluate them.

Rule #1: Predetermine the scope and goals of the previs, as well as the appropriate tools and techniques for the task.

Peril #2: Too Many Choices—Stalling Out on the Details

Previs is a powerful tool, but with the exception of virtual production (described below), doing previs is not the same thing as making the movie. Just because you have the power to explore every choice doesn’t mean you should. It’s the bones of a sequence that are important. Excessive refinement of shot subtleties can get seductive—and expensive. For example, although the movements of a virtual character in a previs can be extensively tweaked for an acting performance, a real actor on set is going to do something different—and most often should be allowed to.

Rule #2: Use previs to set up the general structure of a sequence, not to tighten every nut and bolt.

Peril #3: Personnel Disconnects

One of the great powers of previs is the way in which it can facilitate clear communication. Partly, that means that effective previs has to be grounded in the technically correct world of the production. But it also means that previs should be grounded in the expertise of those who will be employed to make the movie. Besides the director, the most important people in this process are the director of photography, the production designer, the VFX Supervisor, and the editor. Previs that doesn’t include their input runs the risk that shots and sequences will be created that break the laws of physics—basic reality—or exceed the capability of the equipment and that therefore will not be achievable by those key departments, and it also risks the possibility that talented members of the production will feel alienated and resentful that their years of experience are being ignored.

Rule #3: Involve key department heads early.

Peril #4: Financial Disconnects

A script can be written so that it vastly exceeds the available budget for a movie, and a previs sequence can sometimes do the same. It is important for the previs process to include constant input from key department heads, including the VFX Producer and VFX Supervisor, as well as the Producer, Production Manager, etc., so that feedback about estimated costs is gained. Prevising a sequence that is unaffordable within the project’s budget is no more effective than writing such a sequence.

Rule #4: Use the previs to control the budget, not inflate it.

Peril #5: Practical and Technical Disconnects

Not all previs has to be technical previs, where every measurement is perfectly accurate. But previs that does not conform to the world of production well enough to be doable in the real world is a recipe for disaster.

Technically, accurate previs simply means that the virtual space matches the real world. At the risk of stressing the obvious, remember that even if previs is purely animated in a computer, it must by definition anticipate a real production. Any disconnect between the virtual world of the previs and the actual world of production can result in serious problems. In the real world, buildings are not 6 inches tall. Cars don’t drive 500 mph. Cameras have real dimensions and cannot be mounted inside a bridge abutment (without a lot of additional expense). This is one reason why it is so useful to model actual camera, grip, and other production equipment and use those models when working in virtual space. A cool-looking previs move that requires a 500-foot Technocrane moving 1000 feet per second is a move toward major disappointment on set.

If you want to cheat physics for greater impact in the final composite, that is fine, but do not cheat the physics of the things that will really be on set, such as cameras, cranes, cars, people, etc. A corollary: Do not animate the world. This means that a virtual environment should match the real world in camera motion as well. A camera and/or a person may fly down a street, but don’t keep the camera static and make the street fly past the camera.

Rule #5: Base your previs on real-world dimensions, with real-world parameters of camera movement.

Rule #5A: Don’t cheat on what is possible to make a shot more exciting.

Rule #5B: Make sure the image parameters are accurate as well. Keep in mind your final output format. Things like aspect ratio, frame rate, shutter angle, dimensions of camera back, etc., should match the real image-gathering equipment. (In the newer generation of video, the problem of the nonsquare pixel should not rear its head, but be sure to avoid it.) Similarly, it is always a time-saver to use the package of lenses anticipated by the camera department. This in turn is connected to rule #5C:

Rule #5C: Make the modeled camera-support equipment accurate. It is extremely useful for the hierarchy of pan, tilt, and roll embodied in the real camera head to be matched in the virtual previs. It is optimal to model the crane, dollies, etc., that will move the camera.

Peril #6: Not Enough Room for Creativity

The power of previs is its ability to anticipate the possibilities of production—that is, to define a shot or sequence from the millions of possible options. Ironically, in doing previs it is also important to remain open to possibilities that may present themselves on the set when the real crew, equipment, and actors are there. Don’t fall in love with the previs to the extent that possible improvements are rejected during production or post-production.

This is related to rule #2 above, but it is slightly different in that the cost is not financial but creative. Here, the restraint should be psychological: The structure of the previs should ideally leave some room for serendipity.

In addition, conditions on set may change the aesthetic of the shot. For instance, a point of view (POV) from a car that seems too slow at a low-resolution render can seem quite a bit faster with more visual information from the high-resolution real world, or even a higher resolution rendering.

Rule #6: Don’t fall in love with the temp—it’s only a previs. Don’t be so worried about implementation that you foreclose options.

Rule #6A: Leave room for iterations. Often the greatest creativity comes from the ability to try different versions. Make sure that your previs system and/or previs provider is nimble enough to turn out a number of iterations if needed. If working in 3D animation, use artists sufficiently skilled to come up with solutions quickly.

Peril #7: Not Using the Previs to Its Potential

Having been warned about excessive reliance on every aspect of the previs, also be warned about not using it enough. In the heat of production, many plans can go awry. Previs represents an exceptionally powerful form of planning—and a previs that ultimately is not used represents a plan wasted; and to the extent that other people have relied on it, it represents work that is wasted.

Rule #7: Don’t spend time, money, and energy on previs if you are ultimately going to ignore it. Plans are often meant to be broken—and sometimes thrown out—but don’t junk this one without good reason.

Passing the Work On

Quite often—although not always—shots that are prevised are visual effects shots as well. Keep in mind that previs may be created by separate companies, a separate department, or just separate personnel or even the same personnel at a different time. They do not always come from the visual effects team, company, or individuals. Regardless, it is important that good communication between these companies or individuals be maintained so that preliminary stages of the work and the later high-resolution completed shots can flow through the pipeline without creating confusion. So, there are rules that help preserve the work that was done and build on it through the process. Many of these rules come from the ASC/ADG/VES Joint Technology Subcommittee on Previsualization and reflect the concerns of the people who are exclusively practitioners of the previs art:

1.  If the previs team can build an environment using low-res assets that can be replaced with high-res versions later on, significant benefits will be gained by preserving the original animation.

2.  Maintain a library of assets that the production and subsequent visual effects vendors can use.

3.  Preserve key frames if possible—that is, do not bake out¹⁹ animation. This allows changes to be made to the previsualized action without starting over from scratch—saving time and frustration.

4.  If possible, use the same rigs for characters that will be used later in final animation. This is difficult to achieve, but it’s not impossible and the benefits are obvious. Animation files from the previs become useful in the final action. [However, do not do this if the resultant animation is so expensive (render intensive) that it reduces the ability to do multiple iterations.]

5.  When doing previs, use a software package that can carry over to subsequent visual effects production work.

Important caveat: There are two values that are often in conflict in previs: preservability versus disposability.

It is useful to pass on work that has been done to avoid reinventing the wheel in later stages. It is also important, in the effort to preserve what has been done, not to weigh down the process so much that it excessively constrains creativity or the number of iterations. Sometimes it is just better to start over, and one should allow for that possibility.

For practitioners of previs, the following 14 “commandments” of previs are offered. These were originally presented by the joint ASC/ADG/VES Subcommittee at the 5D Design Conference in October 2008²⁰:

  1. Always use real-world scale.

  2. Know your final output format.

  3. Match your DP’s lens package.

  4. Work within real-world constraints (if applicable).

  5. Establish and enforce a set of organizational standards and workflow procedures.

  6. Foster interdepartmental communication.

  7. Play “nice” with others.

  8. Do not animate the world.

  9. Understand film language.

10. Be open to constructive criticism.

11. Always remember the end product.

12. Create shots with sufficient heads and tails.

13. Know how to work within a given time frame.

14. Understand budgetary factors.

The Role of the VFX Supervisor in Previs

The glory and curse of VFX Supervisors is that they are always in the middle: balanced between the horns of multiple technical and creative dilemmas—between solving the right now and anticipating the future, between what can be imagined and what can be done in time, between good enough and tantalizingly close to perfect, between what can be saved and what must be thrown away—between the magic that can be controlled and the magic that just happens.

The challenge and fun and misery and triumph are in finding the balance between all those competing values. It is one of the great challenges of film (and life). Previs can be the vessel that allows exploration of the space between those extremes without committing too soon to one lesser solution—thereby expanding our creative universe.

THE FUTURE OF PREVIS: ADVANCED TECHNIQUES

Mat Beck

As with most of filmmaking, the state of the art in previs is a moving target. The advancing technology is likely to increase the speed and power of the process at the same time that it broadens its reach into new areas.

One area advancing rapidly is in the technology of data input. The techniques for gathering data for the performance, for the environment, and for camera movement are all advancing rapidly.

Environment Input

The technology for inputting data for creation of virtual space is already well established. Photogrammetry employs photographs of a real-world object from a variety of vantage points to create a 3D computer-generated image of, for example, a building or room. A scan of a room or neighborhood using an automatic laser rangefinder can generate a point cloud, which can be converted into a 3D space that accurately represents a set or location. Exterior scans are commonly linked up with satellite data to help build the large space. As the technology becomes more powerful, expect a broader use of it, including more application to such processes as virtual scouting.

Character Input

Motion capture (MoCap) is effective and broadly used as an input technique, and it is becoming more so. MoCap tracks the movements of real-life performers through the use of electronic or, more commonly, optical reference points on key parts of their bodies. The data that is gathered can then be applied to computer-generated characters existing in the virtual world.

This results in animation that is not only less labor intensive to create but also potentially more realistic. Although many effects and previs companies have their own proprietary tools for doing motion capture, there are also third-party companies that sell motion capture suits, cameras, and software.

The combination of a premodeled virtual space and real-time rendering means it is possible to get feedback as the performer moves through the virtual world. On the MoCap stage, scaffolding or steps can stand in for architecture or terrain that can be climbed in virtual space.

The addition of props with tracking markers on the MoCap stage allows the performer to interact with elements of that space. For example, a cardboard tube identified by the software as a tree can be picked up by the performer, and a display will show, in real time, a beast uprooting that tree in a virtual city street. It is not a high-res city street, but the resolution is only going to increase with time. This is the technology used in The Adventures of Tintin (2011) and Avatar (2009) to direct action.

Sometimes performance can be captured through the fingers of an experienced puppeteer. The Jim Henson Company has a system that uses MoCap performers to drive characters’ body movements, while their facial expressions are driven by puppeteers controlling Waldo rigs that capture subtle movements of their fingers and hands. (Waldos were named after a Robert Heinlein short story character with a handicap who uses devices to extend his own physical abilities.)

Camera Input

The characters in the scene are not the only performers whose movements can be captured. A virtual camera can also be tracked and moved through the scene, either contemporaneously with a performance or after the scene is created. This removes the creative barrier that a director may feel while driving a camera through mouse clicks. The director can carry a video camera, a display monitor, or even just a box with tracking markers through a MoCap space to create the movement desired. The software tracks the stand-in camera through the real MoCap volume of space and then flies a virtual camera through the virtual space, displaying the result either on a monitor or on the display in the director’s hand. The software can smooth movements or scale them, such that a gesture of the operator’s arm becomes a 30-foot crane move or an aerial flyover. Directors will often program one master camera along with the scene as it is being recorded and then later go to a smaller, cheaper MoCap stage to record coverage of additional camera angles as the established scene is played back.

It is also possible to track a real camera’s motion on a real set. Traditionally, this was done using encoders on heads, cranes, and/or dollies. Newer techniques have had success employing sensors on the camera that report angle and movement and that track on-set markers for position. More advanced techniques using MoCap or gaming techniques can be expected.

Gaming Techniques

As noted earlier, faster previs is better previs, because quality and creativity go up with the number of iterations. And game engines (which rely heavily on accelerated graphics hardware processing rather than a main CPU) continue to get faster. Many companies (e.g., ILM) are making great strides applying game engines to previs. The most successful implementations of this require the ability to transfer the data generated—geometry, texture, lighting, and movement—to high-end CG programs for high-res rendering.

Beyond faster processing time, a gaming-based system allows for camera control through the gaming console or wand—a fast and economical use of existing—and advancing—technology.

On-Set Previs

The ability to render previs composites in real time, combined with on-set data on camera position and attitude, allows for onset previs, while still making it possible for the sequences to later be finished using high-end renderers for polished final versions. The speed of this kind of work—made possible by faster processors, more powerful software, and optimized use of graphics hardware—offers directors more on-set feedback on the interaction between practical and virtual elements. It allows a scene to be framed for the 20-foot monster that will appear in the final film. It is previs and postvis at the same time. As systems get even faster, there will be more of what has already started to appear: simple composites being declared final as they are generated on stage.

Lighting Previs

Another challenge in previs—and a particular concern for cinematographers—is that the lights available in the computergenerated world of previs have been unrelated to those in the real world. In the past, with more primitive graphics, previs was more about composition and action. As previs becomes more powerful, it can include more attention to look. Because of this, cinematographers may worry that once lighting is set in the previs world, they could be tied into a look that is impossible to realize in real life. However, with increased power comes increased flexibility. Software is already available that previsualizes lighting for concert venues; as the software evolves and becomes capable of simulating the variety of lighting instruments available on set and as the power of processors allows for more and more detail on the figures being lit, expect that lighting previs will have an increasing impact—and that cinematographers will play a greater role in the previs process.

3D Stereo Previs

In a 3D stereo project, the sense of depth is controlled largely by two variables: (1) the interocular distance—the distance between the two cameras or “eyes” looking at the scene, and (2) the point of convergence—that is, the point in Z space (distance from the viewer) where the images from the two cameras overlap exactly. At the risk of some oversimplification, the interocular determines the overall depth of the scene, whereas altering the point of convergence determines how close the scene appears to the viewer. The viewer’s eyes are constantly adjusting their amount of toe-in to resolve the scene and place the elements in space. When the eyes are forced to make too many radical adjustments too quickly, it can lead to eyestrain and headache—and eventually to the belief that 3D movies just aren’t any fun to watch. Although images can be right/left offset in post-production to help finesse convergence, the interocular distance set on stage cannot be changed. The use of true 3D previs for 3D movies means that it is possible to pre-edit such sequences and ensure that there is maximum continuity of those depth cues.

Besides giving depth cues, the convergence is also (much like focus) a cue to the audience as to what the filmmaker wants them to look at in a scene. Previs can allow experimentation so that 3D stereo is a storytelling aid, not a distraction.

Virtual Production

If the movie never actually involves real shooting on a stage or set but goes directly from previs to CG rendering with virtual sets and characters, then the question presents itself: Is the previs still previs, or is it making the movie?

Such projects as James Cameron’s Avatar (2009) and Steven Spielberg’s The Adventures of Tintin (2011) use virtually every advanced previs technique. They employ full-on virtual production sets with MoCap tracking for characters, for set pieces, and for the camera as well as on-set rendering of the entire scene. In many cases these sessions become part of the production process. All of this technology is so expensive that it is important to go in with a plan of what is going to be shot. So, ironically, the filmmakers often “previs” the virtual production day. Cameron calls it precap. Peter Jackson has videotaped real people acting out scenes before using motion capture to drive animated characters. So, ironically, humans are now sometimes used to stand in for computer characters instead of the other way around.

This is another example of how advancing technology is altering the traditional definitions and job categories in modern production. The techniques of previs, which were once confined to pre-production, now sometimes begin before greenlight and continue until a week before the premiere, and sometimes replace the entire traditional production cycle.

One unifying aspect is the concept of a virtual production space, originally suggested by Alex McDowell, which serves as a common meeting ground for many of the crafts. This space—and the data contained in it—could begin to be built at the very inception of the ideas and persevere past release into marketing and merchandising.

The most dramatic possibilities for previs may involve grander visions that go well beyond how most people are using the technology these days—ways of creating a vision of production with new jobs, less obvious boundaries between crafts, and a whole new philosophy of filmmaking.

For example, as games become more like movies and movies become more like games, it is easy to imagine more blurring of lines. Perhaps as the tools for visualization become more powerful, they will continue to spread from planning to production to becoming a part of the actual enjoyment of the movie/ride/game. The visualization process will no longer be pre or post; it will have become part of the interactive entertainment experience.

Whatever new developments arrive, anything that previs techniques can do to facilitate the creative process of imaginative people and then transmit their visions to an engaged audience is likely to be a hit with everyone on both sides of the screen—whether a screen is involved or not.

CAMERA ANGLE PROJECTION

Steven D. Katz
Introduction by Bill Taylor

Drawing What the Lens Sees

Steven Katz describes techniques devised by Harold Michelson, a top production designer who worked on many important visual effects films—The Birds (1963) and Star Trek: The Motion Picture (1979), to name only two. Only simple drafting tools are required. The article is available on The VES Handbook of Visual Effects’ companion website (www.VESHandbookofVFX.com) and shows, step by step, how to use plan and view drawings of a set to create a two-point perspective drawing that shows what the camera will see from any given distance, with any lens. Katz also demonstrates Michelson’s inverse procedure: how to find the camera position and lens focal length from a still photograph or a frame enlargement of any subject (such as a room or building) where two perspective vanishing points can be discovered. The inverse procedure is particularly valuable when visual effects must be incorporated into a scene for which camera data was not recorded or was lost.

The demands on art department personnel sometimes exceed the available time, so it is quite valuable to be able to derive these answers simply—for example, when the visual effects team needs to know exactly where to put their cameras to match a storyboard or rendering or how big a green screen must be to cover the action. Knowledge of these basic projection techniques will prove invaluable to the VFX Supervisor or VFX DP, if only to better communicate with the production designer and his or her team.

This section is reprinted from the book Film Directing Shot by Shot: Visualizing from Concept to Screen²¹ with the permission of the author, Steven D. Katz, and the publisher, Michael Wiese. The illustrations were redrawn for The VES Handbook website through the generosity of Mr. Katz. Visit www.VESHandbookofVFX.com for the complete article and its illustrations.

¹ Scene: a progression of shots taking place in one location. Shot: a continuous and uninterrupted action on film. Cut: the edited footage. Sequence: a collection of scenes that make up a section in a film.

² Special effects covers effects work done live on the set, such as fire and breaking props. Visual effects covers effects done in post-production.

³ Plates: filmed shots to be used for visual effects. Plate photography refers to filming those shots.

⁴ Turnovers: edited and locked sequences that are delivered to the visual effects company to work on.

⁵ Clean plates: filmed versions of shots without actors or major action. These are used to make any rig removal easier in post-production.

⁶ Greenlit: approved for full production with funding.

⁷ Also known as cinematographer.

⁸ Another abbreviation is DOE

⁹ The first assistant director is also known as the 1st AD.

¹⁰ Refers to both the person who scouts the locations and the process of visiting the locations.

¹¹ Special Interest Group on Graphics and Interactive Techniques.

¹² Cinefex is a magazine devoted to visual effects.

¹³ 24p: video shot at 24 frames per second (fps), the same as film. Most NTSC video is 60i (approximately 60 fields per second). PAL video is 50i (50 fields per second).

¹⁴ 2D is represented with only height and width (as in a still image). XY tracking is sufficient for 2D motion tracking.

¹⁵ 2.5D is a cross between 2D and 3D. It provides the illusion of 3D without being fully 3D and is usually done in CG by projecting images onto very simple 3D shapes.

¹⁶ With substantial help and input from Marty Kline and John Scheele in original drafts.

¹⁷ Curtis Clark ASC, Chris Edwards, Ron Frankel, Colin Green, Joel Hynek, Marty Kline, Alex McDowell, Jeff Okun, and John Scheele all had critical input in generating and refining the definitions of previs.

¹⁸ Animation rig: CG structure built for the model and used by the animator as a type of skeleton to pose the animation model. A light rig would be a simple rig, without extras, that would make moving the animation model fast.

¹⁹ Bake out: to build in, lock, or render certain settings that make it impossible to make adjustments later.

²⁰ List of commandments supplied courtesy of Peter Nofz.

²¹ Reprinted from Film Directing Shot by Shot, © 1991 Steven D. Katz, Published by Michael Wiese Productions, www.mwp.com