GLOSSARY

This glossary is intended to be a practical guide to words commonly used in the visual effects field. It includes not only well-defined technical terms but also a number of colloquialisms that are often used within the industry. The visual effects industry is still a fairly new, volatile field. As such, any attempt to define the terminology that is in use within this discipline risks rapid obsolescence. What’s more, many terms used in the visual effects world can be rather ambiguous, or at least very context dependent. This is due in no small part to the fact that visual effects is a mesh of so many different disciplines. Terms from the fields of traditional animation, computer animation, image processing, photography, computer science (both hardware and software), art, special effects, visual effects, electronics, optics, physics, film, television, video games, and multimedia have all become part of the visual effects lexicon. We have attempted to give some idea of how multiple-definition terms might be interpreted depending on the situation in which they are used.

You will find that many entries will need to resort to the use of other visual effects terms in their definitions. In most cases, if there is a word within a given definition that is also defined elsewhere in this glossary, that word is printed in bold. The exceptions to this rule are those words (such as digital or color) that are used so often that it would be cumbersome to note their every occurrence.

The majority of this Glossary was provided by Ron Brinkman.

Words from the Stereoscopic Glossary (provided by Lenny Lipton) have been added with a designation of “(stereo)” at the beginning of the entry.

A

Academy aperture: A specific 35mm film framing.

Academy leader: The standardized length of film attached by the lab at the head and tail of release prints that meets the standards specified by the Academy of Motion Picture Arts and Sciences (AMPAS). The leader contains a countdown running from 8 to a single frame of 2, which is accompanied by a pop on the soundtrack.

Academy of Motion Picture Arts and Sciences (AMPAS): The professional organization that includes branches for almost every area of filmmaking and encourages continued artistic and technical research and development in the industry.

accommodation: The focusing of the eyes—or more properly, the ability of the eyes’ lenses to change shape in order to focus.

accommodation/vergence relationship: The learned relationship established through early experience between the focusing of the eyes and verging of the eyes when looking at a particular object point in the visual world. This is also commonly called the accommodation/convergence relationship (or the convergence/accommodation relationship).

ACM: Abbreviation for Association for Computing Machinery.

ACM SIGGRAPH: See SIGGRAPH.

acquisition format: A term used to describe the film format used to capture images. For example, Cinemascope and Super 35 are often used to capture images when the desired delivery format is 2.35:1 (often referred to as 2.35 format).

active region: The portion of a video signal that is used for actual image information, as opposed to blanking, closed captioning, time code, etc.

AD: Assistant Director.

ADR: Abbreviation for automated dialogue replacement. A process in which a performer replaces his or her previously recorded dialogue by respeaking the lines in sync to picture or by recording new dialogue in sync to picture.

affine: Any linear geometric transformation including pan, rotate, scale, and shear.

AIFF: Abbreviation for Audio Interchange File Format. A standard file format for storing audio data.

AIM: Refers to a value measured in the Laboratory Aim Density (LAD) printing control method. By exposing a LAD patch, the value of the exposure of that piece of film can be determined. Kodak publishes suggested density tolerances for each type of film in the duplicating and print system.

algorithm: A procedure or set of instructions for solving a problem or accomplishing a particular goal.

aliasing: An artifact that is due to limited resolution.

alpha channel: The portion of a four-channel image that is used to store transparency information.

ambient light: For computer graphics (CG), a directionless light source that uniformly distributes light in all directions, illuminating objects equally regardless of their surface orientation. CG ambient lighting is used as an inexpensive way to simulate the indirect illumination that occurs in the real world when light bounces off of other objects in the environment.

ambient occlusion: A CG shading method that uses a type of global illumination to better compute self-shadowing of objects. Often used in compositing as part of a multiple-pass rendering workflow.

American Cinematographer Manual: A manual, published by the American Society of Cinematographers, that is considered to be the industry Bible for cinematographers and anyone else involved in the field.

American Society of Cinematographers (ASC): The nonprofit organization dedicated to the continued advancement of the art of cinematography through technical and artistic growth. See also British Society of Cinematographers (BSC), Canadian Society of Cinematographers (CSC).

anaglyph: A stereoscopic image that requires the use of anaglyph glasses to view properly.

anaglyph: (stereo) Wavelength selection using complementary colored images and color filters to filter or pass the appropriate perspective views to the appropriate eyes.

anaglyph glasses: A type of 3D glasses that uses two different lens colors, usually red and blue, to control the images that are seen by each eye in a stereoscopic image. See also flicker glasses, polarized glasses.

analog: Information/data that is continuously variable, without discrete steps or quantization, as opposed to digital.

anamorphic: Any distorted image that can be undistorted to restore it to its original format.

anamorphic format: A film format characterized by the fact that the image captured on the negative is horizontally squeezed by the use of a special lens. It is later unsqueezed at projection time by the appropriate amount. For most 35mm feature-film work, the standard anamorphic format produces a 2.35:1 aspect ratio when projected. See Cinemascope, Panavision.

anamorphic lens: A lens that changes the width-to-height relationship of the original image. The most common anamorphic camera lenses in film work compress the horizontal axis by 50%. See Cinemascope.

animated: Having characteristics that change over time.

animatic: A rough animation that gives some idea about the timing of a sequence. Essentially a moving storyboard. See previs.

animation: Moving imagery that is created on a frame-by-frame basis. This may be accomplished via the use of computers or with more traditional cel animation techniques.

animation rig: CG structure built for the CG model and used by an animator as a type of skeleton to pose the animation model.

animator: A person responsible for producing animations.

anisotropic: Having properties (such as color or reflectivity) that differ based on the direction of measurement.

answer print: The first print from the lab containing synchronized image and sound and which has had all of the scenes color balanced.

antialiasing: Techniques used to mitigate the artifacts caused by a lack of sufficient resolution.

aperture: (1) In a lens, the size of the opening that light passes through (usually given in terms of its f-stop or t-stop). (2) In a camera body, the mask opening that defines the area of film that will be exposed on each frame. (3) In a projector, the mask opening that defines the area of the frame that will be projected.

API: Abbreviation for application programming interface. An interface implemented by a software program to enable interaction with other software, much in the same way that a user interface facilitates interaction between humans and computers. APIs are implemented by applications, libraries, and operating systems to determine the vocabulary and calling conventions the programmer should employ to use their services. It may include specifications for routines, data structures, object classes, and protocols used to communicate between the consumer and implementer of the API.

apparent motion: The natural ability of the eye to perceive motion in a series of images that are played back quickly enough. See also persistence of vision.

articulate matte: A matte whose shape changes over time and which is designed to accurately follow the contours of the object to which it corresponds.

artifact: A (usually undesirable) item in an image that is a side effect of the process used to generate or modify that image.

ASA rating: A standard numerical rating for specifying a film’s sensitivity to light. ASA refers to the American Standards Association, now known as the American National Standards Institute, or ANSI. Many manufacturers now use their own specific exposure index instead. See also DIN rating, ISO index.

ASC Manual: See American Cinematographer Manual.

ASCII file: See ASCII.

ASCII: Abbreviation for American Standard for Computer Information Interchange. Pure and simple text file based on an American standard. A very common alphanumeric text interchange format. The term is used colloquially to refer to data that is stored in a text format that does not require a special program to decode and is usually somewhat comprehensible to a human reader.

aspect ratio: A single number that is the result of dividing the width of an image by its height. The units used to measure the width and height are irrelevant, since they will cancel when divided together to give a unitless result. See also pixel aspect ratio.

Association for Computing Machinery: An organization, founded in 1947, that is the world’s first educational and scientific computing society. SIGGRAPH is one of the many special interest groups within the ACM.

atmosphere: A depth cue that causes objects to decrease in contrast as they move into the distance.

autostereoscopic: (stereo) Sometimes called auto-stereo, which can be confused with a car sound system.

B

background: In a composite, the bottom element over which all others are added. In general, the background makes up the majority of the image.

backing color: The color of the uniform background that is used when shooting an element for traveling matte extraction.

BAFTA: Abbreviation for the British Academy of Film and Television Arts.

Bake in: Term used to mean that whatever settings, composite layers, color, animation, and so on that have been used, have been permanently set in the shot. For example, “Do not bake in any bad animation or you will never be able to change it.”

Baked out: To output in a format that is fixed. In this case the model is no longer able to be animated but exists essentially as a 3D model for each frame.

banding: An artifact that appears in areas of a color gradient where the lack of sufficient color resolution causes noticeable bands instead of a smooth transition. Also known as contouring. See also Mach banding.

barrel distortion: Distortion of a lens that causes straight lines to bend away from the center of the image.

base: The transparent material (usually cellulose acetate) on which emulsions are applied to make photographic film. Note that a base is generally not completely transparent, but rather has a slight characteristic color that may need to be compensated for when scanning.

batch compositing: A method of compositing that entails the creation of a script or set of instructions that will be executed at a later time, without the need for a graphical user interface.

beamsplitter: (stereo) Technically this is a couple of prisms cemented together with a semi-silvered layer to split a light beam into two halves. For the rig used for stereo-cinematography, a thin sheet of glass that is semi-silvered is used in the optical path. Such a device is more properly called a pellicule (or pellicle).

beauty pass: (1) In multiple-pass photography, the pass of the object that contains the most color and detail, as compared with the matte pass, reflection pass, or shadow pass. Also called the color pass. (2) In multiple-pass rendering, the CG element that contains the most color and detail information. See also light pass, matte pass, shadow pass, and reflection pass.

Bézier curve: a curved line or path defined by mathematical equations. It was named after Pierre Bézier, a French mathematician and engineer who developed this method of computer drawing in the late 1960s while working for the car manufacturer Renault. The most basic Bézier curve is made up of two end points and control handles attached to each node. The control handles define the shape of the curve on either side of the common node.

BG: Abbreviation for background.

bicubic interpolation: A method of interpolation based on an average of the 16 nearest neighbors. See also linear interpolation, bilinear interpolation.

bilinear interpolation: A method of interpolation based on an average of the four nearest neighbors. See also linear interpolation, bicubic interpolation.

binocular: (stereo) Two eyes. The term binocular stereopsis (twoeyed solid seeing) is used in some psychology books for the depth sense more simply described as stereopsis.

bipack: The process of loading two pieces of film in such a way that they travel through the same movement of the camera at the same time. Sometimes referred to as sandwiching.

bit: The basic unit for representing data in a digital environment. A bit can have only one of two values: 0 or 1.

bit depth: A way of specifying the color resolution in an image by measuring the number of bits devoted to each component of the pixels in the image.

bitmapped image: An image that consists of a rectangular, twodimensional array of pixels. The standard method for representing an image in a digital format.

black point: (1) On a piece of film, the measured density in the area of greatest opacity. (2) In a digital image, the numerical value that corresponds to the darkest area that will be represented when the image is eventually viewed in its final form.

bleach bypass: A general term used to describe a number of film processing techniques offered by various labs, in which the bleaching function done during normal processing is partially or completely skipped as a means of increasing contrast and reducing saturation. Also called ENR.

blue record: The layer of the film that captures blue light.

blue screen: (1) Commonly used as a generic term that refers to bluescreen photography or any similar process, which may use other colors as well as blue. (2) Literally, a screen of some sort of blue material that is suspended behind an object for which a matte is to be extracted. Ideally, the blue screen appears to the camera as a completely uniform blue field. (Note that in this handbook the standard is to use blue screen to designate the screen itself and the term bluescreen to designate the process.)

blue spill: Any contamination of the foreground subject by light reflected from the blue screen in front of which it is placed. See also spill, green spill.

bluescreen photography: The process of photographing an object in front of a blue screen with the intention of extracting a matte for that object using various keying and/or color-difference techniques.

bokeh: A photographic term referring to the appearance of point-of-light sources in an out-of-focus area of an image produced by a camera lens using a shallow depth of field.

bounce light: Light that is reflected or bounced off of other objects in a scene before it reaches the subject.

box filter: A specific digital filter that is often used when resampling a digital image. The box filter is fast but fairly low quality.

British Academy of Film and Television Arts (BAFTA): The British version of the American Academy of Motion Picture Arts and Sciences (AMPAS).

British Society of Cinematographers (BSC): The British version of the American Society of Cinematographers (ASC). See also Canadian Society of Cinematographers (CSC).

B-spline: Simply a generalization of a Bézier curve.

burn-in: Photographic double exposure of an element over a previously exposed piece of film.

C

camera aperture: The opening in a camera lens. It is usually referred to in f-stops or t-stops. It allows a specific amount of light to hit the film or sensor, thus resulting in an image.

camera frustum: Basically, what the camera sees. See also frustum and viewing frustum.

camera mapping: A CG technique in which an image is projected from the camera onto a 3D object. This technique is useful for re-creating a simulation of a 3D environment using 2D photographic elements. Also called projection mapping.

Canadian Society of Cinematographers (CSC): The British version of the American Society of Cinematographers (ASC). See also British Society of Cinematographers (BSC).

cardboard effect: (stereo) An effect in which a viewer perceives the objects and characters in a 3D composition to be flat (as if on cardboard cutouts). This effect is often the result of using a lens with a long focal length.

CBB: Abbreviation for could be better. When a shot has a few minor technical or aesthetic adjustments to be made, but the delivery date is close at hand, this term is used to final a shot with the caveat that it will be improved at a later date if time and budget permit.

CC: Abbreviation for color correction.

CCD: Abbreviation for charge-coupled device, a light-sensitive semiconductor that is often used in scanners and video cameras to capture an image.

cel animation: Animation that is the result of sequences of images drawn on individual clear acetate cels. Many aspects of traditional cel animation are now being supplemented by digital techniques.

center extraction: A term used to describe any process, such as masking or cropping, that is used to extract the centered portion of the original image to produce the final viewing format.

centroid: The geometric center of an object.

CG: Abbreviation for computer graphics.

CG feature: Any feature film created entirely with computer-generated imagery.

CG Supervisor: Abbreviation for Computer Graphics Supervisor. (See the list of VES-approved titles in Appendix B.)

CGI: See computer-generated imagery.

channel: For a given image, the subimage that is composed only of the values from a single component of each pixel.

characteristic curve: A curve that plots the relationship between light falling on a piece of film and the resulting density of the developed image.

chroma-keying: A keying technique that allows one to separate an object from its background based on colors that are unique to either the foreground or background.

chromatic aberration: An image artifact that is caused by the fact that different wavelengths of light are bent by slightly different amounts as they pass through a lens. The artifact is usually seen as a color shift along sharply delineated edges in an image.

chromatic resolution: Another term for color resolution.

chrominance: The color portion of a video signal, carrying the hue and saturation values. See also luminance.

Cinemascope: An anamorphic film format that produces an image with an aspect ratio of 2.35:1. Although Cinemascope (or CinemaScope) was originally a specific process developed by Twentieth Century Fox in the 1950s, it has become a generic term for the 2.35 anamorphic format. The most common lenses used for this purpose today are produced by Panavision.

cinematographer: An individual who is experienced in the art of capturing images on camera. The main cinematographer for a film is the Director of Photography.

Cineon: A specific image file format used most often in film compositing work.

circle of confusion: The size of the circle to which an idealized point will diverge when the lens is focused at different depths. Used as a way to measure the focus of a lens.

circular polarization: (stereo) A form of polarized light in which the tip of the electric vector of the light ray moves through a corkscrew in space.

clean plate: A plate that differs from the primary plate only in that it does not contain the subject(s) in the frame.

clip: A small piece of film, often clipped from a longer shot, that can be used as a reference for color, lighting, etc.

clipping: The process (intentional or otherwise) whereby data above or below a certain threshold is removed or lost. With digital images, this usually translates to colors outside a specific range.

clone: In digital paint, a method of copying information from one region of an image to another.

cloud tank: A large water-filled glass enclosure that is used to create clouds and other atmospheric effects. The clouds are usually produced by injecting some opaque liquid (such as white paint) into the water.

CLUT: Abbreviation for color lookup table.

CMY: Abbreviation for cyan, magenta, and yellow, the three complementary colors, or a method of specifying the colors in an image based on a mix of these three components.

codec: A specific type of compression used on images.

color bars: Standard test patterns used in video to determine the quality of a video signal. Color bars consist of equal-width bars representing black, white, red, green, blue, yellow, cyan, and magenta. These colors are generally represented at 75% of their pure value.

color contamination: A term used to describe a backing color, such as blue screen or green screen, that is contaminated with one of the other primary colors. Color contamination can make the job of matte extraction much more difficult.

color correction: Any process that alters the perceived color balance of an image.

color difference method: A compositing technique that utilizes the difference in color between the different channels of an image in order to extract a matte. The technique relies on the subject being photographed in front of a uniformly colored background, such as a blue screen.

color lookup table: A lookup table that is specifically designed to modify color.

color management: A global term used to describe the process of producing consistent color across a range of software and devices.

color resolution: The amount of data allocated for specifying the value of an individual color in an image. See also bit depth.

color script: (stereo) Colors used for scene-to-scene and character design to match image depth requirements per script.

color space: Any method for representing the color in an image. Usually based on certain components such as RGB, HSV, etc.

color temperature: A method of specifying color based on an absolute temperature scale, degrees Kelvin (K). The color is equivalent to the color of light that would be emitted if a pure black object were heated to that temperature. Higher color temperatures are more blue; lower temperatures are more red.

color timer or grader: A person who adjusts the scene-to-scene color continuity when preparing the final print of a film.

color timing or grading: The color balance of a particular image or scene, or the process of color correcting and balancing that image or scene.

color wedge: A series of images that feature incremental alterations in the color of a certain element (or sometimes the entire frame) for the purpose of choosing a final value for the color of that element.

complementary color: The color that results when the primary color is subtracted from white.

complementary matte: The matte that results when the primary matte is inverted.

component: One of the elements that is used to define the color of a pixel. In most digital images, the pixel color is specified in terms of its red, green, and blue components.

component video: Video signal in which various aspects of color such as luminance and chrominance are maintained separately.

composite video: Video signal in which the color elements are all combined (encoded) into a single signal.

compositing: The manipulated combination of at least two source images to produce an integrated result.

compositing engine: Within a package used for compositing, the code that is responsible for the actual image-processing operations, in contrast to other code that may deal with the user interface, file input/output, etc.

Compositing Supervisor: The individual responsible for the aesthetic and technical supervision of all digital composites created for a project. The Compositing Supervisor leads a team of compositors. (See the list of VES-approved titles in Appendix B.)

compositor: A person who creates composites. (See the list of VES-approved titles in Appendix B.)

compression ratio: The ratio of the data sizes between an uncompressed element and its compressed equivalent.

computer-generated imagery (CGI): An image or images created or manipulated with the aid of a computer. Often used to refer specifically to 3D computer animation, although it is really a much broader term.

computer graphics: An image or images created or manipulated with the aid of a computer.

Computer Graphics Supervisor: The person responsible for determining the aesthetic and technical solutions, software selections, and overall pipeline for the 3D work on a project. (See the list of VES-approved titles in Appendix B.)

conform: The process of matching raw, original footage with some edited version of that footage.

conjugate points: (stereo) See corresponding points.

contact shadow: A shadow that is cast from one object when it is in direct contact with another object, as opposed to a shadow that is cast on a distant surface.

continuity: The smooth flow of action or events from one shot or scene to the next, without any indication that the different shots/scenes may have been photographed at different times or processed differently.

contouring: An artifact that results from not having enough color resolution to properly represent a color gradient. See also Mach banding.

contrast: The ratio of the brightest tones in an image to the darkest.

control points: The specific points that are interpreted to define the shape of a curve.

convergence: (stereo) The inward rotation of the eyes, in the horizontal direction, producing fusion. The more general term is vergence, which includes inward and outward rotation. The term has also been used, confusingly, to describe the movement of left and right image fields or the rotation (toe-in) of camera heads.

conversion: (stereo) Also known as synthesis. A process by which a planar image is turned into a stereoscopic image—a flat image into a 3D image.

convolution filter: A matrix of numbers used to control the weighted averaging performed in a convolve operation. Sometimes also referred to as a convolution mask.

convolution kernel: The group of pixels that will be considered when performing a convolve operation. Generally the size of the kernel is the only worry, which is usually a square matrix with an odd number of elements in each dimension. The most common kernel size is 3 × 3. Occasionally the term is used as a synonym for the convolution filter.

convolution mask: See convolution filter.

convolve: An image processing operation that involves the specialized averaging of a neighborhood of pixels using a convolution filter. Also known as spatial convolution.

cool: A nonexact term that is used to describe an image that is biased toward the blue portion of the spectrum.

corresponding points: (stereo) The image points of the left and right fields referring to the same point on the object. The distance between the corresponding points on the projection screen is defined as parallax. Also known as conjugate or homologous points.

CPU: Abbreviation for central processing unit, the computational heart of a computer.

crawling: An undesirable artifact characterized by edges that do not remain stable over time.

creature shop: Any facility that creates prosthetics, animatronics, puppets, robotics, and creatures for use in a film.

cropping: The removal (intentionally or otherwise) of part of an image that is outside a specific boundary.

crosstalk: (stereo) Incomplete isolation of the left and right image channels so that one leaks (leakage) or bleeds into the other. Looks like a double exposure. Crosstalk is a physical entity and can be objectively measured, whereas ghosting is a subjective term.

C-scope: Abbreviation for Cinemascope.

C-stand: Common three-legged adjustable stand used by the grip department to hold things such as lighting flags.

cukaloris: Panel with irregular holes cut in it to project patterned shadows onto a subject. Also known as a kukaloris, cuke, or cookie.

cursor: A graphical marker, usually controlled by a device such as a mouse or a tablet pen, that is used to point to a position or object on a computer’s display.

curve editor: Any graphical user interface (GUI) module that allows the user to create and modify curves.

D

D1 format: A digital component video format. D1 is considered to be a nearly lossless format, although it does use 4:2:2 compression.

D2 format: A digital composite video format. D2 is a lower quality than D1, but is also significantly less expensive.

D5 format: A digital component video format. D5 is considered to be of the same quality as D1 and also has provisions for storing HDTV-format imagery.

dailies: Imagery produced during the previous day’s work or a meeting to view this work.

day for night: The process of shooting footage in daylight conditions with the intention of eventually presenting it as a nighttime scene. It may involve a combination of photographic, lighting, and digital post-processing techniques.

dB: Abbreviation for decibel.

DCI: Abbreviation for Digital Cinematography Initiative for Digital Projection.

decibel (dB): A unit of measurement that expresses a ratio using logarithmic scales to give results related to human perception.

decimation: The process of throwing away unnecessary information when reducing the size of an image.

deinterlace: The process of separating the two fields that make up a video image into two distinct images.

densitometer: Instrument used to measure the optical density of a piece of processed film.

density space: A nonlinear color representation that is based on the density of developed negative relative to the amount of light that reached it.

depth channel: Another term for the Z-channel.

depth cue: Information that helps to determine the distance of an object from the camera.

depth of field (DOF): The depth of field of a specific lens is the range of acceptable focus in front of and behind the primary focus setting. It is a function not only of the specific lens used but also of the distance from the lens to the primary focal plane and of the chosen aperture. Larger apertures will narrow the depth of field; smaller apertures will increase it.

depth of focus: A term that is often improperly used when one wishes to refer to the depth of field. Depth of focus is a specific term for the point behind the lens (inside the camera body) where a piece of film should be placed so that the image will be properly focused.

depth range: (stereo) A term that applies to stereoscopic images created with cameras. The limits are defined as the range of distances in camera space from the background point, producing maximum acceptable positive parallax, to the foreground point, producing maximum acceptable negative parallax. See also parallax budget.

desaturation: A term that describes the removal or loss of color in an image. A completely desaturated image would consist only of shades of gray.

detail generator: An adjustment available on some video cameras that introduces additional sharpening into the captured image.

DI: Abbreviation for digital intermediate.

difference matte: A matte created by subtracting an image in which the subject is present from an otherwise identical image in which it is not present.

diffusion: An effect, caused by atmosphere or special filters placed on the lens, that is characterized by a scattering of light, elevated dark areas, and an overall softer look.

digital: A method of representing data via discrete, well-defined samples, as opposed to analog.

digital artist: Any artist who creates and manipulates images digitally. The term encompasses both 2D and 3D artists and can be synonymous with the various titles used, such as CG Artist, Technical Director (TD), Compositor, Matte Painter, Character Animator, etc. (See the list of VES-approved titles in Appendix B.)

digital compositing: The digitally manipulated combination of at least two source images to produce an integrated result.

Digital Effects Supervisor: The individual responsible for the creation of all digital effects work required for a production. The DFX Supervisor oversees the work of the CG Supervisor and the Compositing Supervisor and reports directly to the Visual Effects Supervisor. (See the list of VES-approved titles in Appendix B.)

digital intermediate (DI): A high-quality digital version of a film that is used to finalize all color balancing issues.

digitization: The process of sampling any analog subject to produce a digital representation. Within the field of digital compositing, usually refers to the process of converting a video or film source to digital information.

dilation: An image-processing technique that results in brighter areas of the image increasing in size and darker areas decreasing. See also erosion.

DIN rating: A standard numerical rating for specifying a film’s sensitivity to light. DIN is an abbreviation for Deutsche Industrie Norm (German Industry Standard). Many manufacturers now use their own specific exposure index instead. See also ASA rating, ISO index.

diopter: An auxiliary lens that goes in front of the camera lens to allow for close-up photography.

Dirac filter: Another name for an impulse filter.

director: The person with the primary responsibility for overseeing the creative aspects of a project or production.

disparity: (stereo) The distance between conjugate points on overlaid retinae, sometimes called retinal disparity. The corresponding term for the display screen is parallax.

dissolve: A specific transition effect in which one scene gradually fades out at the same time that a second scene fades in. Halfway through a linear dissolve the image will be a 50% mix of both scenes.

dither: A method for representing more colors than would normally be available with a given palette. Dithering uses combinations of colored pixels and relies on the fact that the human eye will average them together and interpret the result as a new intermediate color.

D-max: See maximum density.

D-min: See minimum density.

DOD: Abbreviation for domain of definition.

DOF: Abbreviation for depth of field.

domain of definition (DOD): A (usually rectangular) region that defines the maximum boundaries of useful information in an image. Generally, everything outside of the DOD will have a value of 0 in all channels of the image. The DOD is usually determined automatically, as opposed to a region of interest.

dots per inch (DPI): A common method for measuring spatial resolution in the print industry. The horizontal and vertical scales are assumed to be equal, unless specified otherwise.

double exposure (DX): In the optical world, a double exposure is accomplished by exposing two different images onto a single negative. The result is a mixture of the two images. In the digital world, this effect is accomplished by mathematically averaging the two images.

double framing: The process of duplicating and repeating every frame in an image sequence. The result is a new image sequence that appears to be moving at half the original speed. Also known as double printing.

DoP, DP: Director of Photography. Also see cinematographer.

DPI: Abbreviation for dots per inch.

DPX: Abbreviation for Digital Picture Exchange, a specific image file format.

drop frame: Video footage in which two frames are dropped every minute except the tenth. It is used to compensate for the fact that time code works at exactly 30 frames per second, but NTSC video runs at only 29.97 fps.

dubbing: The process of making a copy of a videotape.

dust busting: The term used to describe the process of removing dirt and scratches from scanned imagery.

DVE: Abbreviation for digital video effect that usually refers to any of a number of geometric transformations that are typically performed by specialized real-time video equipment. Examples of a DVE move include animated pans, rotations, or flips, as well as various hardware-specific effects such as page turns or customized wipes.

DX: Abbreviation for double exposure.

dynamic range: (1) The range of brightness values in a scene or an image, from brightest to darkest, often expressed as a ratio. (2) In a digital image, the total number of different colors in the image.

dynamic resolution: Another term for color resolution.

E

ECU: Abbreviation for extreme close-up.

edge detection algorithm: An algorithm used to enhance or isolate transition areas, or edges, in an image.

edge matte: A specialized matte that includes only the outlines or borders of an object.

edge numbers: Sequential numbers printed along the edge of a piece of film (outside of the perforations) by the manufacturer to help identify particular frames.

edge quality: A term used to describe the characteristics of the edges of an element that has been matted into a scene.

editing: The process of assembling shots and scenes into a final product, making decisions about their length and ordering.

EDL: Abbreviation for edit decision list, which is a text file that lists the order and length of each shot in a sequence or movie.

E-fan: Special effects fan commonly used to generate and control a specific volume of air.

effects animation: A term that usually refers to elements that were created via cel animation or digital rotoscoping techniques but are not character related. Common examples include sparks, lightning, or smoke.

effects filter: Any of a number of different optical filters that can introduce diffusion, flares, glows, etc., in front of the camera. Very problematic when shooting bluescreen elements.

EI: Abbreviation for exposure index.

8-bit image: In the visual effects world, this term typically refers to any image containing 8 bits of color information per channel.

8mm film: A narrow-gauge film that contains 74 frames per foot.

eight-perf: A nickname for the VistaVision film format that comes from the fact that each VistaVision frame has eight perforations along each edge.

element: A discrete image or sequence of images that will be added to a composite.

emulsion: The light-sensitive material that is applied to a transparent base to create photographic film.

encoder: (1) A piece of video equipment that combines a component video signal into a composite video signal. (2) A generalized term used to refer to a number of different data capture devices, usually ones that convert measurements into digital data.

ENR: Named for its inventor, Ernesto Novelli Rimo, a former control department operator at Technicolor Rome who designed the technique for Vittorio Storaro, ASC, AIC to use on Warren Beatty’s 1981 film Reds. ENR is a proprietary color-positive developing technique that utilizes an additional black-and-white developing bath inserted at an appropriate stage of a print’s processing in order to retain silver. After the film has been bleached, but prior to the silver being fixed out of the film, this extra bath allows for a controlled amount of silver to be re-developed, adding density in the areas with the most exposure–primarily the blacks. See also bleach bypass.

erosion: An image-processing technique that results in darker areas of the image increasing in size and brighter areas decreasing. See also dilation.

E-split: See exposure split.

Estar film stock: A polyester film base that is much more rugged than an acetate film base. It is thinner and much stronger than acetate. It can damage the moving parts of a camera or projector if it jams, whereas acetate films will just tear. Its durability allows its use for compositing many takes of a scene or for longer wearing release prints.

exposure index (EI): A standardized, but manufacturer-specific, numerical rating system for specifying a film’s sensitivity to light. Several industry-standard systems are in use, including the ASA rating, the ISO index, and the DIN rating. To make it even more interesting, many manufacturers will specify a rating for both daylight lighting and tungsten lighting.

exposure latitude: Amount of over- or underexposure a given type of film can tolerate and still produce acceptable results.

exposure sheets: Sheets that tell the Oxberry camera, or down-shooter, cameraman in what order to layer and shoot the animation cels and for how many frames per cel, per layer. They do essentially the same thing for the optical printer cameraman: Indicate order of layout, exposure, length, and filtration of the elements to be rephotographed. (In animation also called x-sheets or dope sheets.)

exposure split: A simple split-screen shot in which multiple exposures of a given scene are combined in order to bring areas of widely divergent brightness into the same shot. Also known as an E-split.

exposure wedge: A series of images that feature incremental alterations in the exposure (brightness) of a certain element (or sometimes the entire frame) for the purpose of choosing a final value for the exposure of that element.

EXR: See OpenEXR.

extrastereoscopic cues: (stereo) Those depth cues appreciated by a person using only one eye. Also called monocular cues. They include interposition, geometric perspective, motion parallax, aerial perspective, relative size, shading, and textural gradient.

eye line: Specific direction in which the actor looks. In visual effects, usually a point that is frequently off camera to represent another actor or object.

F

FACS: Abbreviation for Facial Action Coding System, a method by which all the possible actions of the human face can be encoded.

fade: Decreasing the brightness of an image over time, eventually resulting in a black image.

fast Fourier transform (FFT): An algorithm for converting an image so that it is represented in terms of the magnitude and phase of the various frequencies that make up the image. Yes, there is a regular Fourier transform, but nobody uses it because it’s not ... fast.

FFT: Abbreviation for fast Fourier transform.

FG: Abbreviation for foreground.

field: (1) An image composed of either the even or odd scan lines of a video image. Two fields played sequentially will make up a video frame. (2) A unit of measure on a field chart.

field chart: A method of dividing an image into a grid so that certain areas of the frame can be specified by grid coordinates.

field dominance: The order in which the fields in an interlaced image are displayed. Essentially, whether the even or the odd field is displayed first for any given frame.

field of view (FOV ): The range of a scene that will be captured by a specific camera. FOV is usually measured as the number of horizontal degrees (out of 360), although a vertical field of view is also a valid measurement.

field-sequential: (stereo) In the context of cinema stereoscopy, the rapid alternation of left and right perspective views projected on the screen.

file format: A standardized description of how a piece of data (such as an image) is to be stored.

film gauge: The width of a particular film stock, that is, 16mm, 35mm, etc.

film-out: Term meaning the actual recording of the digital image data onto motion picture film.

film recorder: A device that is capable of transferring digital images to a piece of film negative.

film recording: The process of transferring digital images to a piece of film negative via the use of a film recorder.

film speed: A very context-dependent term that may refer to (1) the rate at which film is moving through a camera or a projector (24 frames per second in normal feature-film work) or to (2) the light sensitivity of the film itself. Slow-speed film is less light sensitive; high-speed film is more sensitive.

film weave: Irregular horizontal movement (generally undesirable) of a piece of film as it moves through a camera or projector.

filter: (1) A translucent material that is placed in front of a light or camera to modify the color that is transmitted. Certain of these optical filters may also be designed to introduce specific artifacts, such as diffusion, flares, etc. (2) Any of a number of algorithms used within the computer for sampling an image. Different filters can be used when transforming an image and can result in differing amounts of sharpness or artifacts. (3) The process of using either of the aforementioned types of filters.

final: The term given to a composite shot once it is considered complete and has been approved by the appropriate decision makers.

fix it in post: A phrase commonly used when time and/or conditions prohibit the ability to shoot a scene exactly as intended. Rather than delaying the production, a decision is made to shoot as quickly as possible and correct any problems during post-production, usually using visual effects techniques.

fixed matte: As opposed to a traveling matte, a fixed matte will not change position or shape during the shot.

flare: Any of a number of effects that will show up on an image as the result of a light source shining directly into the lens of a camera.

flashing: An optical process whereby an unprocessed negative is exposed to a small amount of light for the purpose of reducing the contrast or saturation of the scene that will eventually be photographed with that film. In the digital realm, flashing is the application of any number of nonspecific techniques to produce similar results. An image that appears to suffer from some of these characteristics is often referred to as appearing flashed.

flat: Another term for low contrast.

flat lens: Another term for a spherical lens. Sometimes also used as a relative term for measuring the distortion and exposure variance of any lens.

flatbed: A mechanical picture and sound editing machine on which multiple film rolls and audio tracks are loaded separately and lay flatly on a motorized table-like surface, allowing film editors smoother, quieter, and better viewing of the material for the purpose of editing and reviewing the edit. These machines were essentially the last improvements in editing equipment, following the Movieola, before nonlinear digital editing machines took over. They are now rarely if ever used. (Sometimes referred to as a KEM.)

flicker glasses: A type of 3D glasses that use an electronic shutter to block the light reaching each eye independently. By syncing the glasses to the projection device, alternate stereo pairs can be presented to the viewer in a fashion that simulates a stereoscopic scene. See also anaglyph glasses, polarized glasses.

flip: A simple geometric transform in which an image is mirrored about the X-axis so that it is now upside-down. This process is different from merely rotating the image 180 degrees.

float: A number defined with floating point precision.

floating point: A term used to describe a number in which no fixed number of digits must be used before or after a decimal point to describe a number, meaning that the decimal point can float.

floating windows: (stereo) Invented by Raymond and Nigel Spottiswoode, this is the use of printed vertical bands to create a surround to supplant the physical screen surround. The result is a so-called virtual window that is floating in space to eliminate the screen edge cue conflicts and to extend the parallax budget of the projected image.

flop: A simple geometric transform in which an image is mirrored about the y-axis.

focal length: A measure of the magnification power of a given lens, based on the distance from the center of the lens to the film. Also known as simply the length of a lens. A longer focal length will produce greater magnification than a shorter length.

focus: (1) To adjust a lens so that the image it produces is as sharp as possible. (2) The point in space behind a lens where this sharpness occurs.

folding: The process of consolidating discrete mathematical operations into a single function.

forced perspective: A technique used to create the illusion of increased depth in a scene by building more distant objects at a smaller scale than normal.

foreground: Usually the primary element to be added to a composite and placed over the background. A composite often has several foreground elements.

format: (1) The size, resolution, aspect ratio, etc., for a given image. (2) The file format for a given image. (3) The physical medium (such as film, video, etc.) used to capture or display an image sequence. (4) A multitude of additional variations and subcategories of the first three definitions.

four-perf: A nickname for the standard 35mm film format that refers to the fact that each frame spans four pairs of perforations.

four-point track: A type of 2D tracking in which four points are selected from a sequence of images to extract an approximation of an object’s movement relative to the camera. Allows for corner pinning techniques.

4:1:1 compression: A method of encoding the data needed to represent an image by sampling Y (luminance) for every pixel but removing every other UV (chroma) pixel in both the horizontal and vertical directions.

4:2:2 compression: A method of encoding the data needed to represent an image by sampling Y (luminance) for every pixel but removing every other UV (chroma) pixel in the horizontal direction.

4:4:4 compression: A method of encoding the data needed to represent an image by sampling Y (luminance) and UV (chroma) for every pixel in the image.

4k resolution: A general term referring to any digital image containing an X resolution of approximately 4096 pixels. The actual dimensions of a 2k image depend on the aspect ratio of the imagery. A common 4k resolution used in visual effects when working with full-aperture framing is 4096 × 3112.

FOV: Abbreviation for field of view.

fps: Abbreviation for frames per second. See also frame rate.

fractal compression: A lossy compression algorithm that is based on repeated use of scaled and rotated pixel patterns.

frame: A single image that is usually part of a group designed to be viewed as a moving sequence.

frame rate: The rate at which sequences of images are captured or displayed. The frame rate is usually measured in frames per second, or fps.

freeze: The process of stopping the action. In digital compositing, this is usually accomplished by repeating the same frame for a duration of time.

freeze frame: A single frame that is held for a duration of time.

fringing: An artifact of the matting process in which a foreground element has a noticeable (usually bright) outline.

frustum: Term commonly used in computer graphics to describe the 3D region that is visible on the screen (which is formed by a clipped pyramid); in particular, frustum culling is a method of hidden surface determination.

frustum culling: Or view frustum culling is the process of removing objects that lie completely outside the viewing frustum from the rendering process. Rendering these objects would be a waste of time since they are not directly visible.

f-stop: A measurement of the aperture of a lens.

full aperture: A specific 35mm film framing, also known as camera aperture.

fusion: (stereo) The combination, by the mind, of the left and right images—seen by the left and right eyes—into a single image.

G

gamma: (1) In film, a measure of the contrast of an image or emulsion, based on the slope of the straight-line portion of the characteristic curve. (2) An adjustment applied to a video monitor to compensate for its nonlinear response to a signal. (3) A digital effect used to modify the apparent brightness of an image.

gamut: The range of colors that any given device or format is able to display or represent.

garbage matte: A rough, simple matte that isolates unwanted elements from the primary element in an image.

Gaussian blur: A specific method for blurring an image based on a Gaussian filter.

Gaussian filter: A specific digital filter that is often used when resampling an image.

gel: Abbreviation for gelatin filter, a flexible colored optical filter.

generation loss: The loss of quality of an image due to repeated duplication. Generation loss is significantly reduced and in some cases completely eliminated when dealing with digital images.

geometric transformation: An effect that causes some or all of the pixels in a given image to change their current location. Such effects include translation, rotation, scaling, warping, and various specialized distortion effects.

ghosting: (stereo) Term used to describe the perception of crosstalk.

GIF: Abbreviation for Graphics Interchange Format, a specific image file format.

global illumination: A general term used to describe the modeling of all of the reflected and transmitted light that originates from every surface in a scene.

glue code: Code that ties different parts of the pipeline together, whether it is data interchange between programs that write different file formats or interprocess control of one piece of the pipeline by another.

G-matte: Abbreviation for garbage matte.

gobo: See cukaloris.

Go-Motion photography: Technique that gives naturalistic motion blur when shooting miniatures. The camera shutter remains open with the motion control rig moving continuously through the shot.

grading: Another term for color timing, used primarily in Great Britain.

grain: The individual particles of silver halide in a piece of film that capture an image when exposed to light. Because the distribution and sensitivity of these particles are not uniform, they are perceived (particularly when projected) as causing a noticeable graininess. Different film stocks will have different visual grain characteristics.

graphical user interface (GUI): A user interface that utilizes images and other graphical elements to simplify the process of interacting with the software. Also known as the look and feel of the software.

gray card: A card (gray) usually designed to reflect about 18% of the light that strikes it; used as a reference for measuring exposure.

grayscale image: A completely desaturated image, with no color, only shades of gray.

greeblies: A term for small reusable model geometry components, from the term used by ILM to describe an assortment of detail pieces from kit-bashed commercial plastic model kits used on production models.

green-lit: A project that is approved to proceed into full production with funding.

green record: The layer of the film that captures green light.

green screen: Identical in use and concept to a blue screen (only it is green). (Note that in this handbook the standard is to use green screen to designate the screen itself and greenscreen to designate the process.)

green spill: Any contamination of the foreground subject by light reflected from the green screen in front of which it is placed. See also spill, blue spill.

guesstimate: A combination of a guess and an estimate that is used to qualify a quick or not particularly accurate budget, time, and technique approach.

GUI: Abbreviation for graphical user interface.

H

halation: A blurring or spreading of light around bright areas on a photographic image. Also seen as a glow around a bright object on a monitor or television screen. Most films have an anti-halation backing to keep the light from bouncing around in the camera and adding additional unwanted exposure—or halation.

handles: Extra frames at the beginning and end of a shot that are not intended for use in the final shot but are included in the composite in case the shot’s length changes slightly.

haptic arm: A force-feedback system. In computer graphics it sometimes takes the form of a pressure-sensitive stylus to be used with a computer tablet.

HD resolution: A general term referring to any digital image that contains the spatial resolution of one of the HDTV standards, of which 1920 × 1080 is the most common.

HDR: Abbreviation for high dynamic range.

HDRI: Abbreviation for high dynamic range imaging.

HDTV: High-definition television. A television standard with significantly greater spatial resolution than standard NTSC, PAL, or SECAM.

Hermite curve: A specific type of spline curve that allows for explicit control over the curve’s tangent at every control point.

high dynamic range (HDR): Related to imagery or devices that can deal with a larger than normal dynamic range.

high dynamic range imaging (HDRI): A technique for capturing the extended tonal range in a scene by shooting multiple pictures at different exposures and combining them into a single image file that can express a greater dynamic range than can be captured with current imaging technology.

high-pass filter: A spatial filter that enhances high-frequency detail. It is used as a method for sharpening an image.

histogram: A graphical representation of the distribution (usually frequency of occurrence) of a particular characteristic of the pixels in an image.

histogram equalization: An image-processing technique that adjusts the contrast in an image so that it fits into a certain range.

histogram sliding: Equivalent to adding a certain number to the values of every pixel in an image.

histogram stretching: Equivalent to multiplying the values of every pixel in an image by a certain amount.

HIT: (stereo) Horizontal image translation. The horizontal shifting of the two image fields to change the value of the parallax of corresponding points. The term convergence has been confusingly used to denote this concept.

HLS: Hue, luminance, and saturation. A method of specifying the colors in an image based on a mix of these three components.

hold: To stop the action by using the same frame repeatedly.

hold-out matte: A matte used to prevent a foreground element from completely obscuring an object in the background plate.

homologous points: (stereo) See corresponding points.

hot: A nonexact term for describing an image that is too bright. Completely unrelated to the terms warm and cool.

hot head: A computer-assisted camera mount head that can either record the pan and tilt of an operated camera or use previously recorded pan/tilt information to play back; that is, to drive the camera head mount to replicate the pan/tilt move. As the equipment improves, more axes are becoming recordable and capable of being played back to drive the camera.

HSB: Hue, saturation, and brightness. A method of specifying the colors in an image based on a mix of these three components.

HSI: Hue, saturation, and intensity. A method of specifying the colors in an image based on a mix of these three components.

HSL: Hue, saturation, and lightness. A method of specifying the colors in an image based on a mix of these three components.

HSV: Hue, saturation, and value. A method of specifying the colors in an image based on a mix of these three components.

hue: A specific color from the color spectrum, disregarding its saturation or value.

Huffman coding: A lossless image compression scheme. See also run-length encoding, JPEG, MPEG.

I

ICC: Abbreviation for International Color Consortium.

ILM: Abbreviation for Industrial Light & Magic.

image processing: The use of various tools and algorithms to modify digital images within a computer.

IMAX: A proprietary film capture/projection process that uses an extremely large-format negative.

impulse filter: A specific digital filter that is often used when resampling a digital image. It is considered to be the lowest quality, highest speed filter in common use. Also known as the Dirac filter or the nearest-neighbor filter.

in-betweening: The process of interpolating between the key frames of an animation sequence.

in-camera effects: Visual effects that are accomplished solely during principal photography, involving no additional postproduction.

indexed color: A method of storing image data, in which the value of the pixel refers to an entry in a table of available colors instead of a numerical specification of the color itself.

Industrial Light & Magic (ILM): A pioneering visual effects company that was the first to widely use digital compositing in feature-film work.

interactive lighting: Lighting in a scene that changes over time and responds to the activity within the environment.

interaxial distance: (stereo) The distance between camera lenses’ axes. See T. Also called interaxial separation.

interframe coding: The process used in MPEG encoding whereby intermediate images in a sequence are defined by their deviation from specific key frames.

interlacing: The technique used to produce video images whereby two alternating field images are displayed in rapid sequence so that they appear to produce a complete frame.

intermediate: General term used for copies (not necessarily first generation) of the original negative, which can be used as the source for duplicate copies. See interpositive, internegative.

internal accuracy: The measurement of the precision or bit depth that a software package uses to represent and modify image data.

International Color Consortium (ICC): The organization established for the purpose of standardizing color management across different platforms.

internegative (IN): Short for intermediate negative, a copy made from the interpositive through printing and developing.

interocular distance: The spacing between the eyes, usually referring to the human average of about 2.5 inches; an important factor for the production of a stereoscopic image.

interocular distance: (stereo) See “T.”

interpolation: The process of using certain rules or formulas to derive new data based on a set of existing data. See also bicubic interpolation, bilinear interpolation, linear interpolation.

interpositive (IP): Short for intermediate positive, a positive print made from the original negative for use in making internegatives. A positive film copy on negative film stock. It is used to protect a negative from overuse. From this interpositive, a duplicate negative may be made, when necessary. IPs usually retain a finer film grain than if the negative were printed to positive film stock and then back to negative film stock.

interpositive film stock: Orange-based motion picture film with a positive image made from the edited camera negative. The orange base provides special color characteristics that allow for more accurate color reproduction than if the IP had a clear base, as in print films.

interpupillary distance: (stereo) The distance between the eyes’ axes. See T. Also called interpupillary or interocular separation.

ISO index: A standard numerical rating for specifying a film’s sensitivity to light. ISO is the abbreviation for International Standards Organization. The ISO index actually incorporates both the American ASA rating and the European DIN rating. Many manufacturers now use their own specific exposure index instead. See also ASA rating, DIN rating.

J

JPEG: A (typically lossy) compression technique or a specific image format that utilizes this technique. JPEG is an abbreviation for the Joint Photographic Experts Group.

K

kernel: The group of pixels that will be considered when performing some kind of spatial filtering. See also convolution kernel.

key: (1) Another name for a matte. (2) The process of extracting a subject from its background by isolating it with its own matte and compositing it over a new background.

key code: See edge numbers.

keyer: A device or operation used for matte extraction or keying.

key frame: Any frame in which a particular aspect of an item (its size, location, color, etc.) is specifically defined. The frames that are not key frames will then contain interpolated values.

keyframe animation: The process of creating animation using key frames.

keyframing: Another term for keyframe animation.

keying: The process of algorithmically extracting an object from its background and combining it with a different background.

Keykode numbers: A specific form of edge numbers that was introduced by Kodak.

Keylight: The trade name of a color difference keyer developed by the Computer Film Company (CFC).

keystone distortion: A geometric distortion resulting when a rectangular plane is projected or photographed at an angle not perpendicular to the axis of the lens. The result is that the rectangle becomes trapezoidal. Also referred to as keystoning.

kukaloris: See cukaloris.

L

LAD: Abbreviation for Laboratory Aim Density (LAD) printing control method. By exposing a LAD patch, the value of the exposure of that piece of film can be determined. Kodak publishes suggested density tolerances for each type of film in the duplicating and print system.

large-format camera: Any camera designed to use wide-gauge films, such as 65mm film.

large-format film: Generally refers to any film larger than the standard 35mm film format.

latent image: The invisible image that exists on an exposed piece of negative that has not yet been developed.

layering operation: A global term referring to any compositing operation that integrates one element with another element based on their alpha channels or RGB values.

Leica camera: One of the finest still cameras made. Known for their quiet shutter and for great lenses that have amazing contrast and sharpness.

Leica lenses: The brand of lenses used on the animation cameras that photographed storyboards in the earliest Disney days.

lens artifact: Any artifact, such as a lens flare or chromatic aberration, that appears in an image as a result of the lens assembly.

lens assembly: Referring to the set of specially matched lenses that are assembled to form a single lens component in a standard camera lens.

lens flare: An artifact of a bright light shining directly into the lens assembly of a camera.

letterboxing: A method for displaying images that preserves the aspect ratio of the film as it was originally shot, using black to specify areas outside of the original frame.

light pass: (1) In multiple-pass photography, the pass of individual lights striking the subject, such as the key or fill, for later use in compositing. (2) In multiple-pass rendering, the CG element that represents the effects of a particular light striking the object. See also beauty pass, matte pass, reflection pass, shadow pass.

lighting reference: A stand-in object that can be used to judge the lighting in a scene.

linear color space: A color space in which the relationship between a pixel’s digital value and its visual brightness remains constant (linear) across the full gamut of black to white.

linear encoding: A method of converting the colors from the input image to an output image in an evenly distributed, linear way. Also referred to as linear mapping. See linear color space, nonlinear color space.

linear interpolation: A method of interpolation that is based on the average of the two nearest neighbors. See also bicubic interpolation, bilinear interpolation.

linear polarization: (stereo) A form of polarized light in which the tip of the electric vector of the light ray remains confined to a plane.

linear space: See linear color space.

locked cut: Term meaning that no more editing will be done on the shot, scene, or project; the edit is 100% complete.

locked-off camera: A camera whose position and lens settings do not change over the duration of the shot.

log space: Abbreviation for logarithmic color space, a nonlinear color space whose conversion function is similar to the curve produced by the logarithmic equation.

long lens: A relative term, in contrast to a short lens. Also known as a telephoto lens.

lookup table (LUT): An array of values used to convert data from an input value to a new output value. See also color lookup table.

lossless compression: A method of compressing and storing a digital image in such a fashion that the original image can be completely reconstructed without any data loss.

lossy compression: A method of compressing and storing a digital image in such a fashion that it is impossible to perfectly reconstruct the original image.

lowball bid: A very low bid based on extreme best case scenarios.

low-pass filter: A spatial filter that removes high-frequency detail. It is used as a method for blurring an image.

luma-keying: A matte-extraction technique that uses the luminance values in the image.

luminance: In common usage, synonymous with brightness. In the HSL color space, luminance is the weighted average of the red, green, and blue components.

LUT: Abbreviation for lookup table.

LZW compression: A lossless compression method that finds repeated patterns in blocks of pixels in an image. Variations of LZW compression are used in a number of image file formats, including GIF and TIFF. LZW stands for Lempel-Ziv-Welch.

M

Macbeth chart: An industry standard test chart made up of square color and gray patches.

Mach banding: An optical illusion (named after the physicist Ernst Mach) in which the eye perceives emphasized edges in areas of color transition. This illusion causes the eye to be more sensitive to contouring artifacts.

macro: (1) In the digital world, a combination of functions or effects that are grouped together to create a new effect. (2) A specialized lens that is capable of focusing at an extremely close distance to the subject.

mandrel: Form to replicate the volume and basic shape of an object for on-set interaction. The actual image of the object will be added in post-production. An example is a mandrel with the basic shape of a rhino used to smash in a wall that is later replaced with a CG rhino.

maquette: Very detailed physical sculpture of a creature or character.

mask: An image used to selectively restrict or modify certain image-processing operations on another image or the process of doing so.

matchmove: The process of extracting the camera move from a live-action plate in order to duplicate it in a CG environment. A matchmove is often created by hand as opposed to 3D tracking in which special software is used to help automate the process.

matte: An image used to define or control the transparency of another image. See also articulate matte, complementary matte, difference matte, edge matte, fixed matte, garbage matte, hold-out matte, rotoscoped matte, static matte, traveling matte.

matte channel: Another name for the alpha channel in a four-channel image.

matte extraction: Any process used to create a matte.

matte line: An artifact of the matting process wherein a foreground element has a noticeable outline.

matte painting: A hand-painted image, usually intended to be photorealistic, that is combined with live-action footage.

matte pass: (1) In multiple-pass photography, a pass that is lit in some high-contrast fashion so that it can be used as a matte during compositing. (2) In multiple-pass rendering, a separate render of the alpha channel of one of the objects in the scene for use during compositing. See also beauty pass, light pass, reflection pass, shadow pass.

maximum density: The point of exposure at which additional light (on the negative) will no longer affect the resulting image. The definitions of maximum and minimum density would be reversed if you were speaking of print (reversal) film instead of negative. Also known as D-max.

median filter: A specialized spatial filter that removes pixel anomalies by determining the median value in a group of neighboring pixels.

miniaturization: (stereo) Often occurs when a large interaxial separation is used for shots of people at medium distances or for photography of distant objects, like houses or hills. The perception of such images as miniatures is idiosyncratic and varies from person to person.

minimum density: The point of exposure just below the amount needed (on the negative) to start affecting the resulting image. The definitions of minimum and maximum density would be reversed if you were speaking of print (reversal) film instead of negative. Also known as D-min.

Mitchell filter: A specific digital filter that is often used when resampling a digital image. The Mitchell filter is particularly well suited to transforming images into a higher resolution than they were originally.

MoCap: Abbreviation for motion capture. A technique whereby an individual being’s performance is captured and translated for use in driving a CG being’s performance. Also known as performance capture.

moco: Abbreviation for motion control.

monochrome: An image that contains only a single hue, and the only variation is in the luminance of that hue. Typically, a monochrome image consists only of shades of gray.

monocular cues: (stereo) See extrastereoscopic cues.

morphing: A process in which two image sequences are warped (see warping) so that key features align as closely as possible and then a selective dissolve is applied to transition from the first sequence to the second. The result should be a seamless transformation between the two sequences.

MOS: Term used to mean there is no sync sound recorded for this take. Comes from the early days of filmmaking when the German director would shout out “Mit out Sound!”

motion artifact: A general term describing all forms of image artifacts due to motion, such as strobing or wagon wheeling.

motion blur: An artifact caused by the fact that a camera’s shutter is open for a finite duration as it captures an image. Any object that is moving during that time will appear blurred along the path that it was traveling.

motion control: A method of using computer-controlled mechanisms to drive an object’s movement so that it is continuously repeatable.

motion control camera: A camera whose position, orientation, and lens settings are motion controlled.

motion graphics: Animated graphic imagery that is done primarily to achieve a specific visual design rather than to produce photorealistic images.

Movieola: A self-contained mechanical film viewing device. Typically used by film editors, it allowed for rapid stopping, reversing, and vari-speeding of the film (and separate sound strips) for the purpose of editing and/or reviewing the cut. The large green machine had many conveniences built into it over the years, but due to the advent of nonlinear digital editing devices, it is no longer in use.

MPEG: A (typically lossy) compression technique specifically designed to deal with sequences of images or the format of the images produced by this technique. MPEG is an abbreviation for the Moving Picture Experts Group.

multimedia: A broad categorization that generally refers to some method of displaying information using sound and imagery simultaneously.

multiplane compositing: A technique that simulates a moving camera by automatically translating the different layers in a composite by an amount that is appropriate to their intended distance from this camera. Layers that are intended to appear farther away are moved by a smaller amount than layers that are intended to be nearer, producing a simulated parallax effect.

multiple-camera rig: (stereo) A technique commonly used in virtual 3D photography in which more than one stereo camera pair is used to photograph the scene. Individual objects in the scene are assigned to each camera pair with each one using unique stereoscopic parameters. Also describes the collection of camera pairs used to photograph such a scene.

multiple-pass photography: Any filming in which multiple exposures of the same subject are filmed, generally with different lighting setups. If the camera is moving, then it must be motion controlled to ensure accurate alignment between passes. Typical passes might include a beauty pass, matte pass, reflection pass, and shadow pass.

multiple-pass rendering: A technique in which a 3D object or scene is rendered in a series of separate images, each with different lighting or rendering characteristics. Typical passes might include color, shadow, reflection, key light, fill light, backlight. See also multiple-pass photography.

multiplexing: (stereo) The technique for placing the two images required for a stereoscopic display within an existing bandwidth.

N

naming conventions: The standardized names that are used within a facility to differentiate the various elements and files that are stored on disk for a project.

ND filter: See neutral density filter.

nearest-neighbor filter: Another term for the impulse filter.

neutral density filter: An optical filter that is designed to reduce the intensity of the light passing through it without affecting the color of the light.

Newton’s rings: An artifact, usually seen in optical printing, characterized by circular moiré patterns that appear in the image.

NG: Abbreviation for no good (e.g., that take was NG or no good).

nodal point: The point at which light entering a lens converges before it spreads again to form an image at the film plane. A nodal setup allows the camera to pan, tilt, and roll without creating any parallax shift between foreground and background elements.

node view: A view, available in most compositing software, that shows the hierarchical structure of the image-processing operations that will be used to generate a final composite.

nonlinear color space: A color space in which the relationship between a pixel’s digital value and its visual brightness does not remain constant (linear) across the full gamut of black to white.

nonlinear editing: Editing that does not require that the sequence be worked on sequentially.

nonlinear encoding: A method of converting the colors from an input image to an output image in a nonlinear way. See linear color space, nonlinear color space.

nonsquare pixel: A pixel whose width is not the same size as its height. The ratio of width to height is measured in terms of a pixel aspect ratio.

normalized value: A digital value that has been converted to fall within a specific range. With digital compositing, this is usually the range of 0 to 1.

NTSC: Abbreviation for National Television Systems Committee. Refers not only to the committee itself, but also to the standard that they established for color television in the United States and other countries. It carries 525 lines of information, played back at a rate of approximately 30 frames per second (actually 29.97). Due to its unreliable color reproduction ability, the initials are often said to stand for never the same color or never twice the same color.

NURBs: Abbreviation for nonuniform rational B-spline.

O

occlusion: State in which objects, or portions of objects, are not visible because they are blocked by other objects or portions of objects.

off-line compositing: Another term for batch compositing.

Omnimax: A proprietary film capture/projection process that uses the same large-format negative as the IMAX process but is designed for projection on the interior of a dome-shaped screen.

1:85: Common aspect ratio of width to the height of the image.

o-neg: Abbreviation for original negative.

one-point track: A type of 2D tracking in which a single point is selected in a sequence of images to extract an approximation of an object’s movement relative to the camera. Tracking a single point only allows for translational movements.

1k resolution: A general term referring to any digital image containing an X resolution of approximately 1024 pixels. The actual dimensions of the 1k image depends on the aspect ratio of the imagery.

on-line compositing: A method of compositing that uses a highly interactive hardware/software combination to quickly provide the results of every compositing operation. Distinguished from an off-line or batch compositing system.

on-set previs: Creates real-time (or near real-time) visualizations on location to help the director, visual effects 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. Also see previs, pitchvis, technical previs, and postvis.

opaque: The characteristic of an image that causes it to fully obscure any image that is behind it. Opaque is the opposite of transparent.

OpenEXR: A specific image file format designed for use with high dynamic range imagery.

OpenGL: Abbreviation for open graphics library. A standard specification defining a cross-language, cross-platform API for writing applications that produce 2D and 3D computer graphics. Programs that use OpenGL can leverage graphics cards to accelerate graphics.

optical compositing: The process of using an optical printer to produce composite imagery.

optical flow analysis: A method for procedurally determining the movement of objects in a sequence of images by examining the movement of smaller blocks of pixels within the image.

optical printer: A device used to combine one or more different film elements and rephotograph them onto a new piece of film.

original negative (o-neg): The first-generation negative that captured the original image directly from the scene. Later duplicates of this negative are known as intermediate negatives or internegatives.

orthographic: Representing a 3D object in two dimensions.

orthographic view: A view of a 3D scene rendered without any perspective—objects appear to be the same size regardless of their distance from the camera.

overcrank: Running a camera at a faster speed than the intended projection rate, resulting in projected footage that appears to move slower than normal. Footage shot at a faster-than-normal rate is said to have been shot overcranked. See also slow motion.

oversampling: Sampling data at a higher-than-normal resolution in order to mitigate sampling errors or inaccuracies from uncharacteristic data.

P

paint software: A program that allows the artist to “paint” directly onto an image in the computer using a device such as a tablet or a mouse.

paintbox: Usually used in the video post-production world as a generic term for a variety of paint and compositing devices.

PAL: Abbreviation for phase alternation by line. A standard for color television found in many European, African, and Asian countries. It carries 625 lines of resolution, played back at a rate of 25 frames per second.

palette: The range of colors available for use in any particular application. A system that uses 8 bits per channel would have a palette of more than 16 million colors.

pan and scan: A technique that is used to convert images shot with a widescreen film process to a less expansive video format. It generally involves selectively cropping the image to fit into the new frame, arbitrarily choosing what portions of the image are unnecessary.

pan and tile: A technique in which a series of images of a scene are stitched together to create a larger panoramic view of the scene.

Panavision: (1) A manufacturer of motion picture lenses and cameras. (2) The trade name for a specific widescreen process and lenses developed by the Panavision company. It is an anamorphic format that produces an image with a 2.35:1 aspect ratio. See also anamorphic format, Cinemascope.

Pantone Matching System (PMS): A color identification standard used in print work that contains more than 3000 different colors. Many computer graphics programs allow the user to select colors based on their PMS number.

parallax: The perceptual difference in an object’s location or spatial relationship when seen from different vantage points.

parallax: (stereo) The distance between conjugate points. It may be measured with a ruler or, given the distance of an observer from the screen, in terms of angular measure. In the latter case the parallax angle directly provides information about disparity.

parallax budget: (stereo) The range of parallax values, from maximum negative to maximum positive, that is within an acceptable range for comfortable viewing.

particle system: A 3D computer graphics technique that is used to create a large number of objects that obey well-defined behavioral rules. Useful not only for controlling multitudes of discrete objects such as asteroids or flocks of birds but also as a tool for creating natural phenomena such as fire or smoke.

pattern matching: Process by which missing image data is synthesized by continuing patterns that are found elsewhere in the image into the missing area. Also can be used for motion tracking.

peg registered: Special animation paper with special holes that fit over animation pegs on an animation stand to ensure proper registration of the paper. Also used with animation cels for the same purpose.

perf: Abbreviation for perforation.

perforation: One of the sprocket holes that runs along the edges of a piece of film. They are used to guide the film reliably through the camera. Also called a perf.

performance capture: A technique whereby an individual being’s performance is captured and translated for use in driving a CG being’s performance. Sometimes called MoCap.

periscope lens: A lens mounted to a tube that extends out from the camera (typically 20 inches or so) and can photograph objects at a 90-degree angle to the body of the camera. Also known as a snorkel lens.

Periwinkle effect: Technique for shooting wet-for-dry using an underwater bluescreen process. Invented by Jeffrey A. Okun and Thomas Boland.

persistence of vision: The characteristic of the human eye that allows it to continue to perceive an image for a fraction of a second after it disappears.

perspective: A term relating to the size and depth relationships of the objects in a scene.

perspective compensation: The use of a 2D geometric transformation to correct a 3D discrepancy.

photogrammetry: A method in which textured 3D geometry is created based on the analysis of multiple 2D images taken from different viewpoints.

photorealism: A global term used to describe CG images that cannot be distinguished from objects or scenes in the real world.

picture element: See pixel.

pincushion distortion: A type of lens distortion in which straight lines are bent inward toward the center of an image. See also barrel distortion.

pipeline: A well-defined set of processes for achieving a certain result.

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. Also see previs, technical previs, on-set previs, and postvis.

pixel: Originally an abbreviation for picture element, although the term pixel is generally considered to be an actual word nowadays. A digital image is composed of a rectangular array of individual colored points. Each one of these points is referred to as a pixel.

pixel analyzer: A tool available in most compositing and paint packages that allows the user to point the mouse over an area of pixels in order to get the specific or average color values for that portion of the image.

pixel aspect ratio: The width of a given pixel divided by its height. A number of image representation methods do not use pixels that have an equivalent width and height. The pixel aspect ratio is independent of a particular image’s aspect ratio. See also nonsquare pixels.

pixelation: An effect caused by displaying a bitmap or a section of a bitmap at such a large size that the individual pixels that make up the image are visible to the eye.

pixelation animation: Stop-motion technique in which live actors are used as a frame-by-frame subject in an animated film by repeatedly posing while one or more frame is taken and changing the pose slightly before the next frame or frames. The actor becomes a kind of living stop-motion puppet.

planar: (stereo) Flat; two dimensional. A planar image is one contained in a 2D space, but not necessarily one that appears flat. It may have all the depth cues except stereopsis.

plano-stereoscopic: (stereo) A stereoscopic projected image that is made up of two planar images.

plate: A piece of original photography that is intended to be used as an element in a composite.

playback speed: The rate (usually measured in frames per second) at which a sequence of images is displayed.

polarized glasses: 3D glasses that use polarizing filters to differentiate between the images sent to the right and left eyes in stereo films. See also flicker glasses, anaglyph glasses.

post-house: A facility where the post-production work takes place.

postmove: Referring to any move added to a plate via image transformations performed in compositing, as opposed to shooting the scene with the desired camera move.

posterization: An effect applied to an image that intentionally causes banding.

post-production: Work done once principal photography has been completed.

postvis: Combines digital elements and production photography to validate footage selection, provide placeholder shots for editorial, and refine effects design. Edits incorporating postvis sequences are often shown to test audiences for feedback and to producers and visual effects vendors for planning and budgeting. Also see previs, pitchvis, technical previs, and on-set previs.

practical effects: Effects that are accomplished live, without any post-production. Practical effects include explosions, artificial rain, and smoke.

precomp: Abbreviation for preliminary composite.

preliminary composite: Any intermediate imagery that is produced during the digital compositing process that can be saved and used as a new source element. Also called a precomp.

premultiplied image: An image whose red, green, and blue channels have been multiplied by a matte. Usually this matte is stored as the alpha channel of this image.

pre-production: Any planning, testing, or initial design that is done before actual production begins.

previs: Abbreviation for previsualization. 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. Also see pitchvis, technical previs, on-set previs, and postvis.

Primatte: A proprietary chroma-keying tool that can be used to extract a matte from an image shot in front of a uniform backing.

prime lens: A camera lens with a fixed focal length, as opposed to a zoom lens, which has a variable focal length.

print: A positive image that is suitable for viewing directly or for projection. Generally produced from an original or an intermediate negative.

procedural paint: A specialized form of paint software that can actually apply brush strokes and other paint processes over a sequence of images instead of just a single frame. Parameters for these painting effects can usually be animated as well.

processing: (1) The time spent by the computer as it computes any instructions that it has been given. (2) At a photo laboratory, the process of developing and printing a piece of film.

producer: Administrative head of a project. Responsible for budget, schedule, etc. (See the list of VES-approved titles in Appendix B.)

production sense: The near-mythical ability of an experienced digital artist to decide on the proper course of action when creating a visual effects shot.

progressive scan: A method of displaying an image that does not rely on interlacing.

projection mapping: See camera mapping.

projection speed: The playback speed for projected imagery.

proxy: A scaled-down image that is used as a stand-in for a higher resolution original.

pull a matte: The process of creating a matte for an object, usually through keying techniques.

pulldown: Shorthand for 3:2 pulldown.

pullup: Shorthand for 3:2 pullup.

Q

quantization: The process of assigning discrete digital values to samples taken from a continuous analog data set.

quantization artifact: A term generally used to refer to a visually noticeable artifact of the quantization process.

quantizing: Colloquial term for a quantization artifact.

R

Ramsdell rig: (stereo) First designed by Floyd Ramsdell. A rig that allows two cameras to be arranged in a way that provides the means for taking stereoscopic moving images, by use of a beamsplitter, to create an interocular separation that is the same distance apart as typical human eyes. See beamsplitter.

raster graphics: Image representation using a grid of pixels. Vector graphics uses line information to represent images.

raw stock: Unexposed, unprocessed film.

R&D: Abbreviation for research and development.

RDBMS: Abbreviation for relational database management system.

real time: (1) Displaying a sequence of images at the same speed as they will be viewed in their final form. (2) Computational processing that appears to be nearly instantaneous.

rear projection (RP): A compositing process in which the previously photographed background scene is projected onto a large translucent screen from behind while the foreground action takes place. The composite is thus considered an in-camera effect.

record: One of the red, green, or blue color-sensitive layers in a piece of film. Thus, the blue record is equivalent to a digital image’s blue channel.

red record: The layer of the film that captures red light.

reference spheres: Chrome and neutral gray globes, used on the set to visually record the placement of lights within a scene. CG artists later use the sphere(s) reference as a guide for placing CG lights to help make CG and live-action objects appear to be in the same environment.

reflection pass: In motion control photography is one of a set of passes that include the beauty pass, the matte pass, and the shadow pass. Its purpose is to capture only the light that is reflected on the subject. In the CGI world, it is a separate render output that retains only the reflections for use in compositing.

region of interest (ROI): A (usually rectangular) region that is determined by the user in order to limit certain calculations. See also domain of definition.

release print: A print of a movie that will be sent to theaters for display. A release print is several generations removed from the original negative.

render: The process of creating a synthetic image from a 3D data set.

render farm: A group of computers that is set up as a place to submit 2D or 3D processes for noninteractive computation.

render queue: The list of tasks waiting to be processed on a render farm.

RenderMan: Specialized rendering software offered by Pixar, Inc.

reposition: The process of adjusting the placement of an element within the frame. Also referred to as repo.

resampling: The process of reading previously sampled data for the purpose of converting or modifying it.

resolution: The amount of data that is used to capture an image. The term is typically used to refer specifically to the spatial resolution of a digital image. See also color resolution, temporal resolution.

resolution independence: The characteristic of a software package that allows the user to easily work with and move between an arbitrary number of different resolutions.

retinal disparity: (stereo) See disparity.

RGB: Red, green, and blue. The three primary colors or a method of specifying the colors in an image based on a mix of these three components.

RGBA: Red, green, blue, and alpha, grouped as a single unit.

ride film: A location-based entertainment that features a film whose camera movements are synchronized with some sort of moving seat or platform. Term was first coined by Douglas Trumbull.

rig: (stereo) Dual camera heads in a properly engineered mount used to shoot stereo movies.

ringing: A visual artifact, often caused by excessive sharpening, that is characterized by overemphasized transitions between bright and dark areas in an image.

RLA: Abbreviation for Run-Length Encoded Version A, a specific image file format. RLA is primarily used by the Wavefront Advanced Visualizer animation package to store output data and to exchange graphical data with other software applications. There are actually three variations of the RLA image file format.

ROI: Abbreviation for region of interest. Also used in the financial world as an abbreviation for return on investment, something your employer is probably worrying about right now.

rotation: A geometric transformation that changes the orientation of an image relative to a certain axis.

rotoscope: Originally the name of a device patented in 1917 by Max Fleischer to aid in cel animation. Now used as a general term for the process of creating imagery or mattes on a frame-by-frame basis by hand. Also referred to as a roto.

rotoscoped matte: A matte created via rotoscoping techniques.

rotoscoping: Also known as “Rotoing.” The process of hand drawing or tracing mattes around subjects. See rotoscope.

RP: Abbreviation for rear projection.

RTFM: Abbreviation for read the manual (sort of), a suggestion that is often given when someone asks a question instead of taking the time to look it up him- or herself.

run-length encoding: A lossless compression scheme that consolidates sequences of identical pixels into a single data representation.

run takes: In-progress versions of a shot, designated by specific numerical take numbers, to serve as a record of the shot’s progress at a particular point in its production history.

rushes: Another term for dailies, used primarily in Great Britain.

S

sampling: (1) The process of reading a signal at specific time increments. See also digitization. (2) The process of reading the color value from a pixel or a group of pixels.

saturation: The brilliance or purity of a given color. The difference between a pastel and a pure color is the amount of saturation.

scaling: A geometric transformation that changes the size of an image, usually without changing its location or orientation.

scan line: A single horizontal row of pixels in a digital image.

scanner: A device for digitizing film, print material, etc.

scene: (1) The image captured by a camera. (2) A collection of shots that share a common setting or theme.

scene-referred image: An image that has a direct, well-defined mapping between the colors in the image and the colors in the original scene.

scope: (1) Abbreviation for any anamorphic process, such as Cinemascope, Techniscope, Superscope. (2) Shorthand for video scope, a waveform monitor.

screen left: The left side of the screen or image from the viewpoint of the viewer. Opposite of screen right.

screen resolution: The number of horizontal and vertical pixels that a given display device is capable of showing. This should be independent of the resolution that the system is capable of processing.

screen right: The right side of the screen or image from the viewpoint of the viewer. Opposite of screen left.

screen space: (stereo) The region appearing to be within the screen or behind the surface of the screen. Images with positive parallax will appear to be in screen space. The boundary between screen and theater space is the plane of the screen and has zero parallax. See theater space.

script: A program written in a scripting language, including the language used by a compositing package to describe the set of image-processing operations to be applied to a set of images.

SDK: Abbreviation for software developer’s kit.

SECAM: Officially this is an acronym for séquentiel couleur à mémoire, but most English speakers use the translation sequential color and memory. SECAM is a standard for color television used in France and a few African and Eastern European nations. It carries 625 lines of resolution, played back at a rate of 25 frames per second.

seed: A number that is fed into a program or algorithm to produce a random number. The same seed will result in the same random numbers and therefore can provide for repeatable iterations.

selection device: (stereo) The hardware used to present the appropriate image to the appropriate eye and to block the unwanted image. For 3D movies the selection device is usually eyewear used in conjunction with a device at the projector, like a polarizing device.

self-illuminated blue screen: See transmission blue screen.

sequence: (1) A collection of images designed to be played sequentially. (2) A group of related scenes in a film, usually set in the same time and/or location.

server: A computer that is shared over a network by several users.

70mm film: The widest gauge film format, featuring twice the width of standard 35mm film. See also IMAX.

SFX: Often used as an abbreviation for special effects, although sound effects people will dispute this usage.

shadow pass: In motion control photography is one of a set of passes that include the beauty pass, the matte pass, and the reflection pass. Its purpose is to capture only the shadows cast by the subject. In the CGI world, it is a separate render output that retains only the shadow for use in compositing.

sharpening: The process of applying an algorithm that emphasizes the edges in an image. The result is an image that appears to have increased sharpness.

sharpness: The visual sense of the abruptness of an edge.

short lens: A relative term, in contrast to a long lens. Also known as a wide-angle lens.

shot: An unbroken continuous image sequence.

Showscan: A proprietary film capture/projection process that is characterized by a large-format negative and a playback speed of 60 frames per second. Pioneered by Douglas Trumbull.

shutter angle: The part of a motion picture camera that determines how long a given area of film will be exposed to a scene. Most cameras have the ability to adjust their shutter angle. A larger shutter angle will result in increased motion blur on moving objects.

shutter speed: The amount of time that a camera will spend capturing an individual image.

SIGGRAPH: The Special Interest Group for Graphics, a subgroup under the Association for Computing Machinery, and the major organization for graphics professionals. Also, the annual conference sponsored by this group, which features a large number of courses, seminars, and some really big parties.

silver halide crystals: The silver compounds, usually silver bromide and silver iodide, that are impregnated in the photographic emulsion of film. These compounds, when acted on by actinic rays, are disintegrated, with the formation of metallic silver in a finely divided state. The photographic image results when the film is subjected to processing. They are commonly seen as film grain.

sinc filter: A specific digital filter that is often used when resampling a digital image. The sinc filter is particularly well suited to transforming images into a lower resolution than they were originally.

16-bit image: In the visual effects world, this term typically refers to any image containing 16 bits of color information per channel.

16mm film: A film format with a gauge of 16mm that carries only two perforations along each frame and contains 40 frames per foot. Because the captured image area is significantly smaller than that of 35mm film, this film format is rarely used for visual effects work. However, 16mm is still occasionally used for documentaries and television commercials.

65mm film: A popular widescreen format that contains five perforations per frame (hence, the nickname five-perf ). The 65mm acquisition negative is usually printed onto 70mm film stock for release.

skinning: See texture mapping.

skip frames: A method of speeding up the motion of a sequence of images by removing selected (usually regularly spaced) frames. Also known as skip printing.

slate: Information about a particular shot that is placed at the head of the shot, before the actual image begins.

slop comp, slap comp: A very rough initial composite that is usually used to test or visualize basic element relationships.

slow motion: Any technique that is used to slow down the motion of objects in a scene. It may involve filming at a faster speed than the intended projection speed or it may involve some post-processing technique. Also referred to as slow-mo.

SLR: Abbreviation for single-lens reflex camera.

SMPTE: Abbreviation for Society of Motion Picture and Television Engineers.

snorkel lens: See periscope lens.

Sobel filter: A specific type of edge detection algorithm.

Sobel matte: A discrete differentiation operator, computing an approximation of the gradient of the image intensity function. In simplified words, it uses an edge detection algorithm to create an outline around the edge.

software developer’s kit (SDK): A programming interface that accompanies many software packages. It is used to write additional plug-ins and stand-alone programs to extend the capabilities of that software package.

solarization: An effect that is produced when a range of brightness within an image is inverted. Can be used to mimic an optical effect that occurs with extreme overexposure.

spatial aliasing: An artifact that is due to limited spatial resolution.

spatial convolution: See convolve.

spatial filter: A method of sampling and modifying the data in an image by looking at pixel groups.

spatial resolution: A measurement of the amount of data used to capture an image. In a digital image, spatial resolution is usually specified by giving the X and Y dimensions of the image as measured in pixels.

special effects: Term for on-set mechanical and in-camera optical effects that are created in front of the camera. Also known as practical or mechanical effects. The general public tends to use this term to encompass both practical effects and visual effects. Also referred to as SFX.

special visual effects: See visual effects.

spherical lens: A lens that does not change the apparent width-to-height relationship of the scene being photographed. This is in contrast to an anamorphic lens.

spill: Any light in a scene that strikes an object it was not intended to illuminate. See also blue spill, green spill.

spill suppression: Any process that removes or neutralizes undesirable spill from an object.

spline: A series of points connected by a line or curve. See spline curve.

spline curve: A continuous smooth curve defined by a certain number of control points. See spline.

splinter unit: A part of the production crew that is tasked with going off on their own to film or capture specific shots or plates.

split diopter: A split diopter is an auxiliary lens—half lens and half plain glass—that goes in front of the camera lens so only half of the scene is focused for close-ups.

split-screen: A basic composite in which two elements are combined using a simple matte with little or no articulation.

sprite: General term for a (usually small) 2D element that is animated within a larger scene. Often used in conjunction with a particle system.

square pixel: A pixel with equal X and Y dimensions.

squeezed image: An image that has been anamorphically compressed.

sRGB: A standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet.

stabilization: The process of removing bounce or jitter from a sequence of images.

staircasing: A spatial aliasing artifact in which a line or edge appears jagged, like the profile of a staircase, instead of smooth. Also called stairstepping.

stand-in: A reference object photographed in a particular scene that can later be used to help match the color and lighting of any new elements that will be added to that scene.

static image: An image that contains no motion.

static matte: Another term for a fixed matte.

steadiness: An image sequence in which the individual frames are stable relative to each other and do not suffer from any frame-to-frame jitter or bounce.

steady test: A test to determine if a camera or the imagery shot with that camera is steady.

stereo: (stereo) Short for stereoscopic. (If you are trying to learn about multichannel sound, you are in the wrong place.)

stereographer: The individual who is responsible for making sure all shots of a project are properly composed in terms of stereoscopic depth.

stereoplexing: (stereo) Short for stereoscopic multiplexing. A means of incorporating information for the left and right perspective views into a single information channel without expansion of the bandwidth.

stereopsis: (stereo) The binocular depth sense—literally, “solid seeing.”

stereoscope: (stereo) A device for viewing plano-stereoscopic images. It is usually an optical device with twin viewing systems.

stereoscopic image: Imagery that is designed to send a different image to each observer’s left and right eyes, thereby producing a sense of depth.

stereoscopic pair: A pair of images (one for each eye) that comprise a stereoscopic image.

stereoscopy: (stereo) The art and science of creating images with the depth sense stereopsis.

stochastic sampling: A random or semirandom sampling of a data set. Used for antialiasing, motion blur, etc.

stock: General term for motion picture film, or the specific manufacturer, manufacturer’s product code, or rating of that film.

stop: A way of measuring exposure that traces back to the different f-stop settings available on any given lens. The f-stops on a lens are calibrated so that each successive stop will give twice the exposure. Thus, “increase the brightness by one stop” means to double the brightness; “decrease by two stops” would result in one-fourth the original brightness.

stop-motion animation: An animation technique that involves photographing objects or characters a frame at a time, changing the pose or position of the object between each frame. The result, when played back at normal speed, is of a subject or object with motion or “life to it.”

storyboard: A sequence of drawings that shows the intended action in a scene. Used as a visualization tool before the scene is shot.

strobing: A rhythmic flicker in a moving image. Often due to a lack of motion blur when dealing with synthetic images.

subpixel: Any technique that works at a resolution of greater than a single pixel; usually accomplished by making slight weighted corrections to several surrounding pixels.

super: Shortened form of superimpose.

Super 8mm film: The Super 8 format is a narrow-gauge film that contains one perforation along each side and runs 72 frames per foot.

Super 16mm film: A 16mm film that uses an image area that extends beyond the sound track of normal 16mm film. It is a single-perforation film that extends the image area out to where the second row of perforations would normally be. Also called single-perf.

Super 35mm film: The Super 35 format is a 35mm film that uses the full aperture of the negative to capture its images. Super 35 can be used for a number of different formats that use full-aperture framing, but it is most commonly used for films that are intended to be projected with a 2.35:1 aspect ratio. Also referred to as Super Techniscope, Super 1.85, or Super 2.35.

Super Techniscope: Another name for Super 35.

superblack: Any brightness level that drops below the normal representation of black for a given image or device. In video, superblack levels may be used for keying.

superimpose: To place one image on top of another, usually with some transparency involved.

Superscope: An early anamorphic format that uses the full width of the 35mm film area and is cropped top and bottom for a 2:1 aspect ratio during projection. See also Cinemascope, Techniscope.

superwhite: Any brightness level that rises above the normal representation of white for a given image or device.

surface normal: A vector that is perpendicular to a surface at a specific point on the surface. In compositing, multiple-pass rendering will often include a surface-normal pass.

surround: (stereo) The vertical and horizontal edges immediately adjacent to the screen.

sync block: A mechanical device used to measure film length. Film is loaded onto a cylinder calibrated at 1 foot per rotation. An attached counter reads and updates the total amount of footage that winds through.

T

“T”: (stereo) In stereoscopy, “T” is used to denote the distance between the eyes, called the interpupillary or interocular distance; “T” is used to denote the distance between stereoscopic camera heads’ lens axes and is called the interaxial.

tablet: A user-input device that provides a greater amount of control than the traditional computer mouse. Generally used in conjunction with a special pen.

tail slate: Slate information that is recorded at the end of the shot instead of the beginning. Generally only used in live-action photography; the slate information is filmed upside-down, to distinguish it from a normal slate.

take: When a particular shot is photographed multiple times in order to achieve a desired result, each time is referred to as a take. This concept extends to digital compositing, where each test that is sent to film or video is usually kept track of with a take number.

TARGA: A specific image file format.

Technical Assistant (TA): An individual who is responsible for much of the basic data wrangling within a facility; often handles file backups. (See the list of VES-approved titles in Appendix B.)

Technical Director (TD): An individual responsible for ensuring that the technical aspects of a digital shot are addressed. Generally considered to be a subset of digital artist with particular technical skills. (See the list of VES-approved titles in Appendix B.)

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. Also see previs, pitchvis, on-set previs, and postvis.

Techniscope: A system designed to produce 35mm anamorphic prints from 35mm negatives using an image area that is approximately half the height of regular 35mm images and a special camera. The negative image area is then stretched to normal height and projected at an aspect ratio of 2.35:1. See also Cinemascope, Superscope.

telecine: A device for rapidly converting motion picture film into a video format. A telecine device is much faster than a film scanner but will produce lower quality results.

telephoto lens: Any lens that has a longer-than-normal focal length. For a 35mm camera, a focal length of 50mm is considered normal, since it reasonably duplicates the magnification of a human eye.

temp comp: Shortened form of temporary composite.

temporal: Relating to time or something that changes over time.

temporal aliasing: An artifact that is due to limited temporal resolution.

temporal filling: Process by which missing image data is replaced from frames elsewhere in a shot where that image area is revealed.

temporal resolution: A measurement of the amount of data used to capture a sequence of images. Temporal resolution is usually specified by giving the number of frames per second used to capture the sequence.

temporary composite: A rough composite produced for a number of different reasons, usually to better judge the spatial and color relationships of the elements in a scene so that they can be modified to produce a final composite. Also called a temp comp.

10-bit image: In the visual effects world, this term typically refers to any image containing 10 bits of color information per channel. The most widely used 10-bit image format used in visual effects work is the Cineon file format.

tessellation: A collection of plane figures that fills the plane with no overlaps and no gaps. One may also speak of tessellations of the parts of a plane or of other surfaces. Generalizations to higher dimensions are also possible. Tessellations frequently appeared in the art of M. C. Escher. Tessellations are seen throughout art history, from ancient architecture to modern art. Also referred to as tiling of the plane.

texture mapping: Process in which an image is overlaid onto a CG object.

TGA: See TARGA.

theater space: (stereo) The region appearing to be in front of the screen or out into the audience. Can also be called audience space. Images with negative parallax will appear to be in theater space. The boundary between screen and theater space is the plane of the screen and has zero parallax. See screen space.

35mm film: The most common film format used in professional moviemaking. Each frame contains a gauge of 35mm and four perforations (thus its nickname four-perf) and there are 16 frames per foot. The sound information usually runs along the left side of the film between the perforations and the image.

32-bit image: In the visual effects world, this term typically refers to any image containing 32 bits of color information per channel. At this bit depth the channels are usually stored with a floating point data representation; hence, a 32 bit-per-channel image is thus also referred to as a float image.

3:2 pulldown: Usually synonymous with 2:3 pulldown.

3:2 pullup: Usually synonymous with 2:3 pullup.

3D: Shorthand for three dimensional. Having characteristics in three different dimensions, most often width, height, and depth.

3D film: (1) A general term referring to a film created entirely with 3D computer graphics. (2) Often used as another term for a stereoscopic film.

3D glasses: Specially designed glasses that are worn to view stereoscopic imagery. See also anaglyph glasses, flicker glasses, polarized glasses.

3D graphics: Computer graphics that involves the creation of three-dimensional models within the computer.

3D motion blur: Motion blur that is calculated for a CG scene as it is rendered, as opposed to applying 2D motion blur as a postprocess.

3D tracking: Unlike 2D tracking, 3D tracking is intended to recreate the full 3D movement of the camera that photographed a particular scene (or, less commonly, the full 3D movement of an object in the scene). See also matchmove.

three-perf: A technique used to maximize the use of raw film stock in 1.85 formats so that almost no film is wasted. Most cameras use a four-perf pulldown that creates a lot of unused film between the captured images, whereas a three-perf pulldown positions the captured images closer together.

TIFF: Abbreviation for tagged image file format, a specific image file format.

time code: An electronic indexing method used with videotapes. Time code is measured in hours, minutes, seconds, and frames.

timeline graph: A graph that represents the temporal relationships between objects or data.

timing: (1) A general term referring to how a particular event or object moves or evolves over a period of time. (2) See color timing.

tracking: The process of determining the movement of objects in a scene (relative to the camera) by analyzing the captured footage of that scene. See 2D tracking, 3D tracking.

tracking markers: Another term for witness points.

transformation: Usually refers to a geometric transformation.

transition effect: A method for moving from one scene to the next. See also wipe, dissolve.

translation: A geometric transformation that refers only to a change in position, without a change in scale or rotation.

translucent: A term that refers to something that is partially transparent; usually implies some additional image distortion, such as blurring.

transmission blue screen: A blue screen that has a series of lights behind the translucent blue screen that would illuminate evenly. They are very easy to use but due to their design they are not very flexible or portable.

transparent: The characteristic of an image that allows other images that are behind it to still be partially visible. Transparent is the opposite of opaque.

traveling matte: Any matte that changes over time, as opposed to a static matte.

trucking: Camera movement that is perpendicular to the direction of the camera lens.

t-stop: A measurement of the aperture of a lens that also takes into account the amount of light lost when passing through the lens elements themselves.

tumble paint: A term of art used to distinguish 3D paint systems that allow direct painting on the mesh, such as Mudbox or Zbrush, as differentiated from systems that use projection cameras to place textures on a model.

turnover: The process of handing over a visual effects shot or edited and locked visual effects sequence to a visual effects facility to begin work.

24p: Video that is shot at 24 frames per second.

2D: Shorthand for two dimensional. Containing information in only two dimensions (generally width and height) without any sense of depth.

2D graphics: Computer graphics that does not use any 3D information and thus involves no explicit depth information.

2D motion blur: Motion blur that is added as a post-process to moving objects in an image.

2D tracking: The process of determining the motion of objects in a scene relative to the camera. The data derived by a 2D track is dependent on the number of points tracked. See 3D tracking, one-point track, two-point track, four-point track.

2k resolution: A general term referring to any digital image containing an X resolution of approximately 2048 pixels. The actual dimensions of a 2k image depend on the aspect ratio of the imagery. A common 2k resolution used in visual effects when working with full aperture framing is 2048 × 1556.

two-perf: Nickname for 16mm film because it carries only two perforations for each frame.

two-point track: A type of 2D tracking in which two points are selected from a sequence of images to extract an approximation of an object’s movement relative to the camera. Allows for the determination of rotation and scale as well as basic translation. See one-point track, four-point track.

2.35 format: Pronounced “two-three-five format,” 2.35 is a widely used aspect ratio for film. It can also be written as 2.35:1, which means that the image is 2.35 times as wide as it is high. Cinemascope and Super 35 are most commonly used as the acquisition format to acquire this widescreen format.

2.5D (2 1/2 D): Pronounced “two-and-a-half D,” this is a general term for techniques that use 2D imagery in a 3D environment to give the illusion of a true 3D scene.

2:3 pulldown: Pronounced “two-three pulldown,” this is a method for converting 24-fps film to 30-fps video. Also called a 3:2 pulldown or just pulldown.

2:3 pullup: Pronounced as “two-three pullup,” this is a method for converting 30-fps video to 24-fps film. Also called a 3:2 pullup or just pullup.

U

Ultimatte: A proprietary tool based on the color difference method that can be used to extract a matte from an image shot in front of a uniform backing.

undercrank: Running a camera at a lower speed than the intended projection rate, resulting in projected footage that appears to move faster than normal. Footage shot at a slower-than-normal rate is said to have been shot undercranked.

underscan: The adjustment on a video monitor that increases the viewable height and width of the image area so that the edges of the display can be seen.

unpremultiplied image: An image whose red, green, and blue channels have not been multiplied by an alpha channel. Opposite of premultiplied image.

unpremultiply: To redivide the RGB channels of an image by its own alpha channel. See unpremultiplied image.

unsharp masking: A particular technique used to sharpen an image that involves subtracting a slightly blurred image from the original. Used not only in the digital realm but also as a photographic technique.

user interface: The portion of a computer program that deals specifically with how the user interacts with the software. See also graphical user interface.

V

value: In the HSV color space, the value equals the maximum of the red, green, and blue components.

vaporware: A product that does not yet exist but is nevertheless being promised for delivery.

vector graphics: Geometrical primitives, such as points, lines, curves, and shapes or polygon(s), that are based on mathematical equations that represent images in computer graphics. Unlike raster graphics, which is made up of a grid of pixels, vectors are usually just lines drawn on a screen.

vectorscope: A device used to view the chrominance portion of a video signal. Radial distance from the center of the display represents saturation (chrominance amplitude), and the counterclockwise or clockwise angular distance represents the hue (chrominance phase). See also waveform monitor.

VFX: Abbreviation for visual effects.

view frustum culling: The process of removing objects that lie completely outside the viewing frustum from the rendering process.

viewing frustum: The region of space in the modeled world that may appear on the screen; it is the field of view of the notional camera. The exact shape of this region varies depending on what kind of camera lens is being simulated, but typically it is a frustum of a rectangular pyramid (hence the name). The planes that cut the frustum perpendicular to the viewing direction are called the near plane and the far plane. Objects closer to the camera than the near plane or beyond the far plane are not drawn. Often, the far plane is placed infinitely far away from the camera so all objects within the frustum are drawn regardless of their distance from the camera. Also referred to as a view frustum.

vignetting: A camera or lens artifact characterized by a darkening of the image in the corners of the frame.

virtual asset: Database definition of asset that is not actually a file on disk.

visible spectrum: The range of colors between ultraviolet and infrared that is visible to the human eye.

VistaVision: A specialized 35mm film format that runs the film through the camera horizontally instead of vertically and is able to capture more than twice the resolution of a standard 35mm frame. Generally only used for visual effects work nowadays. Also known as eight-perf and also spelled Vistavision.

visual effects (VFX): A broad term that refers to just about anything that cannot be captured using standard photographic techniques. Visual effects can be accomplished in camera or via a number of different optical or digital post-production processes. Visual effects are a subcategory of special effects.

Visual Effects Director of Photography: The individual responsible for photographing any elements that will be used in visual effects production. (See the list of VES-approved titles in Appendix B.)

Visual Effects Producer: The individual responsible for the administrative side of visual effects production. (See the list of VES-approved titles in Appendix B.)

Visual Effects Supervisor: The individual responsible for the creative and technical side of visual effects production. (See the list of VES-approved titles in Appendix B.)

Volume: Term used to describe the motion capture stage. However, unlike stage, it implies a 3D space.

W

wagon wheeling: An image artifact caused when a rotating object (such as a wheel) appears to be moving at the wrong speed or in the wrong direction relative to the object to which it is attached. This is a temporal aliasing artifact.

Waldo: A mechanical input device that has encoders attached to its axes of motion such that any motion of the device will translate to a series of numbers that are read by a computer as locations or rotations in 3D space. Such devices are used to assist in animation of characters, motion-controlled rigs, etc. Named after the Robert A. Heinlein short story Waldo.

warm: A nonexact term used to describe an image that is biased toward the red portion of the spectrum.

warping: A geometric, per-pixel distortion of an image, often based on some kind of spline- or grid-based control.

warping engine: Within a package used for compositing, the code that is responsible for any geometric transformations.

waveform monitor: A device primarily used to measure the luminance of a video signal with respect to time. Also called a scope. See also vectorscope.

wavelet: A method of representing an image based on frequency information. Used as the basis for certain compression techniques.

weave: See film weave.

wedge: See color wedge, exposure wedge.

white balance: The calibration of a camera for accurate color capture or of an image for accurate color display based on specific lighting conditions.

white point: (1) On a piece of film, the measured density in the area of least opacity. (2) In a digital image, the numerical value that corresponds to the brightest area that will be represented when the image is eventually viewed in its final form.

wide-angle lens: Any lens that has a smaller-than-normal focal length. For a 35mm camera, a focal length of 50mm is considered normal, since it reasonably duplicates the magnification of a human eye.

widescreen: A generic term that usually refers to any image with an aspect ratio greater than 1.33:1.

window: (stereo) The stereo window that corresponds to the screen surround unless floating windows are used.

wipe: A specific transition effect in which one scene is horizontally or vertically revealed to replace another scene.

wire removal: A generic term for the process of using digital painting or compositing techniques to remove undesirable wires, rigs, or harnesses that were needed to aid certain stunts or practical effects.

witness camera: Cameras used to film or videotape the action from one or more viewpoints that are not the same viewpoints used by the primary production camera. This data is used in the creation of many things, ranging from determining where everything on the set was in three dimensions to providing animation reference.

witness points: Specific objects placed into a scene that can later be analyzed to determine the movement and configuration of the camera that photographed the shot using tracking techniques. Also known as tracking markers.

working resolution: The resolution of the images that will be produced by any given compositing process.

X

x: An abbreviation used to denote a frame. For example, “24x” denotes 24 frames.

x-axis: Generally the horizontal axis.

Y

y-axis: Generally the vertical axis.

Y-depth image: A specialized image that uses the brightness of each pixel to specify the height of that pixel relative to some reference ground plane. See also Z-depth image.

YIQ: A color space used for NTSC television, in which the brightness (Y), orange-cyan (I), and green-magenta (Q) components are encoded together.

YUV: A color space in which Y represents the luminance and U and V represent the chrominance of an image or video.

Z

z-axis: The axis perpendicular to the x-axis and the y-axis, and consequently the axis that is used to represent depth.

Z-buffer: Another term for a Z-depth image.

Z-channel: A Z-depth image that is integrated with a color image as an additional channel.

Z-depth compositing: Compositing images together with the use of a Z-buffer to determine their relative depths or distances from the camera.

Z-depth image: A specialized image that uses the brightness of each pixel to specify the relative depth for each pixel in the corresponding RGB image. This depth may be measured relative to some arbitrary fixed point in space or relative to the virtual camera that is being used to capture the scene. Also called a Z-buffer.

zoom: (1) In a real camera, the act of increasing the focal length of the camera’s lens to magnify a portion of the scene. (2) With digital images, the act of increasing the scale of a portion of an image in order to duplicate the effect of a camera zoom.

ZPS: (stereo) Abbreviation for zero parallax setting, which is the means used to control screen parallax to place an object in the plane of the screen. ZPS may be controlled by HIT, or toe-in. Refer to the plane of zero parallax or the point of zero parallax (PZP) so achieved. Prior terminology says that left and right images are converged when in the plane of the screen. That term should be avoided because it may be confused with the convergence of the eyes and because the word implies rotation of camera heads. Such rotation produces geometric distortion and may be expedient in camera rigs, but it is unforgivable in a CG virtual camera rig.

Z-space: A way of stating where an object is in relation to the camera on one axis—close to near.