CG and CGI are the abbreviations for computer graphics and computer graphics imagery, respectively, and are often used interchangeably. CG literally refers to any picture or series of pictures that is generated by an artist on a computer. However, the industry convention is to use the terms CG and CGI to refer to 3D graphics and not to images created using 2D image or paint programs such as Photoshop.
Most 2D graphics software is bitmap based, whereas all 3D software is vector based. Bitmap-based software creates an image as a mosaic of pixels, filled in one at a time. Vector-based software creates an image as a series of mathematical instructions from one calculated, or graphed, point to another. This much more powerful method for creating graphics is behind all the impressive CG images you’ve seen in movies, videogames, and so on. It’s also the method for the images you’ll soon create with Maya. You’ll learn more about vectors and bitmaps in the section “Computer Graphics Concepts” later in this chapter.
If you’re familiar with 2D graphics software, such as Adobe Illustrator or Adobe Flash, you already know something about vectors. Maya and other 3D graphics tools add the calculation of depth. Instead of drawing objects on a flat plane, they’re defined in three-dimensional space. This makes the artist’s job fairly cerebral and very different than it is for 2D art; in 3D art, there is more of a dialogue between the left and right sides of the brain. When working with 3D graphics tools, you get a better sense of manipulating and working with objects, as opposed to dealing with the lines, shapes, and colors used to create 2D images.
A Preview of the 3D Process
The process of creating in 3D requires that you either model or arrange prebuilt objects in a scene, give them color and light, and render them through a virtual camera to make an image. In essence, you create a scene that tells the computer what objects are in the scene, where the objects are located, what the colors and textures of the objects are, what lighting is available, and which camera to use in the scene. It’s a lot like directing a live-action production, but without any actor tantrums.
A large community on the Web provides free and for-pay models that you can use in your scenes. Sites such as www.turbosquid.com and www.archive3d.net can cut out a lot of the time you might spend creating all the models for a CG scene. This gives you the chance to skip at least some of the modeling process, if that isn’t your thing.
With CG, you work in 3D space—an open area in which you define your objects, set their colors and textures, and position lights as if you were setting up for a live photo shoot. CG is remarkably analogous to the art and practice of photography and filmmaking.
Photographers lay out a scene by placing the subjects into the frame of the photo. They light the area for a specific mood, account for the film qualities in use, adjust the lens aperture, and fine-tune for the colors of the scene. They choose the camera, film, and lens based on their desired result. Then, they snap the pictures and digitally transfer them or develop them to paper. Through this process, a photo is born.
After you build your scene in 3D using models, lights, and a camera, the computer renders the scene, converting it to a 2D image. Through setup and rendering, CGI is born—and, with a little luck, a CG artist is also born.
Rendering is the process of calculating lights and shadows, the placement of textures and colors on models, the movement of animated objects, and so on to produce a sequence of 2D pictures that effectively “shoot” your virtual scene. Instead of an envelope of 4 × 6 glossy prints, you get a sequence of 2D computer images (or a QuickTime or AVI [Audio Video Interleave] movie file) that sit on your hard drive waiting to be seen, and invariably commented on, by your know-it-all friends.
In a nutshell, that is the CG process. You’ll need to practice planning and patience, because CG follows conventions that are different from those for painting programs and image editors. The CG workflow is based on building, arrangements, and relationships. But it’s an easy workflow to pick up and master in time. It can be learned by anyone with the desire and the patience to give it a try.
Animation
Animation is change over time. In other words, animation is the simulation of an object changing over a period of time, whether it’s that object’s position or size, or even color or shape. In addition to working in the three dimensions of space, Maya animators work with a fourth dimension: time.
All animation, from paper flipbooks to film to Maya, is based on the principle that when we see a series of rapidly changing images, we perceive the changing of the image to be in continuous motion. If you have a chance to pause and step through an animated film, frame by frame, on your DVD player or DVR, you’ll see how animation comes together, literally step by step.
To create CG animation yourself, you have to create scene files with objects that exhibit some sort of change, whether through movement, color shift, growth, or other behavior. But just as with flipbooks and film animation, the change you’re animating occurs between static images, called frames, a term carried over from film. You define the object’s animation using a timeline measured in these single frames.
You’ll learn more in the section “Basic Animation Concepts” later in this chapter. For now, let’s move on to the stages of CG production.