CHAPTER 1 AL Introduction to Computer Graphics and 3D RI This book is to introduce you to the workings of 3D animation (called computer GH TE D MA TE graphics, or CG) with one of the most popular programs on the market, Autodesk’s Maya. It will introduce you to a lot of the features and capabilities with the hopes of energizing you to further study.
■ chapter 1: Introduction to Computer Graphics and 3D Embrace the Art Art, in many instances, requires transcendence of its medium; it speaks of its own accord. Learning to look past what you’re working with and seeing what you’re working for is key to learning CG art. So don’t view this as learning a software package but as learning a way of working. As you begin learning 3D with Maya, you acquire a new language, a new communication.
computer graphics If you’re familiar with 2D graphics software such as Adobe Illustrator or Macromedia Flash, you already know something about vectors. What Maya and other 3D graphics tools add are calculations of depth. Instead of being drawn on a flat plane, objects are defined in three-dimensional space. This makes the artist’s job fairly cerebral and very different than it is with 2D art; there is more of a cross chat between the left and right sides of the brain.
■ chapter 1: Introduction to Computer Graphics and 3D Fairly soon, you will begin to see CG as a bigger part of the everyday computing environment, as we are seeing with image editors and digital-video editing software now. The more familiar you are with it, whether with Autodesk Maya or another package, the greater your part in the computing future. The day will soon be on us when we can custom-make our own environments for our 3D Windows desktops.
the stages of production Since the CG artist must define 3D scenes in the program, it is essential to have a succinct plan of attack for a well-organized production. The more time spent planning and organizing for CG, the better. Entering into production without a good plan of attack is not only going to cause you trouble, it will stunt the growth of your project. In the real world, preproduction is part of every CG animation project.
■ chapter 1: Introduction to Computer Graphics and 3D CG production itself has an involved number of steps that are usually defined by the needs of the production. We’ll peer into 3D work flow in the next section, but to make a long story short, 3D scenes are created, lit, and animated in the production phase. Most of the CG techniques you’ll learn in this book are part of the production phase.
the stages of production One of the biggest problems students new to the CG process have is their need to generate their scene in one fell swoop. It is important to realize the component nature of CG and how you can use that to your advantage in rendering items separately and compositing them together in the finishing stage. Editing The rendered and composited CG footage is collected and edited together to conform to the script and boards. Some scenes are cut or moved around to heighten the story.
■ chapter 1: Introduction to Computer Graphics and 3D How It All Works Together The process behind making a South Park episode makes for a perfect pipeline example. Although the show appears to be animated using paper cutouts, as was the original Christmas short, the actual production work is now done using Maya. In preproduction on a typical episode, the writers hammer out the script, and the voice talent records all the voices before the art department creates the visuals for the show.
the cg production work flow It helps a great deal in figuring out how to proceed with the modeling to have a good idea of your whole story via a storyboard. Knowing how an object is used in a scene gives you its criteria for modeling. You never want to spend more time on a model than needed. Beginning with a highly detailed model for a far-away shot will waste your time and expand rendering times.
■ chapter 1: Introduction to Computer Graphics and 3D You should not create incredibly detailed environments if they are not featured in a shot, especially environments that use a lot of geometry. The greater the amount of geometry, the slower your computer will run and the longer rendering will take. You can create a good deal of the environment using clever textures on simple geometry. Detailed maps on bare surfaces are used frequently for game environments.
the cg production work flow To animate something properly, though, you might need quite a lot of setup beyond just modeling. Depending on the kind of animating you’ll be doing, you might need to set up the models for however you’ll be animating them. For example, for character animation you will need to create and attach an armature, or skeleton, to manipulate to make the character move, like a puppet, and do your bidding.
■ chapter 1: Introduction to Computer Graphics and 3D time or budgetary constraints, you want simple scenes to keep the render resources and times to a minimum. But the general rule in production is, you’re always out of time, so the most efficient pipeline will be your savior, and eventually your producer or boss will tire of hearing, “But I’m still rendering.” As you learn, use as many lights and as much geometry as you can handle for your scenes.
core concepts raster images, you need to use a higher resolution to begin with. The higher the resolution, the larger the file size. Figure 1.1 shows what happens when you blow up a raster image. In light of this limitation, you might wonder why raster images are used. The answer lies in how these images are generated. Most common raster displays are television or computer screens. In fact, the term raster originally referred to the display area of a television or computer monitor.
■ chapter 1: Introduction to Computer Graphics and 3D Figure 1.2 A vector image at its original size (left) and blown up to 200 percent (right) When scaled, vector graphics do not suffer from the same limitations as raster images. As you can see in Figure 1.2, vectors can be scaled with no loss of quality; they will never pixelate.
core concepts 8-Bit Image File Commonly referred to as 24-bit color display or True Color, each color channel is given 8 bits for a range of 256 shades of each red, green, and blue channel for a total of 16 million colors in the image. This color depth gives the best color quality for an image and is widely used in most animation applications. It is said that the human eye cannot see quite as many shades of color as there are in a True Color image.
■ chapter 1: Introduction to Computer Graphics and 3D MOVIE FILES Animations can also be output to movie files such as AVI or QuickTime. These usually large files are self-contained and hold all the images necessary for the animation that they play back as frames. Like image files, movie files can be compressed to keep their sizes to a minimum, but they suffer from quality loss as well.
core concepts With subtractive color mixing for painting, the traditional color wheel’s primary colors are red, blue, and green. These three pigments can be mixed together to form any other color pigment. This is the basis for the color wheel most people are exposed to in art education.
■ chapter 1: Introduction to Computer Graphics and 3D All output from a computer, which is RGB based, to a printer goes through a CMYK conversion as it’s printed. For professional print work, specially calibrated monitors are used to better preview the CMYK color of an RGB image before it is printed. Fortunately, only the print professionals need to worry about this conversion process because most of it is handled by our graphics software to a fairly accurate degree.
core concepts Any discussion of resolution must include the matter of aspect ratio. Aspect ratio is the ratio of the screen’s width to its height, and of course, there are standards: Academy Standard 1.33:1 or 4:3 The most common aspect ratio. The width is 1.33 times the length of the height. This is the NTSC (National Television Standards Committee) television aspect ratio as well as the aspect ratio of 16 mm films and some 35 mm films, especially classics such as Gone with the Wind. Widescreen (a.k.a.
■ chapter 1: Introduction to Computer Graphics and 3D Space is defined in three axes—X, Y, and Z—representing width, height, and depth. The three axes form a numeric grid in which a particular point is defined by its coordinates set forth as (#,#,#) corresponding to (X,Y,Z). At the zero point of these axes is the origin. This is at (0,0,0) and is the intersection of all three axes. The 3D space defined by these three axes is called the World Axis, in which the XYZ axes are a fixed reference.
core concepts Form, Space, and Composition Space is defined as your canvas or frame. Since ultimately your canvas will be a rendered image, your design space becomes your image frame. Whether that frame falls into a tiny web window or a huge IMAX screen, the basics of design always apply: how you arrange your forms and divide your space says a lot. A form in design is anything that can be seen; it has some sort of shape, color, or texture that distinguishes it from its frame.
■ chapter 1: Introduction to Computer Graphics and 3D Contrast Contrast in design describes how much your foreground subject “pops” from the background. As you can see in Figure 1.5, when you create an area in your frame that contains little variation in color and light, the image will seem flat and uneventful. Using dark shadows and light highlights increases the perceived depth in the image and helps pop out the subject from the background.
basic film concepts Color Your use of color also plays a big part in creating impact in your frame. Warm colors tend to come out toward you, and cooler colors recede into the frame. Placing a warm color on a subject on a cool background creates a nice color contrast to help the dynamics of your frame. Colors opposing each other on the color wheel are complementary colors and usually clash when put together. Using complementary colors can create a wide variation of contrast in your scene.
■ chapter 1: Introduction to Computer Graphics and 3D CG productions of even the simplest topics can follow this simple organization. By following a similar layout in the scripting and storyboarding of your own short, you will find the entire production process will become easier and the effect of your film stronger. Lighting Without lights, you can’t capture anything on film. How you light your scene affects the contrast of the frame as well as the color balance and your overall design impact.
basic film concepts ■ 25 In CG, a keyframe can be set on almost any aspect of an object—its color, position, size, and so on. Maya will interpolate the in-between frames between the keyframes set by the animator. In reality, you can set several keyframes on any one frame in CG animation. Figure 1.6 illustrates a keyframe sequence in Maya. Figure 1.6 Keyframe at frame 1 Frame 5 Frame 10 Frame 15 Frame 20 Frame 25 Keyframe at frame 30 Keyframing.
■ chapter 1: Introduction to Computer Graphics and 3D Weight Weight is an implied facet of design and animation. The weight of your subject in the frame rests on how it is colored and its contrast, shape, and location in the frame and the negative space around it. In animation, the idea of weight takes on a more important role. How you show an object’s weight in motion greatly affects its believability.
basic film concepts SUGGESTED READING The more you know about all the arts that inform CG, the more confident you’ll feel among your peers. To get started, check out the following excellent resources. ART AND DESIGN These books provide valuable insights into the mechanics and art of design. The more you understand design theory, the stronger your art. Bowers, John. Introduction to Two-Dimensional Design: Understanding Form and Function. New York: John Wiley & Sons, 1999. Itten, Johannes.
■ chapter 1: Introduction to Computer Graphics and 3D Physics You’ll see in Chapter 12 that one of Maya’s most powerful features is its ability to simulate the dynamics of moving objects. To use that capability effectively, you need a general awareness of the properties of physics—how objects behave in the physical world. NEWTON’S LAWS OF MOTION There are three basic laws of motion.
summary Now that you have a foundation in CG and 3D terminology and core concepts, you are ready to tackle the software itself. Maya is a capable, intricate program. The more you understand how you work artistically, the better use you will make of this exceptional tool. It seems as if there is a lot to think about before putting objects into a scene and rendering them out. With practice and some design tinkering, though, all this becomes intuitive to the artist.