Even thought the prerequisites for Introduction to Computer Graphics said, “A basic understanding of computers and algebra,” I went anyway. While I understand computers fairly well, from a user standpoint, I was a math geek in that I could barely understand the word questions much less put them into usable equations.
The section of the course I was most interested in was called “Rendering.” Everywhere you went at SIGGRAPH there was talk of rendering images and the big daddy of rendering software, Renderman. The course lecturer was Andrew Glassner, who was listed only as a consultant in my program, and he was a great speaker, excited about his subject in a way that made you want to understand what he was saying. Once again the room was filled with state of the art monitors that allowed us to follow along with the computer program the lecturer was using without getting a neck crick. The premise he used to lead us through the rendering process was that we wanted to make an animated fly for a movie.
It turns out that a terrible fact was revealed to me right at the beginning of the course: graphics are math. Excuse me if I sound simple minded and stunned. It makes sense of course. If the words I am typing are really “1” and “0”, then the amazing dinosaurs in DINOSAUR can be mathematical equations. The body and legs of our fly were nothing but cylinders twisted and bent to make the deformed legs of the world’s most famous house pest. This is over simplifying the amount of work that went into creating software that will design cylinders that you can shape into fly legs, but that is the basic premise. The bodies of animated characters are polygons and such, all manipulated to form very complex mathematical equations that equal dinosaur, or Mickey Mouse in digital.
The Rendering Equation, according to Mr. Glassner, unifies all algorithms. What that means exactly, I’m not sure. Once he mentioned that it was related to nuclear physics, I stopped thinking clearly. However, for those truly dedicated to finding out, there is a 1986 SIGGRAPH paper on the subject that can be located by contacting SIGGRAPH at their web site.
He went on to explain, in more friendly, English major like terms, that rendering was turning ideas into pictures as well as a communications tool, in short, it was a means to an end. Very few people wrote their own rendering software, and in this class, we were going to follow in their footsteps using the popular Renderman software. Glassner considered computer graphics to be an emerging visual art form that just had a different pallet of materials to work from. I decided to think of it as very flat instillation art.
Creating a CG image is literally creating an “image” for the eye to see, and seeing is all about light. The light source, sun or man made, fluorescent or halogen, the things about seeing that most people don’t really notice, all must be taken into consideration when creating a CG image if you want it to mimic reality successfully. Light also influences the color and contrast of images as they move.
Our fly for example looked like a flat cartoon until we gave the computer program a light source and angle and the light began to interact with the fly’s surface creating shadows and color variations. Images are basically an outline that forms a shape combined with shading that defines that shape, but of course we spend most of our time wondering about the thing that the shape makes. Whether it is a car we want to buy, a person we want to date or which dress to wear, we think about an object’s relationship to us and not the physics that went into making its shape. Computer graphics, on the other hand, consider little else.
Rendering is the process of putting together the mathematical shapes of light, shadow and texture to form an image. Once all of these were put together in our example, we had a fly that was more than a cartoon and less than reality. Of course software designers are working on the “less than reality” problem even as I type. Several examples were shown of inanimate objects and man made landscapes and architecture, which looked amazingly real. Using digital photos the designers can teach the computer what different types of light does inside a given space and around the geometry of various objects. One example, of the interior room of a “House Beautiful” style house full of natural light, was so convincing that I thought it was the “real” example that would be used against the digital example.
The hardest objects to simulate digitally and teach the computer about are, of course living forms, mostly humans. Perhaps it is because humans see themselves as the most real of objects and are particularly harsh when critiquing images based on their own kind. Maybe a real fly would not have thought much of our CG attempt, but would have been happy to buzz the ear of one of our CG humans. Who knows? I just wish I had paid more attention in that pesky algebra class.