Computer-Generated_Art

Although there's still some argument about whether computers should have anything to do with Art (with the capital "A"), there's a lot less of it now than there ever has been. However, the argument has died down a lot with the avalanche of sheer _content_ from Hollywood and Uncle Joe's basement.

This wasn't always the case. In the beginning serious people asked serious questions like "can computers appreciate beauty?" and the like. The emerging answer seems to be that it makes a great paintbrush. A paintbrush makes no commentary about the quality of the work, but in the hands of a master can demonstrate the subtlest shadings and evoke the strongest emotions. The computer is a tool, and a liberating one. Your standard paintbrush also doesn't have an undo.

The first people to use a computer to generate images generally weren't interested in artistic effect. They just wanted something easier to interpret than a printout full of numbers or stacks of punch cards. In fact the, the first radiosity rendering (radiosity is a special technique that computes the "energy" of light in a given scene) was not actually rendered by computer. A computer calculated a set of grey values for the surfaces of objects in a scene and a human artist cut and ironed special paper together to create the scene based on the computer's calculations. [MASSON 389]

Now, thanks to the motion picture and advertising industries, computer generated imagery (CGI) is usually used to augment reality (as in adding dinosaurs) or to extol the advantages of a particular product. Any artistic merit in these is due to the hard work and late nights of the animators and production crew, and usually only tolerated by management as long as it doesn't get in the way of pushing the product. [That sounds a bit biased, which may not be proper for an encyclopedia, even an "informal" one... Been in too long, I guess.]

However, thanks to an influx of cheap tools for cheap personal computers art may have its chance again. Compared to the price of oils and easel and canvases, a PC and the occasional trip to the copy shop looks almost thrifty. And just like the paintbrush, the computer won't make snarky remarks about the quality of your work.

So, discarding your paintbrush (undo button still infuriatingly absent), you want to perpetrate Art (note initial capital) with the help of a computer. What's it all about then? [Note: shouldn't read Register while typing.]

Right now, there are two main paradigms in computer generated imagery. The simplest is 2D and directly maps to how you might draw an image on a piece of paper with a pencil. In this case, however, the image is on the computer screen and the instrument you draw with might be a tablet stylus or a mouse, but the marks it makes will seem to be from a pencil or pen or paintbrush. The second kind is 3D, where the screen becomes a window into a virtual environment, where you arrange objects to be "photographed" by the computer. Of course the image generated is 2D, so you can always take it into your paint program for additions, much in the same way the Weekly World Inquirer Magazine inserted the space aliens in the coffee bar.

If you look closely at your computer monitor, you'll see that the pictures and words are made up out of tiny dots. Each of these dots is under the control of your computer's display circuitry (except for the dots on the screen from opening your cola too close to the monitor). To generate the pictures and windows and boxes and words you see, it shuffles the data that describes these dots round and round as needed. The data behind the dots are called "pixels". Supposedly, this stands for "PIXture ELements." I think somebody just wanted to have an "x" in the middle of the word to sound futuristic.

To demonstrate - here's the letter "J":

Look at it up close... Take a magnifying glass to it if you like -- you won't get fried, although you may see some chromatic aberration at the edges of the magnifier. Check out the Physics entries of this or other encyclopedias. You see a "J", the computer sees something more like this:

00001

10001

01110

Where you see a zero, the computer instructs it's video hardware to paint the current background colour. A one calls for the current foreground colour. Yes, it is actually a bit more complicated, but it all basically boils down to one bit or the other making a distinction between the colours of adjacent pixels, which together form an image. This is the basic principle behind drawing on a computer. If we add a little more complexity, we can paint on it too...

The average human is said to be able to see and appreciate the difference between millions of colours. This varies, of course, by individual and environmental conditions and the kind of colours being viewed. However, for the sake of convenience, lets say millions. When computer programmers had to confront the problem, they said (for the sake of an even greater convenience), how about sixteen million? This happens to be a very easy number to deal with on a computer.

Most current computers are 32 bit processors. This means they can easily deal with numbers up to about four billion. They do this by representing each individual number as patterns of zero's and ones... Kind of like the example above.

[Explain (briefly) about RGB and mapping to bytes in word.]

[Discuss painting.]

[Image manipulation.]

Putting together a 3D image is totally different. Instead of being a painter, you work more like a studio photographer, arranging objects carefully in front of your computerized camera. Instead of a canvas, your screen is a window into this strange alternate reality, where you can manipulate things only through the proxy of your mouse or tablet pen.

To build a 3D image (actually, the image itself is usually (like most images) 2D, but you construct the elements that make up the image in 3D space), you first have to have objects to put in it. To get these objects, you must model them. The modelling process consists of describing the salient features of the object to the computer.

Depending on what type of software you're using, this might consist of building a kind of mechanical drawing of the object using a special "modeller" program (imaginative name, that). Or, you might simply describe the the object using a simple computer language. Once the shape of the object is defined, the surface properties are set up. These consist of the object's colour, texture, and roughness.

Now the object is built, it can be positioned in front of the virtual camera.Typically, you have are shown a view through the viewfinder of the camera, with other views down each major axis (X, Y and Z). These secondary views let you move the objects with precision -- it's impossible for the software to determine exactly how to move a particular object from just the viewfinder alone.

Once the objects are all arranged, it's time to turn on the lights. There are no shortage of virtual lights to go with your virtual camera. However, lighting is one of the most difficult arts to master. A simple repositioning changes a dramatic, moody scene into a direct product shot. Any book on theatrical or photographic lighting is helpful here.

The process of actually snapping the photo is called rendering. For speed and convenience during the setup process (all that above) the computer only shows simplified representations of the objects you're moving around. When you're actually ready to get a proper picture, the machine suddenly lets the hammer down on all that floating point math hardware you hardly ever use. It caclulates a simulation of the light leaving the light sources, bouncing around your scene and off the objects and then into your camera, exposing a virtual film plate. (That's why a render slows down if you add more lights, that much more simulation to do for each object in the scene.)

Because of the exacting nature of the process, it can take a long time. Many early artists waited days or weeks for their virtual snaps to develop. Thanks to the rising tide of processor speed and memory capacity, you probably won't have to wait that long, but be prepared to go get a cup of coffee while the image cooks. Depending, you might just want to step out for some lunch...

[Compositing.]

[Animation.]

[Output.]

[But is it art?]

[The future.]

MASSON - CG101, Terrence Masson, 1999, New Riders Publishing.