The biggest mistake that most computer graphics artists make is to throw too much light onto their models to show them off, but how do you use digtal light to your advantage? This month Brian gives his advice...
An illuminating story by Brian K. DrescherWhat is the one of the first things you notice in a computer generated image or animation that you don't really like. Is it a badly made model? Is it a badly animated model? Or is it the buckets of light the creator threw onto the model to show everyone how clever she or he is?
These items always seem to go hand in hand with bad computer graphics. Because of the onset of better and cheaper computer graphics software and hardware, the logical progression is for loads of really bad imagery, and a precious few that fly above the rest. What makes the good work really note worthy, and the bad work really irritating? Attention to detail! This holds true for all levels of the creative process whether it be the story or theme, the modeling, or the overall execution and realization of the image.
The most memorable images, animation's, films, or commercials usually come from a source with bags of money behind them. Bags of money mean the best of the best. What exactly do those bags of money pay for? The best agencies, studios, and operators that money can buy. How did these simple humans attain this level of perfection and sublime insight? Again, simple attention to the details. Even the worst models, animation's, and sometimes the stories can be forgiven if the imagery blends into existing scene, or takes on a life of it's own because of believability. And for me one of the most important and most overlooked elements is the quality of light that the subject receives. Therefore this article is focused on a subject that most computer graphics people ignore the quality and believability of light.
LET THERE BE DIGITAL LIGHT
Without light, we see nothing. Computer graphic models of light seek to emulate the effect of a light source bouncing off of the surface of an object as it would in the "real world" to the human eye. In the beginnings of computer graphics programmers were concerned with creating the surfaces that would accept the light that the observer would recognize as a shape in 3D space. Once the geometry of surfaces could be defined, the next logical problem was to model the light to simulate surfaces that we all could accept as objects. Therefore the creation of the models of objects and the models of light were from the start tightly bound. As physical objects can be defined, so too can light be defined...mathematically.But why then do computer generated images have that unreal sharp look? Because the models of light and the models of objects are too generally defined. The real world has much more "dirt" than any computer model could ever hope to encompass. Think of the simple circumstance of a single 60 watt light-bulb illuminating your kitchen. That single source is able to illuminate without any difficulty every object it encounters with enough detail to tell your eye and mind that the room is filled with three-dimensional objects. If you re-created the exact same kitchen in your computer graphics system down to the finest detail, and illuminated it with a similar light source, it just wouldn't work...why? To simulate all of the nuances of light that illuminate all of the objects in that kitchen would take the biggest computer a human lifetime to re-create. There is just too much beautiful "dirt" to take into account. Raytracing, radiosity, frequency interference rendering, or just simple shaders can't cut it!. So what does a simple human computer enthusiast do?...CHEAT!
FANTASY VS. REALITY
What is the best way to learn to illuminate a computer generated scene? Think back to the first "Jurassic Park" film. Those dinosaurs where amazing weren't they? But why? Forgetting all of the complex modeling of flesh, muscles, and textures, they blended in perfectly to the environments because the models matched the lighting of the set EXACTLY! If you create a 100% computer generated scene and illuminate it the best you can, it never really meets the criteria of a "real life" setting. That is because you are trying to re-create the lighting as you imagine it SHOULD BE based on pre-set conceptions you have regarding how light SHOULD LOOK in a specific situation. But no human can be expected to imagine all of the subtle possibilities in a given situation. You expect that your computer software will "fill in the gaps" for you, but alas, the software was also written by mere humans. To learn how to light a computer generated scene the best technique is to composite a computer generated object into an existing "real" environment. It is only then that you will realize how little light is required to achieve a believable result.BUCKETS-O-LIGHT
The biggest mistake that most computer graphics artists make (beginning or not) is to throw too much light onto their models to show them off. My advice is to learn about mathematical models of light, and practical circumstances of lighting situations. KNOW what quadratic light is (what you see is quadratic light...the inverse square law). Don't be tempted by linear light sources, don't be tempted by constant light sources, they are all models of perfect situations of mathematical light that don't exist in the real, or any other world. Don't be afraid to use lots and lots of tiny light sources to fake the effects of radiosity and reflected light. Know how to use your objects surface attributes to make the most of the lighting situation. My Philosophy is...add light with an eye-dropper not a fire-hose!KNOWLEDGE IS GOLDEN
If you want to be a unique computer graphics artist my advice is to go to the library (it's old fashioned I know) and to study books on photography, cinematography, film, and most important LIGHT. If you are really motivated, you should take some photography courses, or try to sit in with a professional photographer that is making images of a simple object such as a table-top setting or a studio shot. If you are really motivated, try to get involved with a crew filming a commercial or motion picture...these are the kinds of humans that know how to make light work for them and not against them. You will creating an artificial world, but it still has to agree with the conventions that we are all used to observing.LIGHTING LIGHTLY
So, with the above knowledge you are commanded with a respect for light. Use it carefully, and it will give you the unique factor that you will require to give your imagery the signature that will make people say...HOW DID THEY DO THAT?
If you want more information about light models, or if you have questions don't hesitate to contact me.BRIAN K. DRESCHER - AMSTERDAM
email: bkdresch@xs4all.nl
homepage: http://www.xs4all.nl/~bkdresch