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What’s the most important thing in CG?

Posted: 06.02.08

Resistance is futile—you should believe

That might beg the question, “what exactly is CG,” but I’m going to sidestep that discussion because it might distract from my main point, which is that the most important thing in CG is photons. Too easy? OK, the most important thing in CG is sending a hellofa lot of colored photons, big fat photons called pixels to your central nervous system via the eyes.

OK, still too easy. I guess I am going to have to define CG. Ready? CG is the suspension of disbelief about the origin of what you see, and if done correctly, what you feel (physically and emotionally); well done CG is like a Turing test.

So with that definition, what’s the most important thing? Tricking the eyes and the computer system behind them all the way to your toes. In fact, that could be the ultimate test of suspension of disbelief, when you look at a CG image and curl up your toes in either fear or titillation—we could call it the toe-curl test and rate it on a scale of one to 10 with 10 being that it takes 10 minutes or so for you to manage to uncurl your toes and get the circulation back.

I’ve been wandering around the world lately, giving talks about CG and I have three images I like to use to make the point.

Of those three images, and subject to how you’re viewing them (on a screen or the printed page), which ones do you think are real—i.e., a photograph and which are CG? Take your time, I’ll wait. Da da dum de dum. OK, ready? The one on the left is a raytraced image, the one in the middle is a raster image, and the one on the right is a photograph of a painting. I’d guess everyone got number three—the Hopper painting. Most people I’ve given this test to don’t get the middle one, and depending on how I lead the audience most don’t get the first one either. So that’s pretty good suspension of belief, no?

But here’s the deal. Some of you identified all three correctly. Now, maybe that’s because you have trained eyes like me, or you’re just smart. Regardless, you weren’t tricked, and that’s what CG is all about—tricking you. And if you’re sitting in the cockpit of a simulator and you don’t get tricked, when you’re in the real deal you get dead.

So what’s the most important thing in CG? Tricking the viewer. Period. And how do you do that? With lots of pixels that relate to each other and the mind’s eye. Can you be tricked on a 15-inch 1024 x 768 screen, or a 17-inch 1280 x 1204, or even a 20-inch 1680 x 1050 screen? No. But you can come close on a 30-inch 2560 x 1600, and two of them jammed tightly together can get you even closer. Now if you had two 30-inch screens, you’d need some hefty pixel pushers because you’re talking about 8.2mpixels at least 30 times a second and all the pixel polishing that goes on behind those displays to get you to curl your toes.

And that is the heart of the issue and what CG is all about—compensa­ting for limited bandwidth, compute cycles, memory, and database delivery to create a sequence of unique (no MPEG here folks) images that will, well you know, the toe thing. CG is trickery to compensate for lack of resources—and sometimes we actually make it happen. All of which leads us to Peddie’s first law—in CG too much is not enough, and Peddie’s second law—the more you can see the more you can do (as in suspend disbelief). And that, boys and girls, is what gets us out of bed in the morning—working the tricks.

Final word

We’re not supposed to resist suspension of disbelief. We’re supposed to embrace it. So, in the examples you’ve just seen, we’re really supposed to want to believe.