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Comment by coderdude | Hacker News Reader

I could be off the mark here but I'm fairly sure the world isn't ray traced. Ray tracing involves projecting light from the "eye" towards the scene, whereas in real life the light is being projected from the scene towards the eye.

By the way I was able to read the article. One thing I'd like to point out is that ray tracing lends itself better to parallelization because you can calculate each pixel's color independently of the others. That could be a major plus in the future that helps it win over scanline rendering.

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>Ray tracing involves projecting light from the "eye" towards the scene, whereas in real life the light is being projected from the scene towards the eye.

I can't write a decent reply to this without having terrifying flashbacks of late night cramming for third year physics exams. But basically, raytracing's idea that "if it didn't hit your eye, who cares" is somewhat backed up by theory =)

You mean the law of reversibility?

http://www.meritnation.com/discuss/question/32137

principle of reversibility of light: "The principle that if a beam of light is reflected back on itself, it will traverse the same path or paths as it did before reversal. The principle of reversibility states that light will follow exactly the same path if its direction of travel is reversed."

I was thinking more along the lines that without the eye, the idea of light being projected in any direction at all has no meaning =) And then we could get started on the concepts of time and ordering.

But since I'm no longer a third year physicist contemplating the nature of existence, I just simulate light statistically. And sometimes that means doing things like "Photon Mapping", which is precisely raytracing, but the kind of raytracing you get when you know how to optimize an algorithm implemented as a computer program.

http://en.wikipedia.org/wiki/Double-slit_experiment#Delayed_...

http://en.wikipedia.org/wiki/Interpretations_of_quantum_mech...

Ray tracing is not limited to working backwards from the eyes, it can work from the light source out. That just takes a lot more processing power.

Somewhere I heard that someone (either the ancient Greeks or Goethe) had conjectured or believed that vision actually was the result of rays projected from the eye.

Perhaps it was just an idea that's time had come too soon.

Plato's emission theory of vision. Or, why it's dark when you close your eyes.

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