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Comment by hiker | Hacker News Reader

Most of the progress in the field came from the pursuit of photorealism and trying to simulate better what actually happens in reality.

The path tracing approaches in modern raytracers are actually very similar as computation to Feynman's path integral formulation of quantum electrodynamics (QED). The big difference is that in the "classical" approach one integrates real values (radiance) and in the QED one integrates complex values (amplitudes) whose magnitude describe the probability of a given wavelength hitting the camera sensor.

I was pitching this idea as a research direction in a recent slide deck https://github.com/skaslev/fract/blob/master/mc-production.p...

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It's seductive to believe that if we just use a clever model, we can create something that looks real.

It's not that simple. By definition, the closer that your engine looks to real life, the less flexibility artists have. If a scene looks perfectly real, artists would not be allowed to change anything at all, because any change would make the scene look less real.

Therefore, no matter what kind of clever mathematics you use, or any algorithm you come up with, your flexible art pipeline will torpedo your ambitions of creating a CG video indistinguishable from real life.

This is a fundamental limitation that I don't think has been fully appreciated, or at least isn't emphasized in literature. I think most people can't really believe or accept that no one, anywhere, has ever successfully created a CG video of a complex scene that is capable of fooling all human observers 100% of the time. (If a set of human observers are asked "Is this video real, or computer-generated?" then their responses should be no better than random chance.)

Your research looks promising! It would be interesting to pair an analytic solution with some hypothetical art assets that were somehow generated from reality, or otherwise fully capture all of the variables in a real-life object (i.e. the textures are more than simply RGB values).

Imagine you are remaking Raise The Titanic.

The original film had a very renowned detailed model 15m long and weighing 10 tons. It was quipped that it would have been cheaper to lower the Atlantic.

Now imagine in your remake you choose to raise a virtual photo-realistic Titanic. Your artists and critics are not going to complain that it is too realistic.

Realistic rendering is strived for even when the scene being rendered is conjured up by artists.

Certainly. But the point is, if a scene is conjured up by artists, the material they work with -- the RGB textures they create, the specular maps, etc -- do not in any way match real life, or real objects. They make those textures with the goal of getting an engine to display results that look sufficiently good.

That means if you're interested in creating a truly realistic CG video, you have no hope of succeeding if you use an art pipeline. If it's true that a truly realistic CG video will only be created by data that matches real life, then artists must not be allowed to conjure up the data that you use. The data has to come from real-life sources.

There is a contradiction here, and I think it's worth accepting and embracing it. Once you accept that true realism isn't the goal, then you can focus on making CG look cool.

Physically Based Rendering[0] is big these days. Materials can be acquired using special scanners[1]. The result is that you can have a library of materials that behave in predictable ways in a wide variety of situations. Artists still have a lot of freedom, they can chose materials and change lighting, just like in a real photo shoot.

[0] https://en.wikipedia.org/wiki/Physically_based_rendering [1] https://www.chaosgroup.com/vrscans

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