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by GuB-42 250 days ago
Global illumination is the hard part. The math isn't that hard, but even the best render farms don't have enough computing power to support a straightforward implementation.

So what follow is an endless series of tricks. Path-tracing is one of the purest implementations, and it is actually a simple algorithm to implement, but if you don't want to have a noisy mess on all but the most simple shapes, now we are talking PhDs and rock star developers.
2 comments
Lwerewolf 250 days ago
Would you mind linking some articles or hinting towards techniques used to "coerce" the choosing of ray sample directions so that noise is minimized even in very "specular" scenes? Sorry for the lack of proper terminology on my end, I've been out of the loop for a very long time, but I assume that's where the majority of the tricks are - I suppose the rest is mostly intersection check accelerations (i.e. BVH).
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omcnoe 249 days ago
The modern state of the art for realtime is ml denoisers, taking noisy pixel data from multiple frames, plus other associated data eg velocity vectors of geometry, depth data etc. and using it to produce a perfectly denoised image.
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Sohcahtoa82 249 days ago
"perfectly" is doing some heavy lifting here.

Right now, I'm heavily into Cyberpunk 2077. I've got an RTX 5090, so I can turn all the details, including the ray tracing, to their maximum settings. It's absolutely gorgeous (Especially on my 4K HDR OLED monitor), but if you look really closely, you can still see the evidence of some shortcuts being taken.

Some reflections that are supposed to be a bit rough (like a thin puddle in the road) may appear a bit blurry as I'm walking, but will come into better focus when I stop. My guess is that as I'm moving, the angles of the rays being reflected change with every frame, making the data very noisy. Once I stop, they become consistent, so the reflection becomes clear.

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namibj 249 days ago
Metropolis light transport is a big one.
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nomel 249 days ago
> but even the best render farms don't have enough computing power to support a straightforward implementation.

Back in 2014, Disneys Hyperion farm supported 10-20 software bounces! [1] Does this count, or does it still require "cheats"?

[1] https://www.engadget.com/2014-10-18-disney-big-hero-6.html

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