PhotonGI cache

[Dade]

BTW, I forgot to write that my work on Metropolis is based on "Robust Adaptive Photon Tracing using Photon Path Visibility" by TOSHIYA HACHISUKA and HENRIK WANN JENSEN: https://www.ci.i.u-tokyo.ac.jp/~hachisuka/amcmcppm.pdf

[lacilaci]

BTW, I forgot to write that my work on Metropolis is based on "Robust Adaptive Photon Tracing using Photon Path Visibility" by TOSHIYA HACHISUKA and HENRIK WANN JENSEN: https://www.ci.i.u-tokyo.ac.jp/~hachisuka/amcmcppm.pdf

The question is now... will caustic rendering become "mainstream" in luxcore before corona?

[Dade]

I added the support for building and using visibility information with Metropolis. This is a zoom out view of the cache for Psor's cube without using visibility information:

All the ground surface is covered with photons. The same cache using the visibility information:

99% of photons lands only on the seen rectangle of the ground (with the original camera position).

This is a quite hard rendering with a light source outside the room and light coming in only trough small rectangular holes, with Random sampler and no visibility information:

With Metropolis but no visibility information:

And with Metropolis and visibility information:

Clearly plain Metropolis is better than Random and Metropolis+Visibility is better than plain Metropolis.

The Visibility information is currently build with a single thread, next step multi-thread support.

[epilectrolytics]

Great progress, very exciting!

How will this work with displacement or objects with high instance count blowing cache size out of proportion, can those be excluded or some kind of averaging applied?

[Dade]

How will this work with displacement or objects with high instance count blowing cache size out of proportion, can those be excluded or some kind of averaging applied?

You can disable the cache on a per material base in order to render nearly-specular glossy surfaces or surfaces with too many details:
viewtopic.php?f=5&t=840&start=30#p8885

With cache disable, normal path tracing will be applied, bouncing over the surfaces and probably hitting another surface where cache is enabled (so still indirectly benefiting of the cache speedup).

[lacilaci]

does it work well with clamping?

[epilectrolytics]

With cache disable, normal path tracing will be applied, bouncing over the surfaces and probably hitting another surface where cache is enabled (so still indirectly benefiting of the cache speedup).

Ingenious!

[Sharlybg]

I'm afraid all this is going too far. Can we stop now ?

Nooooooooooooo

[Dade]

does it work well with clamping?

As far as I have seen, yes, there no particular problems with clamping.

[epilectrolytics]

As far as I have seen, yes, there no particular problems with clamping.

Don't know if it is a clamping issue, but for the caustic cache clamp value = 1 is required and in my test scene caustics are muted and the light balance is very different when compared with a bidir metro render.
But for the first time we get fast caustics with correct SDS reflections, yay!
Also the innovative metropolis photon distribution works great, no problem with insane photon counts for smooth caustics.
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cachetest_LuxCore.zip

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