PhotonGI cache

Discussion related to the Engine functionality, implementations and API.
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epilectrolytics
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Re: Cache combination problem

Post by epilectrolytics » Thu May 09, 2019 12:07 pm

Dade wrote:
Wed May 08, 2019 2:43 pm
I should have fixed the problem in the latest sources.
Thanks for looking into this!
Now the cache size is not restricted any more but there are still firefly photons appearing when the indirect cache is added and they persist however I change the settings.
causticcache.png
Note: your caustic merge radius (~0.019) is wrong, just use the default value (0.25).
The quality of refractive caustics at merge radius 0.25 is just awful, see comparison with BiDir and radius 0.02 below:
PGI.jpg
Yes, I could add also glossy nearly-specular materials to the set of materials supported by the cache.
That would be very welcome, for glossy, metal and the upcoming principled materials.
In the image above you see how PGI renders the reflective caustics of the left cube (metal material with fresnel color 0.25 and roughness 0.01) with brute force and produces caustic noise slowly to converge.

In most interior renders there is a shiny floor material made with a glossy material node.
This is slow to render because of brute force caustic noise and also introduces bias because the indirect cache misses the view dependent part of glossy reflections.
Probably with a small (big merge radius) caustic cache for those glossy reflections the caustic noise would be prevented and also the light distribution bias reduced :idea:
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Re: Cache combination problem

Post by provisory » Fri May 10, 2019 11:16 am

epilectrolytics wrote:
Thu May 09, 2019 12:07 pm
Yes, I could add also glossy nearly-specular materials to the set of materials supported by the cache.
That would be very welcome, for glossy, metal and the upcoming principled materials.
+1 :!:

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lacilaci
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Re: PhotonGI cache

Post by lacilaci » Fri May 17, 2019 11:52 am

Are there going to be some changes to direct light sampling/caching aswell for 2.2?

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Egert_Kanep
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Re: PhotonGI cache

Post by Egert_Kanep » Mon May 20, 2019 9:30 am

Would it makse sense to have photongi defined with bounding boxes in Blender. Like eevee has those separate objects for areas where you want to have gi. It would help in a scenario if you have one object, that would need caustics, then you could just put a gi object around that particular area and use different photon count for that area and only for caustics. The rest of the scene could use another gi object with different settings.

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Re: PhotonGI cache

Post by provisory » Sat May 25, 2019 3:03 pm

Can I exclude a light (or Emission node) from PhotonGI caustics?
The Material Output's Use PhotonGI Cache checkbox doesn't seem to work for this.

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Dade
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Re: PhotonGI cache

Post by Dade » Sat May 25, 2019 3:25 pm

provisory wrote:
Sat May 25, 2019 3:03 pm
The Material Output's Use PhotonGI Cache checkbox doesn't seem to work for this.
The flag is used to decide if you can have cache entries over the surface using that material or just use brute force path tracing (i.e. it is the receiving end of light, not the emitting one).
If you have some PhotonGI artifact, you can use this flag to force normal path tracing and avoid the problem.
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Re: PhotonGI cache

Post by provisory » Sat May 25, 2019 3:36 pm

Thank you!

I have a mirror surface that I would like to reflect a smaller, definite direction light. But there are other, larger lights, that illuminate the whole scene. For the small light small lookup radius would be good, but with that the larger lights make terrible caustics. The simplest solution would be to turn off caustics for those larger lights.

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