Direct Light Sampling Cache errors

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lacilaci
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Re: Direct Light Sampling Cache errors

Post by lacilaci »

here, isolated issue (it seems like sky reflection is the problem)
hdri works normally, sky and sun works only if sky is not visible for glossy rays
If I add sun to hdri the issue appears again :lol:
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hdri.jpg
sunsky.jpg
sunsky_noskyvisibilityforglossy.jpg
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Dade
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Re: Direct Light Sampling Cache errors

Post by Dade »

lacilaci wrote: Sun Nov 11, 2018 11:18 am If I add sun to hdri the issue appears again :lol:
Yes, like I said, it is a MIS problem: if you set max path depth to 1 (in .cfg file), it works fine, if set to 2 (MIS enabled), it doesn't. It happens because some cache entry, near a shadow boundary, has 2 entries (sun+sky) others has sky only (sun always not visible there). This change the weights of MIS and triggers the problem.

It should be possible to recreate the problem also with just 2 area lights (i.e. it is not related the light source types but to Glossy code for Sample() and Evaluate()).
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lacilaci
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Re: Direct Light Sampling Cache errors

Post by lacilaci »

Dade wrote: Sun Nov 11, 2018 11:37 am
lacilaci wrote: Sun Nov 11, 2018 11:18 am If I add sun to hdri the issue appears again :lol:
Yes, like I said, it is a MIS problem: if you set max path depth to 1 (in .cfg file), it works fine, if set to 2 (MIS enabled), it doesn't. It happens because some cache entry, near a shadow boundary, has 2 entries (sun+sky) others has sky only (sun always not visible there). This change the weights of MIS and triggers the problem.

It should be possible to recreate the problem also with just 2 area lights (i.e. it is not related the light source types but to Glossy code for Sample() and Evaluate()).
When corona was introducing for the first time their new light solver that also handles many lights scenarios well. They too had similar issue I think: https://corona-renderer.com/forum/index ... #msg132828
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