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Re: Direct Light cache: how to avoid splotches?
Posted: Mon Dec 03, 2018 4:09 pm
by Dade
lacilaci wrote: ↑Mon Dec 03, 2018 3:06 pm
Isn't this always the same bug? I mean visually it always looks like the MIS issue with caching, or is it something different?
Only if it is glossy and I asked before (
posting.php?mode=quote&f=4&p=8053#pr7607) to redo the test with mate material so I assume the above rendering is showing a different problem
Re: Direct Light cache: how to avoid splotches?
Posted: Mon Dec 03, 2018 4:33 pm
by lacilaci
Dade wrote: ↑Mon Dec 03, 2018 4:09 pm
lacilaci wrote: ↑Mon Dec 03, 2018 3:06 pm
Isn't this always the same bug? I mean visually it always looks like the MIS issue with caching, or is it something different?
Only if it is glossy and I asked before (
posting.php?mode=quote&f=4&p=8053#pr7607) to redo the test with mate material so I assume the above rendering is showing a different problem
Well there's also the other issue which looks a lot like this one, when you use heavy clamping.. Remember? I think it's always the same thing going on, just very visible with heavy clamping and/or very rough reflections + multiple light sources.
Re: Direct Light cache: how to avoid splotches?
Posted: Mon Dec 03, 2018 4:36 pm
by lacilaci
And what's up with the spot made of bright pixels here? Related?
Re: Direct Light cache: how to avoid splotches?
Posted: Tue Dec 04, 2018 7:50 am
by marcatore
Dade wrote: ↑Mon Dec 03, 2018 4:09 pm
lacilaci wrote: ↑Mon Dec 03, 2018 3:06 pm
Isn't this always the same bug? I mean visually it always looks like the MIS issue with caching, or is it something different?
Only if it is glossy and I asked before (
posting.php?mode=quote&f=4&p=8053#pr7607) to redo the test with mate material so I assume the above rendering is showing a different problem
I sent you a PM with the scene.
About the carpet on the floor I confirm I used a matte material
Re: Direct Light cache: how to avoid splotches?
Posted: Tue Dec 04, 2018 11:08 am
by Dade
lacilaci wrote: ↑Mon Dec 03, 2018 4:36 pm
And what's up with the spot made of bright pixels here? Related?
The first step when checking a DLSC related problem is always to switch max. path depth to 1 so you will see only direct light sampling:
It becomes quite evident that at glancing angles the information of the cache are not correct due to "normal threshold" (10 degrees in this case). If you lower the normal angle threshold to 4 degrees (and increase the radius to 15cm just to speed up the pre-processing):
and with full path depth:
Re: Direct Light cache: how to avoid splotches?
Posted: Tue Dec 04, 2018 11:12 am
by Dade
marcatore wrote: ↑Tue Dec 04, 2018 7:50 am
I sent you a PM with the scene.
About the carpet on the floor I confirm I used a matte material
Thanks, going to check but I have the strong feeling the problem is in the impossibility to have reliable cache information over the carpet (the particle system for hair simulating the carpet will likely to generate a surface over which is impossible to interpolate correct information).
Re: Direct Light cache: how to avoid splotches?
Posted: Tue Dec 04, 2018 11:37 am
by marcatore
Some exclude list or something else to help the engine with samples estimation?
Could be helpful in this case?
Re: Direct Light cache: how to avoid splotches?
Posted: Tue Dec 04, 2018 11:39 am
by lacilaci
marcatore wrote: ↑Tue Dec 04, 2018 11:37 am
Some exclude list or something else to help the engine with samples estimation?
Could be helpful in this case?
Or maybe retracing problematic areas if they can be identified...?
Re: Direct Light cache: how to avoid splotches?
Posted: Tue Dec 04, 2018 1:19 pm
by FarbigeWelt
Dade wrote: ↑Tue Dec 04, 2018 11:08 am
lacilaci wrote: ↑Mon Dec 03, 2018 4:36 pm
And what's up with the spot made of bright pixels here? Related?
The first step when checking a DLSC related problem is always to switch max. path depth to 1 so you will see only direct light sampling:
prob1.jpg
It becomes quite evident that at glancing angles the information of the cache are not correct due to "normal threshold" (10 degrees in this case). If you lower the normal angle threshold to 4 degrees (and increase the radius to 15cm just to speed up the pre-processing):
fix1.jpg
and with full path depth:
fix2.jpg
Wow! This is a good step by step instruction for DLSC related issues. Thank you much, Dade.
Re: Direct Light cache: how to avoid splotches?
Posted: Wed Dec 05, 2018 8:43 am
by lacilaci
If I remember correctly, vray has this retracing threshold value for Light caching, I guess it's a workaround to deal with these type of problematic areas...? If we could detect shadow borders and these areas where cache has problems, maybe we could force "retracing" those areas, replacig cache with brute force?