power/cache/logpower

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lacilaci
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power/cache/logpower

Post by lacilaci » Tue Jun 04, 2019 2:13 pm

cache quality is terrible with logpower - especially if there is more than 1 light illuminating the scene (there is always more than one light)

this often results in splotches in cache which can look pretty bad in reflection...

cache with power:
power.jpg
cache with logpower:
logpower.jpg
This problem also makes next problem more obvious,

In archviz you often have thin objects that are close to walls.. For example you might have a grey/white floor and on that floor dark floor boards, which might be very thin objects. Since they are thin, a bright cache might be generated on that area (especially with logpower) and this bright cache entry can get very visible in some reflection or lighting. This issue can be minimized of course by disabling cache on those thin objects but if by some miracle there is a way to make it work even in that case it would be great.

I'm sorry I cannot provide testscene for this and I'm gonna be very busy with interiors for a while so I can only complain and show some pictures from time to time.

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epilectrolytics
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Re: power/cache/logpower

Post by epilectrolytics » Wed Jun 05, 2019 8:59 am

I think the problem is with infinite lights, somehow PGI is unable to produce an even distribution of photons from infinite lights like the sky.

Image

Now log power gives more weight to those uneven sky samples than power does (compared to sun samples).
I've encountered this various times and apart from the glossy reflection problem you mentioned it also destroys the caustic cache whenever there is some background light in the mix.
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B.Y.O.B.
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Re: power/cache/logpower

Post by B.Y.O.B. » Wed Jun 05, 2019 9:23 am

Did you use the default settings for this, or if not, can you post a screenshot of your settings?
Nowadays, when I enable PGI, I just leave everything at the defaults and it seems to work well (but I usually don't look at the cache).
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lacilaci
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Re: power/cache/logpower

Post by lacilaci » Wed Jun 05, 2019 9:36 am

I used defaults, and I also don't look at the cache when it works but sometimes with logpower I get really rough cache that has these spikes that also show in reflections. When I then set direct light sampling to power cache is smoother and so are glossy reflections.

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