Direct Light cache: how to avoid splotches?

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marcatore
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Direct Light cache: how to avoid splotches?

Post by marcatore » Fri Nov 16, 2018 8:57 am

Hi guys,
I'd like to share a real job I did for my company.
It's a good small project and I'd like to test LuxCore in a "easy" manageable project to reduce production risks.

I have to say that it was a good experience...the main difficult part was to be as much productive as I could reducing the "how should I do that kind of shader or what render options" phase.
DLSC.jpg
Now, as subject, I have a question for you.
I decided to use Direct Light Cache as I would have a real lighting scenario (actually the main reason is that is not possible to use "real" invisible area lights) and as you can see I have a lot splotches in the scene.
I've tried to raise the warmup samples number (I've tried up to 512 without any visual improvements) but it seems that it's not the reason for that.

What should I tweak to eliminate it?

I've tried using the LogPower strategy and it's fine but it has more noise.
I really like to use the DLSC but I'd like to understand more how it works and which kind of settings I should tweak for best results.
LogPower.jpg
About the lighting I have an emissive material with DLSC option enabled and the material is assigned just to this triangle (a question: when I have a sub material like this, the triangle count for lighting is just with poligon assigned with emissive material or all the main object?)
blender_2018-11-16_09-52-37.png

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Dade
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Re: Direct Light cache: how to avoid splotches?

Post by Dade » Fri Nov 16, 2018 9:10 am

Are you using glossy surfaces with high roughness values (> 0.2) ? Can you switch them to normal matte and retry ?
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B.Y.O.B.
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Re: Direct Light cache: how to avoid splotches?

Post by B.Y.O.B. » Fri Nov 16, 2018 9:12 am

marcatore wrote:
Fri Nov 16, 2018 8:57 am
(a question: when I have a sub material like this, the triangle count for lighting is just with poligon assigned with emissive material or all the main object?)
Only the parts with emissive material.
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marcatore
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Re: Direct Light cache: how to avoid splotches?

Post by marcatore » Fri Nov 16, 2018 9:32 am

Dade wrote:
Fri Nov 16, 2018 9:10 am
Are you using glossy surfaces with high roughness values (> 0.2) ? Can you switch them to normal matte and retry ?
Yes I'm using glossy surfaces...so just to understand, should I switch any materials in the scene?

I'll try.
B.Y.O.B. wrote:
Fri Nov 16, 2018 9:12 am
Only the parts with emissive material.
Thank you, so I did the right way. Is it correct?

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Dade
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Re: Direct Light cache: how to avoid splotches?

Post by Dade » Fri Nov 16, 2018 11:27 am

marcatore wrote:
Fri Nov 16, 2018 9:32 am
Yes I'm using glossy surfaces...so just to understand, should I switch any materials in the scene?
The one showing the splotches.
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marcatore
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Re: Direct Light cache: how to avoid splotches?

Post by marcatore » Thu Nov 29, 2018 4:00 pm

This is the result with matte materials applied to the particles of the floor carpet.
test_matte.jpg
As you can see the splotches are still visible, less then before but they're still visible.

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Sharlybg
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Re: Direct Light cache: how to avoid splotches?

Post by Sharlybg » Thu Nov 29, 2018 4:34 pm

What is your Warmup samples setting ? try to set it arround 512 -- 2048 or higher if splotches are still visible.
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marcatore
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Re: Direct Light cache: how to avoid splotches?

Post by marcatore » Mon Dec 03, 2018 2:34 pm

I've tried as suggested to rise the warmup samples.

512
test_matte_512_WarmUp_Crop.jpg
2048
test_matte_2048_WarmUp_Crop.jpg
It seems that a little but very little visually improvements is when I switch to 512... 2048 seems has the same quality of 512

In any case it doesn't solve

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Dade
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Re: Direct Light cache: how to avoid splotches?

Post by Dade » Mon Dec 03, 2018 2:37 pm

marcatore wrote:
Mon Dec 03, 2018 2:34 pm
In any case it doesn't solve
I need a test scene.
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lacilaci
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Re: Direct Light cache: how to avoid splotches?

Post by lacilaci » Mon Dec 03, 2018 3:06 pm

Dade wrote:
Mon Dec 03, 2018 2:37 pm
marcatore wrote:
Mon Dec 03, 2018 2:34 pm
In any case it doesn't solve
I need a test scene.
Isn't this always the same bug? I mean visually it always looks like the MIS issue with caching, or is it something different?

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