Light bounce quality

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Sharlybg
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Light bounce quality

Post by Sharlybg »

Just continue my testing journey . now while trying to see how much brightness/light detail i can get while increase path deph (same number for all diffuse/glossy/specular) :

8
ar___8_total__deph.png
16
ar__16__total__deph.png
64
ar__64__total__deph.png
128
ar__128__total__deph.png

Was now feeling that the Lux RR default parameter to be a bit aggressive. So i wonder how it will turn if can tune this RR setting. Where can i find it ? it is not exposed i think.
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B.Y.O.B.
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Re: Light bounce quality

Post by B.Y.O.B. »

The properties are described here: https://wiki.luxcorerender.org/LuxCore_ ... PATHCPU.22
You're probably looking for "path.russianroulette.depth" and "path.russianroulette.cap".

In the addon, you can add these here for testing: https://github.com/LuxCoreRender/BlendL ... fig.py#L51

It's easiest to add a hardcoded line, something like

Code: Select all

"path.russianroulette.depth": 3,
however note that when you change this value, you will have to restart Blender so the change takes effect.
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Re: Light bounce quality

Post by Sharlybg »

thanks you BYOB for this nice input. going to try this now. Btw i can understand this feature :

path.russianroulette.depth : The path depth where Russian Roulette stars to be used

but this one i don't really catch it :

path.russianroulette.cap : The threshold over which Russian Roulette is used

threshold of what ?
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Dade
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Re: Light bounce quality

Post by Dade »

Sharlybg wrote: Wed Jan 29, 2020 11:09 am but this one i don't really catch it :

path.russianroulette.cap : The threshold over which Russian Roulette is used

threshold of what ?
It is a value between 0.0 and 1.0: higher it is and less likely RR will be applied (1.0 => never applied). It is based on the material luminance: RR applied to small values tends to cause fireflies.
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Re: Light bounce quality

Post by Sharlybg »

It is a value between 0.0 and 1.0: higher it is and less likely RR will be applied (1.0 => never applied). It is based on the material luminance: RR applied to small values tends to cause fireflies.
it is very well explained thanks you !
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Re: Light bounce quality

Post by Sharlybg »

By the way before i change anything in RR default setting here is the light quality difference between Path+PGI vs Bidir. Note how natural / bright / and progressive is the light from Bidir engine .


Bidir
ar__24+16__Bidir__deph.png
Pathocl+ Pgi
ar__40__path__deph.png

theses kind of light treatment difference lead to a great realism boost ;) look the light in the back of the sofa and also light bouncing on the horizontal grid in front behind the second glass.
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Re: Light bounce quality

Post by Sharlybg »

It is a value between 0.0 and 1.0: higher it is and less likely RR will be applied (1.0 => never applied). It is based on the material luminance: RR applied to small values tends to cause fireflies.
Btw for simplicity this value can be named ""RR strenght"" while we inverse the behaviour : higher it is and more likely RR will be applied (0.0 => never applied).

More intuitive for artist.
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Re: Light bounce quality

Post by Dade »

Sharlybg wrote: Wed Jan 29, 2020 12:16 pm By the way before i change anything in RR default setting here is the light quality difference between Path+PGI vs Bidir. Note how natural / bright / and progressive is the light from Bidir engine .
Have you increased the max. photon bounces ?

P.S. BiDir default max. is 16, PGI is 4
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Re: Light bounce quality

Post by Sharlybg »

B.Y.O.B. wrote: Wed Jan 29, 2020 10:45 am The properties are described here: https://wiki.luxcorerender.org/LuxCore_ ... PATHCPU.22
You're probably looking for "path.russianroulette.depth" and "path.russianroulette.cap".

In the addon, you can add these here for testing: https://github.com/LuxCoreRender/BlendL ... fig.py#L51

It's easiest to add a hardcoded line, something like

Code: Select all

"path.russianroulette.depth" = 3,
however note that when you change this value, you will have to restart Blender so the change takes effect. You can do this by pressing the F5 key in a 3D viewport.
After i add theses lines i can't enable luxcore in blender addon without syntax error :

Code: Select all

 # Common properties that should be set regardless of engine configuration.
        definitions.update({
            "path.russianroulette.cap" = 1,
            "path.russianroulette.depth" = 3,
            "renderengine.type": luxcore_engine,
            "sampler.type": sampler,
            "film.width": width,
            "film.height": height,
            "film.filter.type": filter_type,
            "film.filter.width": config.filter_width,
            "lightstrategy.type": light_strategy,
            "scene.epsilon.min": config.min_epsilon,
            "scene.epsilon.max": config.max_epsilon,
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Sharlybg
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Re: Light bounce quality

Post by Sharlybg »

Have you increased the max. photon bounces ?

P.S. BiDir default max. is 16, PGI is 4

Photon deph was set to 40 to avoid any bottleneck :
pgi deph 40.jpg
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