Homogeneous volume absorption depth

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wasd
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Homogeneous volume absorption depth

Post by wasd »

Blender 2.79b
LuxCore 2.1 alpha0
CPU Path + Metropolis (also BiDir + Metropolis and Path/BiDir + Sobol)

Glossy Translucent Material with interior homogeneous volume
I can't see any difference, though every ball have different absorption depth
From left to right: 0.01 mm, 0.1 mm, 1 mm, 1 cm, 1 m, 10 m, 100 m
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b5.png
CPU Bidir + Metropolis | Core i5-4570
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B.Y.O.B.
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Re: Homogeneous volume absorption depth

Post by B.Y.O.B. »

The transmission color of the glossy translucent mat is black, so the volume does not make any difference because no light is transmitted.
wasd
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Re: Homogeneous volume absorption depth

Post by wasd »

B.Y.O.B. wrote: Thu May 17, 2018 3:03 pm The transmission color of the glossy translucent mat is black, so the volume does not make any difference because no light is transmitted.
Do you have an example scene, which shows the difference in absorption depth? I still cannot figure out how absorption depth affects the material.
This scene has transmission color 7F7F7F at all balls.
Attachments
b6.png
CPU Bidir + Metropolis | Core i5-4570
kintuX
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Re: Homogeneous volume absorption depth

Post by kintuX »

Yes, looks like it's something wrong in Blender.
Volume_trans_Abs_bug.jpg
PS.
It works fine in Material Preview, but not in Render Preview nor in Final render.
Last edited by kintuX on Thu May 17, 2018 7:02 pm, edited 1 time in total.
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B.Y.O.B.
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Re: Homogeneous volume absorption depth

Post by B.Y.O.B. »

wasd wrote: Thu May 17, 2018 3:52 pm Do you have an example scene, which shows the difference in absorption depth? I still cannot figure out how absorption depth affects the material.
The absorption depth is the distance after which a white light ray (1, 1, 1) has the color that is specified as absorption color.
You can see the effect best with the null material.
wasd
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Re: Homogeneous volume absorption depth

Post by wasd »

B.Y.O.B. wrote: Thu May 17, 2018 5:40 pm
wasd wrote: Thu May 17, 2018 3:52 pm Do you have an example scene, which shows the difference in absorption depth? I still cannot figure out how absorption depth affects the material.
The absorption depth is the distance after which a white light ray (1, 1, 1) has the color that is specified as absorption color.
You can see the effect best with the null material.
What about an example?
CPU Bidir + Metropolis | Core i5-4570
wasd
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Re: Homogeneous volume absorption depth

Post by wasd »

OK. I get it. Volumes just don't really work with anything but Null material.
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machine-le-grass-test-ej.blend
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Скриншот 2018-05-18 01.32.26.png
Скриншот 2018-05-18 01.32.13.png
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Re: Homogeneous volume absorption depth

Post by B.Y.O.B. »

Volumes are independent from materials.
The material describes the surface, the volume describes everything inside or outside of the surface.

You might see something else than you expect because the material reflects too much light and transmits too little?

From left to right:
- Null
- Matte Translucent
- Glossy Translucent
- Glass
- Rough Glass

Hope this helps.
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volume_depth_example.blend
(883.66 KiB) Downloaded 294 times
volume_depth_example.jpg
wasd
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Re: Homogeneous volume absorption depth

Post by wasd »

B.Y.O.B. wrote: Thu May 17, 2018 7:56 pm You might see something else than you expect because the material reflects too much light and transmits too little?
Maybe.
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Скриншот 2018-05-18 03.38.55.png
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Dade
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Re: Homogeneous volume absorption depth

Post by Dade »

wasd wrote: Thu May 17, 2018 8:46 pm Maybe.
You are confusing object transparency (or opacity if you prefer) with object surface+volume. Transparency makes all object (surface+volume) transparent, like with alpha channel. In your case must be set to 0, it is not what you are looking for.

The object material describes the surface (i.e. the "skin") of an object while volume describes the interior.
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