Material Null generates Visible Edges and Intersections

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FarbigeWelt
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Material Null generates Visible Edges and Intersections

Post by FarbigeWelt » Sun Aug 25, 2019 3:11 pm

LuxCoreRender V2.2 beta3, cd4f75b EDIT: also with LuxCoreRender V2.2 beta3, 1189665
Settings_Cubes Material Null, Spheres Material Glass Homogeneous
Settings_Cubes Material Null, Spheres Material Glass Homogeneous
If Material Null generated Visible Edges and Intersections intentionally this would be a nice feature sometimes. :lol:
Reproduction: Download and load scene
Cubes Material Null, Spheres Material Glass-Matte.zip
Cubes Material Null, Spheres Material Glass-Matte
(155.62 KiB) Downloaded 30 times
in Blender 2.79b and start render. After a few minutes openCL render is finished and the unwanted white lines and circles are good visible.
In my opinion, this rather unexpected feature is a bug. Developers, please run your pest controls. Thank you.
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kintuX
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Re: Material Null generates Visible Edges and Intersections

Post by kintuX » Sun Aug 25, 2019 5:28 pm

The visible edge is caused by the Sun/Distant Light.

No other light sources cause the issue, but render with much more noise!
Which feels like it will never clear. Well, at least not in any reasonable time :(

Here's with Area Light (and few other changes). ;)
Attachments
Cubes Material Null, Spheres Material Glass-Matte - Area Light.jpg

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Dade
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Re: Material Null generates Visible Edges and Intersections

Post by Dade » Mon Aug 26, 2019 8:38 am

I don't know how Blender works but are you using an array of cubes instead of a single big cube :?:

cubes.jpg

In this case, you are going to have a lot of problem with all the overlapped faces, (lack of) numerical precision will do a mess of your scene. Why aren't you using a single big cube ?
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kintuX
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Re: Material Null generates Visible Edges and Intersections

Post by kintuX » Mon Aug 26, 2019 9:05 am

Dade wrote:
Mon Aug 26, 2019 8:38 am
I don't know how Blender works but are you using an array of cubes instead of a single big cube :?:


cubes.jpg


In this case, you are going to have a lot of problem with all the overlapped faces, (lack of) numerical precision will do a mess of your scene. Why aren't you using a single big cube ?
Even so...
A single cube with Volume under Sun or Distant light produces visible edges.
BlendLuxCore & LuxCoreUI show same issue:

BlendLuxCore
SunEdgesVolume-BlendLuxCore.jpg

LuxCoreUI
SunEdgesVolume-LuxCoreUI.jpg
LuxCoreUI scene:
SunEdgesVolume_LuxCore.7z
(2.04 KiB) Downloaded 32 times

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Dade
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Re: Material Null generates Visible Edges and Intersections

Post by Dade » Mon Aug 26, 2019 9:33 am

The problem is quite easy to explain: the eye ray hits a front face however it doesn't detect the hit with the very near (on the edges) back face (due to numerical precision).

The result is a volume segment between the front face and the far camera clipping plane instead of between the front and back cube faces. A so long segment as a pretty much granted scattering event so you end with that kind of border.

It is easy to explain but I don't think it can be fixed :?:
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kintuX
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Re: Material Null generates Visible Edges and Intersections

Post by kintuX » Mon Aug 26, 2019 11:26 am

Dade wrote:
Mon Aug 26, 2019 9:33 am
The problem is quite easy to explain: the eye ray hits a front face however it doesn't detect the hit with the very near (on the edges) back face (due to numerical precision).

The result is a volume segment between the front face and the far camera clipping plane instead of between the front and back cube faces. A so long segment as a pretty much granted scattering event so you end with that kind of border.

It is easy to explain but I don't think it can be fixed :?:
A-OK. Common problem, like light leaking in a box w/o thick walls. ;)
LightLeak_WallNoThickness.jpg

:!: About a fix... looks like that reversing Normals and setting Volume to Exterior (outside) fixes the issue.
SunEdgesVolumeExterior-BlendLuxCore.jpg
Might be a bug elsewhere or somehow precision issue goes away :?

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FarbigeWelt
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Re: Material Null generates Visible Edges and Intersections

Post by FarbigeWelt » Mon Aug 26, 2019 5:04 pm

Dade wrote:
Mon Aug 26, 2019 8:38 am
I don't know how Blender works but are you using an array of cubes instead of a single big cube :?:
Yeas, there are several cubes. Edges show up although cubes do not overlap. Edges also show up, as kintuX showed, with single cubes.

There is also a another issue, first thought to be inner total reflections but this cannot be if Glass reflection is set zero. Reflection is not zero in these pictures but I can post some when I am at home. I do not think the edges effect and the ‚magic‘ walls in the Glass box glass have the same reason. The pictures with reflection of 0.0 are easier to read because in the one of this post there is a part of this walls indeed from reflections, a part from the glass container the other from the glass material liquid.
Attachments
02B02152-D634-4C30-9A5F-1502EC1E4FDD.jpeg
6FDB9B68-4FA1-48EA-88FA-1F3A3F63D630.png
F025D6A7-864F-4775-A26B-6877C31D4587.jpeg
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neo2068
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Re: Material Null generates Visible Edges and Intersections

Post by neo2068 » Mon Aug 26, 2019 6:46 pm

FarbigeWelt wrote:
Mon Aug 26, 2019 5:04 pm
Dade wrote:
Mon Aug 26, 2019 8:38 am
I don't know how Blender works but are you using an array of cubes instead of a single big cube :?:
Yeas, there are several cubes. Edges show up although cubes do not overlap. Edges also show up, as kintuX showed, with single cubes.

There is also a another issue, first thought to be inner total reflections but this cannot be if Glass reflection is set zero. Reflection is not zero in these pictures but I can post some when I am at home. I do not think the edges effect and the ‚magic‘ walls in the Glass box glass have the same reason. The pictures with reflection of 0.0 are easier to read because in the one of this post there is a part of this walls indeed from reflections, a part from the glass container the other from the glass material liquid.
Is the cube directly in the origin? I have seen such a behaviour when a glass cube is in the origin. Translating the scene out of the origin solved the problem.
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FarbigeWelt
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Re: Material Null generates Visible Edges and Intersections

Post by FarbigeWelt » Tue Aug 27, 2019 6:40 am

neo2068 wrote:
Mon Aug 26, 2019 6:46 pm
Is the cube directly in the origin? I have seen such a behaviour when a glass cube is in the origin. Translating the scene out of the origin solved the problem.
Cube‘s position might have been on the origin. I will later check if effect is related to origin position.
Light and Word designing Creator - www.farbigewelt.ch - aka quantenkristall || #luxcorerender
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FarbigeWelt
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Re: Material Null generates Visible Edges and Intersections

Post by FarbigeWelt » Tue Aug 27, 2019 7:21 am

kintuX wrote:
Mon Aug 26, 2019 11:26 am
:!: About a fix... looks like that reversing Normals and setting Volume to Exterior (outside) fixes the issue.

Might be a bug elsewhere or somehow precision issue goes away :?
Thank you kintuX for this cool and fresh idea switching volumes. I would never had this idea to step sideways on complex plane to get a better view on real part. Splendid! This new viewpoint helped me to find a generic solution for the quasi paradox situation when an object has different external volumes.
Generic solution
1) Priority of internal volume > external volume
2) External volume‘ priority is 0
3) All external volumes set to the same even if they are different in reality.
Reason: Overlapping part gwith higher priority replaces part of lower priority.
Possible Exception: Camera position is in a inner volume like in a set to take pictures underwater from a tree above water surface.
Correct volumes acc. to generic roules
Correct volumes acc. to generic roules
Light and Word designing Creator - www.farbigewelt.ch - aka quantenkristall || #luxcorerender
160.8 | 42.8 (10.7) Gfp | Windows 10 Pro, intel i7 4770K@3.5, 32 GB
2 AMD Radeon RX 5700 XT, 8 GB || Gfp = SFFT Gflops

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