openCL render issues: unknown pattern, sporadic white particles with Matte translucent

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FarbigeWelt
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openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by FarbigeWelt » Thu Oct 17, 2019 11:47 am

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LuxCoreRender version 2.3, 'latest', build: d5e6dfe
BlendLuxCore version 2.3, 'latest build', build: 39f6ad5

Windows 10 Pro, Version 1903, Build 18362.418; Intel core i 7 4770K; 32 GB DDR3, 1333 MHz
2 openCL devices: gfx1010 aka AMD Radeon RX 5700 XT, 8 GB 1755 MHz, compute units: 20, work group size: 256
OpenCL 2.1 AMD-APP (2906.10); Radeon Software Version 19.10.1
OpenGL version:	4.5.13571 Core Profile Context 19.10.1 26.20.13025.10004

Blender version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: f6cb5f54494e, type: build date: 2019-07-29, 09:44 AM
Python version: 3.7.0 (default, Aug 26 2018, 16:05:01) [MSC v.1900 64 bit (AMD64)]
Enabled add-ons: BlendLuxCore (version: (2, 3), TheGrove7 (version: (7, 4)
I think the following images speak for themselves.

openCL render issues: unknown pattern :!:
Strange, yet unseen pattern in sky render
Strange, yet unseen pattern in sky render
Sporadic white particles with Matte translucent :?
Matte Translucent renders white particles (leaf objects)
Matte Translucent renders white particles (leaf objects)
Did someone else observe one of these effects too?
Does somebody know reasons for the two cases?
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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Dade
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by Dade » Thu Oct 17, 2019 9:43 pm

FarbigeWelt wrote:
Thu Oct 17, 2019 11:47 am
openCL render issues: unknown pattern :!:
Strange, yet unseen pattern in sky render.png

Did someone else observe one of these effects too?
I have noticed this problem only sometime and only in the very first samples than disappears after a couple of seconds. I'm still trying to find a repeatable case.
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wasd
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by wasd » Thu Oct 17, 2019 10:08 pm

Do you mind sharing the scene?
CPU Bidir (sometimes GPU Path) + Metropolis | Log Power | Core i5-4570

kintuX
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by kintuX » Fri Oct 18, 2019 1:15 am

Been often experiencing the same issue.With Path CPU too.
Specularity and something about normals at grazing angles. Even with black 0 or IOR 1, there's reflection. While back sides seem ok.
I think it's also been mentioned before, iirc, there's a limit to how low roughness can be set :?

i don't know if it's related, but there's also some strange "Color management" behavior in Blender... thinking of: "Color Ramp, or anything in Blender, is pixel managed. As a result, I believe the Color Ramp is taking the scene referred 0.0 to 1.0 range and clipping it, which is leading to the harsh cut transition from 1.0 scene referred onwards."

Anyways here's the scene
GlossyTrans_Issue.blend
(175.11 KiB) Downloaded 12 times
btw, issue goes away with solidify deformer (@ 0.000001) but that creates extra geo...

wasd
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by wasd » Fri Oct 18, 2019 9:06 am

kintuX wrote:
Fri Oct 18, 2019 1:15 am
Been often experiencing the same issue.With Path CPU too.
Specularity and something about normals at grazing angles. Even with black 0 or IOR 1, there's reflection. While back sides seem ok.
It's back sides which are not ok :)
CPU Bidir (sometimes GPU Path) + Metropolis | Log Power | Core i5-4570

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FarbigeWelt
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by FarbigeWelt » Fri Oct 18, 2019 10:17 am

Dade wrote:
Thu Oct 17, 2019 9:43 pm
FarbigeWelt wrote:
Thu Oct 17, 2019 11:47 am
openCL render issues: unknown pattern :!:
Strange, yet unseen pattern in sky render.png

Did someone else observe one of these effects too?
I have noticed this problem only sometime and only in the very first samples than disappears after a couple of seconds. I'm still trying to find a repeatable case.
I made an animation with my original scene. The pattern is visible for all frames and does not dilute completely even with 1500 samples.
The scene attached shows the pattern every time I render it.
wasd wrote:
Thu Oct 17, 2019 10:08 pm
Do you mind sharing the scene?
Personally I would not mind. But The Grove's license is limited to distributing pictures only. Textures and tree models are not allowed to be shared.

The following scene contains a tree made with Sapling Tree Gen standard add-on. The leaf is self made. It took me hours to digitalize from a good picture found with a common search engine.
I can freely share the following 'simple' self made scene. You are free to use, change and/or share it, but gratis only.
openCL Issues_Birch.7z
openCL Issues_Birch
(2.65 MiB) Downloaded 20 times
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

wasd
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by wasd » Fri Oct 18, 2019 11:07 am

FarbigeWelt wrote:
Fri Oct 18, 2019 10:17 am
The leaf is self made. It took me hours to digitalize from a good picture found with a common search engine.
That's a great leaf! Polygon count is a little too big for my taste. And it's doubled. You can use hals as many ;) And I think those leafs are a bit less flat when hanging on a branch.
That's a young tree with a young leaves. Young leaves are pretty glossy and uneven.
leaves.jpg
p.s. I can't really do anything with the scene, that's too much for my hardware, but it looks like the same problem as kintuX's.
CPU Bidir (sometimes GPU Path) + Metropolis | Log Power | Core i5-4570

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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by FarbigeWelt » Fri Oct 18, 2019 12:40 pm

wasd wrote:
Fri Oct 18, 2019 11:07 am

That's a great leaf! Polygon count is a little too big for my taste. And it's doubled. ... And I think those leafs are a bit less flat when hanging on a branch.
That's a young tree with a young leaves. Young leaves are pretty glossy and uneven. leaves.jpg

p.s. I can't really do anything with the scene, that's too much for my hardware, but it looks like the same problem as kintuX's.
Many thanks for your feedback!

You are right, the leaf is not finished yet. I have to think about how to get into the third dimension without adding much more vertices. Currently the leaf is made from three levels, whereas two are required for translucent material.

Oops. This is the reduced version of the scene. The original has a ‚few‘ leaves more what takes some time for zooming or moving on my system but the lag is still acceptable for me. Seems heavy depending on GPU (~350 € card should do it). Since I often use larger particle systems I am glad that Blender 2.80 supports GPU for this. The CPU is not up to date yet, I am waiting for Ryzen 3950 (16 cores plus hyper threading).

I did not try kintuX‘s scene. I just guessed, it is the same effect.
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

kintuX
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by kintuX » Fri Oct 18, 2019 2:15 pm

wasd wrote:
Fri Oct 18, 2019 9:06 am
kintuX wrote:
Fri Oct 18, 2019 1:15 am
Been often experiencing the same issue.With Path CPU too.
Specularity and something about normals at grazing angles. Even with black 0 or IOR 1, there's reflection. While back sides seem ok.
It's back sides which are not ok :)
Indeed. Thanks for correction.
And to further correct myself
I think it's also been mentioned before, iirc, there's a limit to how low roughness can be set
True, cuz that would make a surface specular and result would be as expected. But what I was observing happens with Roughness set to 1. Which still shows this highlights or "sun spots" as if surface is glossy, specular on the backsides.

Now, if there was a front/back side, double sided material defining option implemented, that would easily solve this problem...
... but there's only such an option for opacity.

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Dade
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Re: openCL render issues: unknown pattern, sporadic white particles with Matte translucent

Post by Dade » Tue Oct 22, 2019 10:04 am

FarbigeWelt wrote:
Fri Oct 18, 2019 10:17 am
I made an animation with my original scene. The pattern is visible for all frames and does not dilute completely even with 1500 samples.
The scene attached shows the pattern every time I render it.

openCL Issues_Birch.7z
Here, with this scene, happens only some time: this makes the problem very hard to investigated. It may be related to variance clamping, can you check if it happens when variance clamping is disabled ? And if CPU/GPU hybrid rendering is disabled ?
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