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Flickering reflections in surfaces and how to get rid of them?
happens constantly in certain reflective surfaces.
 
Nothing animated at all. I will send you the file.
 
Quote
thrimanakatha wrote:
Hello ssjenforcer,
I downloaded your scene and checked. At first it rendered black, so I removed the bitmap nodes and increased the hdr value to 1. Rendered with high clamp values and ray bounces. The GI flickering is there but not intense as like yours. Something is wrong with GI bounce inside transparent objects with Centileo.
I will check this model into other renders.
but I think I had the issue even with no transparent objects, when I had disabled the helmet in render view. Unless I forgot to make the render light red.

I do think you're right about it being global illumination.
Edited: ssjenforcer - Mar 30, 2022 18:07
 

(this is a GIF file, click on the image; if not played download the attachment.).
You can see the GI flicker in the right cube, reflection in the left sphere.
One hdr and a sunlight lit the scene. Left sphere has no thickness, right one has thickness applied.
Iteration value 8.


Iteration =16

All other centileo parameters are default.



No glass, max iter = 16.
Edited: thrimanakatha - Mar 31, 2022 01:47
 
Quote
thrimanakatha wrote:

(this is a GIF file, if not played download the attachment.).
You can see the GI flicker in the right cube, reflection in the left sphere.
I hdr and a sunlight lit the scene. Left sphere has no thickness, right one has thickness applied.
Iteration value 8.


Iteration =16

All other centileo parameters are default.
Yea I can see it.
 
Even with 32 iteration the gi flicker is prominent. Did some test with placing the object inside a cube, lighted with a single area light. There wasn't any noticeable gi flicker. But the scene took 4 min to render with default settings at 640x360 res.
 
Administrator  Posts: 797
Mar 31, 2022 08:23
thrimanakatha, can you send me this scene file with HDR please?
CentiLeo Chat: https://t.me/centileochat
 
I emailed the scene file.
 
Administrator  Posts: 797
Apr 2, 2022 22:51
Thanks for files to thrimanakatha, ssjenforcer
Working to fix the issue. At the moment I have found that if the object is tesselated (more polygons) more the artifact goes away. For example adding subdiv removes the artifact. But I need to fix it without this workaround.
CentiLeo Chat: https://t.me/centileochat
 
Quote
Kirgman wrote:
Thanks for files to thrimanakatha , ssjenforcer
Working to fix the issue. At the moment I have found that if the object is tesselated (more polygons) more the artifact goes away. For example adding subdiv removes the artifact. But I need to fix it without this workaround.
when you say adding Subdivision do you mean specifically subdividing the mesh polygons or adding a Subdivision surface? Or both?

I don't suppose increasing the phong angle helps to fix it if there is a phong tag?
Edited: ssjenforcer - Apr 2, 2022 23:06
 
@Kirgman,
Fixing the issue inside the code is future proof. It is not possible to add subdivisions always, especially in architectural rendering. Interior walls and roof may contain lesser polygons and it may not be perfectly arranged, sometimes with boolean and with ngons.
I am testing other renders also, so far they have no gi issues.
 
Administrator  Posts: 797
Apr 3, 2022 22:05
I want to fix the issue in the new coming release, this shouldn't work like that. It can be either an internal ray epsilon computation failure. Or it can be related to smooth normals that we have per vertex because when we increase subdivision and smoothness the stupid artifact goes away. Funny thing, but I hope to fix that soon :)
CentiLeo Chat: https://t.me/centileochat
 
Quote
Kirgman wrote:
I want to fix the issue in the new coming release, this shouldn't work like that. It can be either an internal ray epsilon computation failure. Or it can be related to smooth normals that we have per vertex because when we increase subdivision and smoothness the stupid artifact goes away. Funny thing, but I hope to fix that soon
Hmm yea that makes sense now.
I have a scene with cloth clothing on characters and the only flickering I had like before was a scarf on someone and it was the only cloth I didn't put into a subdivision surface.
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