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Diffuse materials glow in corners or small gaps when using Principled Shader in Cycles
Closed, ArchivedPublic

Description

System Information
Operating system: Linux Mint 19.2
Graphics card: 1080 Ti

Blender Version
Broken: 2.80, cycles

Short description of error

Diffuse materials glow in corners or small gaps when using Principled Shader. I am not sure it is bug or correct behavior, but issue is gone if color value (V from HSV) is decreased to 0.9, or Diffuse shader is used instead. Decreasing roughness and specular also helps but that will make totally different material.

Exact steps for others to reproduce the error
Here are image and blend file

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Details

Type
Bug

Event Timeline

Brecht Van Lommel (brecht) closed this task as Archived.Wed, Nov 6, 4:47 PM
Brecht Van Lommel (brecht) claimed this task.

Diffuse materials with reflectivity 1.0 are unrealistic, and this kind of glowing can actually be accurate for the given parameters.

Hm did I miss something - it has roughness 1.0, specular 0.5, metlaness 0.0 - where does reflectivity 1.0 come from?

It's the base color that has 1.0 for some channels.

Here's your original material with a diffuse of HSV 0.5, 0.5, 1.0:

And here's the same scene with diffuse HSV 0.5, 0.5, 0.8:

Ah so essentially pure color is bad to use - I should decrease V to make color little bit darker, thanks ;)