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Eevee - Volumetrics - Increase Shadow samples max to equal volume samples max
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Description

System Information
Operating system: Windows 10
Graphics card: GTX 1060

Blender Version
Broken: 2.80+

Issue

Properties Editor > Render Tab > Volumetrics

Right now the Eevee volumetric samples are capped to 256 volume samples max and 128 shadow samples max. With 128 shadow samples, regardless of normal render samples and volume samples maxed out, will almost always create strobing artifacts due to the lack of shadows samples unpaired to the raymarched volume samples when you move the camera with animation.

Example:
imgur.com/uPNpMo1

Solution

Upping the volume samples (optional) and shadow sample cap to double or the same level as volumetric samples reduces the prominence of this shadow raymarching issue.

File:
\\source\blender\makesrna\intern\rna_scene.c

Exact steps for others to reproduce the error

  1. Select cube, made a material
  2. Change material a principled volume with noise + high density (a color ramp to change noise edges will help also)
  3. Animate a camera movement with two frames, linear interpolation1
  4. Max out the volumetric samples in the render tab
  5. Render
  6. See strobing of shadows on render

Event Timeline

I have recompiled and experimented with this with up to 512 shadow samples (which helps reduce the raymarching artifacts) a lot. It's no permanent fix, but it's a good quick fix and requires only change to two lines of code.

I am new here, and have never committed to Blender before, and still don't know how as the process is.. not like Github or Gitlab, but if it's ultimately easy, I can commit the file for review to merge or.. go into a branch?

Jacques Lucke (JacquesLucke) claimed this task.

Some information on how to contribute a fix can be found here: https://wiki.blender.org/wiki/Process/Contributing_Code
Increasing the maximum amount of samples seems should be fine afaik. Maybe @Clément Foucault (fclem) knows about some limitation that I'm not aware of.

I'll close this, because this is not really a bug. It would be nice if you could submit the patch for review. If you need more help with that, feel free to contact me in https://blender.chat/.