Maniphest T94425

Volume artifacts when transparent interfaces are in front, and issues with Min Light and Transparency Bounces
Closed, ResolvedBUG

Assigned To
Germano Cavalcante (mano-wii)
Authored By
Fernando Alcala (TriFractal)
Dec 28 2021, 12:53 AM
Tags
  • BF Blender
  • Render & Cycles
Subscribers
Fernando Alcala (TriFractal)
Germano Cavalcante (mano-wii)
HEYPictures (HEYPictures)
Richard Antalik (ISS)
Tokens
"The World Burns" token, awarded by HEYPictures.

Description

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.68

Blender Version
Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-12-25 21:08, hash: rBdd3a72f275b3

Short description of error
Dark voxels in a volume (size is directly related to volume resolution) appear when Min Light Bounces or Min Transparency Bounces are set too low when some kind of transparent interface is in front.
Also, they appear to get darker when bounces are increased.

Exact steps for others to reproduce the error


Place an object with a transparency, glass with a non-1.0 color, or Principled BSDF with transmission in front of a volume (add mesh Suzanne → add volume empty → mesh to volume modifier).
T93246 (Brecht triaged it as high priority) and T94394 are of this issue.

With one interface to go through, only 1 is needed for the Min Bounces. But when multiple interfaces are in front, more Bounces are needed (obviously). But as bounces increase, the dark voxels get darker until they are instantly gone.

With both Min Light and Transparency Bounces set to 0


With Light 0 going from Transparency 1 up to 7:








With Transparency 0 going from Light 1 to 7:








Both Light and Transparency 7


When Transparency is clear, adding even a clear glass object will then make it blocky again. No amount of Transparency can clear that.


Just set Light to 1 and it's fixed.

Then in this case, Light and Tran are 0, but it's clear through the glass?


And this is a single object with modeled geometry instead of different objects.

Related Objects

Mentioned In
T94394: Volume blocky through glas
Mentioned Here
rB75a051a6abb8: Fix T93246: Cycles wrong volume shading after transparent surface
T93246: OpenVDB volume artifacts with transparent plane in front
T94394: Volume blocky through glas

Event Timeline

Fernando Alcala (TriFractal) created this task.Dec 28 2021, 12:53 AM
Fernando Alcala (TriFractal) added a project: Render & Cycles.
Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Needs Information from Developers.Dec 29 2021, 7:55 PM
Germano Cavalcante (mano-wii) added a subscriber: Germano Cavalcante (mano-wii).

Since the issue can be worked around by editing Min Light Bounces or Min Transparency Bounces, I wonder if this is a limitation and not a bug.

HEYPictures (HEYPictures) added a subscriber: HEYPictures (HEYPictures).Dec 30 2021, 12:45 PM

Yea, but it is not intended to look that way and theoretically bumping the min bounces up does increase render times.

Fernando Alcala (TriFractal) mentioned this in T94394: Volume blocky through glas.Feb 2 2022, 4:26 AM
Fernando Alcala (TriFractal) added a comment.Feb 3 2022, 7:27 AM

Showing how smoke resolution relates to block size.

Richard Antalik (ISS) changed the task status from Needs Information from Developers to Confirmed.Feb 3 2022, 9:00 AM
Richard Antalik (ISS) merged a task: T94394: Volume blocky through glas.
Richard Antalik (ISS) added a subscriber: Richard Antalik (ISS).
Brecht Van Lommel (brecht) changed the subtype of this task from "Report" to "Bug".Feb 4 2022, 7:18 PM
HEYPictures (HEYPictures) awarded a token.Feb 4 2022, 8:28 PM
Fernando Alcala (TriFractal) added a comment.Mon, Jan 16, 12:57 AM

Resolved with the fix from May rB75a051a6abb86310496ada3b7f1a86bb9c7402bc.

Germano Cavalcante (mano-wii) closed this task as Resolved.Mon, Jan 16, 4:38 PM
Germano Cavalcante (mano-wii) claimed this task.

Thanks for the feedback @Fernando Alcala (TriFractal), I can confirm that the dark voxels are gone.