Maniphest T93418

Shadow Terminator Geometry Offset causes artifacts for translucent shader (Cycles)
Closed, Resolved
Actions

Assigned To
Brecht Van Lommel (brecht)
Authored By
slowburn (slowburn)
Nov 26 2021, 11:33 PM
Tags
  • BF Blender
  • Render & Cycles
Subscribers
Alaska (Alaska)
Mikhail Matrosov (ktdfly)
slowburn (slowburn)

Description

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3060 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 496.13

Blender Version
Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-11-22 23:57, hash: rBd1a4e043bdb0
Worked: (newest version of Blender that worked as expected)

Short description of error
If object has smooth shading and Geometry Offset enabled, then shadows visible through the surface, due to translucent shader, appear broken up. The intensity of this effect depends on how irregular the shape is. In these examples there is a sphere casting a shadow on the other side of the object.


How it should look:

Exact steps for others to reproduce the error

  • Add a translucent shader to an object
  • Enable smooth shading and Geometry Offset
  • Add another object that would cast clear shadow on the surface of the first object

geo_offset_bug.blend878 KBDownload

Revisions and Commits

rC Cycles
D13468rC994fe98ab523 Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency
rB Blender
D13468rB4c8740a45217 Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency
D13468rBa92805bf24f5 Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency

Related Objects

Event Timeline

slowburn (slowburn) created this task.Nov 26 2021, 11:33 PM
Alaska (Alaska) changed the task status from Needs Triage to Confirmed.Nov 28 2021, 7:40 AM
Alaska (Alaska) added a project: Render & Cycles.
Alaska (Alaska) added subscribers: Mikhail Matrosov (ktdfly), Alaska (Alaska).

I can confirm the issue however I'm not entirely sure if this is a bug or an artifact that's expected of the geometry offset. @Mikhail Matrosov (ktdfly) are you able to comment on this?

Mikhail Matrosov (ktdfly) added a comment.Nov 29 2021, 11:51 AM

In general, this kind of artifacts is expected (saddle points on geometry, smooth normals are parallel and have a big enough angle from geometry normals), although I know how it can be improved for this specific case (looking from behind by using the translucent bsdf), so I'd call it a bug.

Mikhail Matrosov (ktdfly) mentioned this in D13468: Fix Shadow Terminator Geometry Offset artifacts for translucent shader (Cycles).Dec 4 2021, 11:13 PM
Alaska (Alaska) added a revision: D13468: Fix Shadow Terminator Geometry Offset artifacts for translucent shader (Cycles).Dec 4 2021, 11:35 PM
Brecht Van Lommel (brecht) closed this task as Resolved by committing rBa92805bf24f5: Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency.Dec 7 2021, 7:02 PM
Brecht Van Lommel (brecht) claimed this task.
Brecht Van Lommel (brecht) added a commit: rBa92805bf24f5: Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency.
Brecht Van Lommel (brecht) mentioned this in T93479: 3.0 Potential candidates for corrective releases.Jan 6 2022, 2:48 PM
Philipp Oeser (lichtwerk) added a commit: rB4c8740a45217: Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency.Jan 11 2022, 10:39 AM
Brecht Van Lommel (brecht) added a commit: rC994fe98ab523: Fix T93418: Cycles shadow terminator Geometry Offset artifacts with translucency.Jan 27 2022, 11:37 PM