Dynamic Particle Hair Failing to be Visible in Optix Device Cycles Render on Linux if Motion Blur Is Enabled #87269

Closed
opened 2021-04-07 16:06:44 +02:00 by MrP · 8 comments

System Information
Operating system: OpenSUSE Leap 15.2
Graphics card: NVIDIA RTX 2070, NVIDIA RTX 3070
NVIDIA Driver: 460.67-lp152.36.1-x86_64 (NVIDIA Proprietary)
CUDA: 11.2, 10.1
Renderer: Optix (only GPU, not CPU)

Blender Version
Broken: 2.92.0, 2.91.0, 2.93.0-24d71acd864b-linux64
Worked: none

Short description of error
In some scenarios, whilst using Optix Render Devices on Linux, some Dynamic Particle Hair systems will fail to render if Motion Blur is enabled in the Render panel. This appears to only happen on Linux, as I can't recreate the issue using the same scene files in Windows 10 (various builds).

Exact steps for others to reproduce the error
I've failed to come up with a tiny reproducible scene that I am able to share (my project is 8.2GB, and includes commercial and personal assets). The complexity of the scene seems to be a condition of this. These seem to be related factors:

  • Dynamic Particle Hair System. Does not seem to affect hair systems without Dynamics enabled.
  • Emitting from a separate scalp mesh, with Render Emitter disabled
  • Armature modifier on the emitter object, rigify rig in action
  • Character moving fast. Not impossibly fast, the physics cache remains fine and this displays fine in the viewport
  • When rendering using Optix Device (reproduced with both an RTX 2070 and an RTX 3070, though seems more easy to trigger on an RTX 3070), the hair will not render at all. The rest of the scene appears to be intact. Only occurs with Optix, I have not reproduced this using CUDA.
  • Occurs on multiple versions of Blender, including latest Alpha
  • Occurs with multiple versions of the CUDA toolkit
  • Does not occur using the same scene files transferred to Windows 10, tested with numerous versions of Blender.
  • No errors appear in System Console
  • No errors if --debug-cycles invoked (attached)
  • Clearing /var/tmp/OptixCache_$username/ does not resolve
  • Render Sample Count does not impact, nor does tile size.
  • Hair rendering as 3D Curves or Rounded Ribbons does not appear to impact this.
  • Never occurs in Viewport, even with Rendered Mode (not surprising, as I believe Motion Blur is never enabled in the viewport)
  • Clean installation of OpenSUSE does not resolve issue

Workarounds

  • Disable Motion Blur. Undesirable.
  • Render using CUDA rather than Optix. Slower, but plausible.
  • On the Emitter Object, untick Motion Blur > Deformation. Acceptable as a work around.

debugcycles.txt

This render is the issue. The scalp dynamic hair has failed to render whilst motion blur is enabled. Generating no errors or failures. Note that non-dynamic systems (facial hair, eyebrows) render
01.MotionBlurOn.png

This is the same frame, with motion blur disabled. The scalp dynamic hair appears in final render without issue
02.MotionBlurOff.png

This is the same frame, with motion blur enabled but object deformation disabled for the scalp. Renders all hair systems without issue.
03.MotionBlurOnDeformationOff.png

Apologies again for being unable to provide a sample blend file reproducing this. Happy to provide any further information that may be required.

**System Information** Operating system: OpenSUSE Leap 15.2 Graphics card: NVIDIA RTX 2070, NVIDIA RTX 3070 NVIDIA Driver: 460.67-lp152.36.1-x86_64 (NVIDIA Proprietary) CUDA: 11.2, 10.1 Renderer: Optix (only GPU, not CPU) **Blender Version** Broken: 2.92.0, 2.91.0, 2.93.0-24d71acd864b-linux64 Worked: none **Short description of error** In some scenarios, whilst using Optix Render Devices on Linux, some Dynamic Particle Hair systems will fail to render if Motion Blur is enabled in the Render panel. This appears to only happen on Linux, as I can't recreate the issue using the same scene files in Windows 10 (various builds). **Exact steps for others to reproduce the error** I've failed to come up with a tiny reproducible scene that I am able to share (my project is 8.2GB, and includes commercial and personal assets). The complexity of the scene seems to be a condition of this. These seem to be related factors: - Dynamic Particle Hair System. Does not seem to affect hair systems without Dynamics enabled. - Emitting from a separate scalp mesh, with Render Emitter disabled - Armature modifier on the emitter object, rigify rig in action - Character moving fast. Not impossibly fast, the physics cache remains fine and this displays fine in the viewport - When rendering using Optix Device (reproduced with both an RTX 2070 and an RTX 3070, though seems more easy to trigger on an RTX 3070), the hair will not render at all. The rest of the scene appears to be intact. Only occurs with Optix, I have not reproduced this using CUDA. - Occurs on multiple versions of Blender, including latest Alpha - Occurs with multiple versions of the CUDA toolkit - Does not occur using the same scene files transferred to Windows 10, tested with numerous versions of Blender. - No errors appear in System Console - No errors if --debug-cycles invoked (attached) - Clearing /var/tmp/OptixCache_$username/ does not resolve - Render Sample Count does not impact, nor does tile size. - Hair rendering as 3D Curves or Rounded Ribbons does not appear to impact this. - Never occurs in Viewport, even with Rendered Mode (not surprising, as I believe Motion Blur is never enabled in the viewport) - Clean installation of OpenSUSE does not resolve issue **Workarounds** - Disable Motion Blur. Undesirable. - Render using CUDA rather than Optix. Slower, but plausible. - On the Emitter Object, untick Motion Blur > Deformation. Acceptable as a work around. [debugcycles.txt](https://archive.blender.org/developer/F9922927/debugcycles.txt) This render is the issue. The scalp dynamic hair has failed to render whilst motion blur is enabled. Generating no errors or failures. Note that non-dynamic systems (facial hair, eyebrows) render ![01.MotionBlurOn.png](https://archive.blender.org/developer/F9922930/01.MotionBlurOn.png) This is the same frame, with motion blur disabled. The scalp dynamic hair appears in final render without issue ![02.MotionBlurOff.png](https://archive.blender.org/developer/F9922932/02.MotionBlurOff.png) This is the same frame, with motion blur enabled but object deformation disabled for the scalp. Renders all hair systems without issue. ![03.MotionBlurOnDeformationOff.png](https://archive.blender.org/developer/F9922933/03.MotionBlurOnDeformationOff.png) Apologies again for being unable to provide a sample blend file reproducing this. Happy to provide any further information that may be required.
Author

Added subscriber: @thechode

Added subscriber: @thechode
Author

I've retested this in just released Blender 2.93, and same issue occurring

I've retested this in just released Blender 2.93, and same issue occurring
Member

Added subscriber: @lichtwerk

Added subscriber: @lichtwerk
Member

Changed status from 'Needs Triage' to: 'Needs User Info'

Changed status from 'Needs Triage' to: 'Needs User Info'
Member

Thx for the report!

Since this only occurs in complex files:

  • can you try removing unrelated stuff, commercial assets etc. one by one and share the most minimalistic .blend that still shows this issue?

(this just has a higher chance of coming up with a reproducable case compared to devs building up a complex scene until they run into this -- it also makes sure we are all on the same page).

Thx for the report! Since this only occurs in complex files: - can you try removing unrelated stuff, commercial assets etc. one by one and share the most minimalistic .blend that still shows this issue? (this just has a higher chance of coming up with a reproducable case compared to devs building up a complex scene until they run into this -- it also makes sure we are all on the same page).
Author

This is embarassing, but I just fired up my scene again in the last tested version of Blender (2.93) and issue is no longer occurring. I can only assume that this was resolved in an NVIDIA driver update along the way (currently have 470.57.02-lp152.43.1-x86_64 installed).

Tested in a couple of different versions of Blender, can no longer recreate. So this appears to be resolved.

This is embarassing, but I just fired up my scene again in the last tested version of Blender (2.93) and issue is no longer occurring. I can only assume that this was resolved in an NVIDIA driver update along the way (currently have 470.57.02-lp152.43.1-x86_64 installed). Tested in a couple of different versions of Blender, can no longer recreate. So this appears to be resolved.
Member

Changed status from 'Needs User Info' to: 'Archived'

Changed status from 'Needs User Info' to: 'Archived'
Member

Oki, glad to hear!

Oki, glad to hear!
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Reference: blender/blender#87269
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