wrong motion blur from usd in cycles and reverting to the first frame when disabeling motion blur #118261

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Victor-Schroers · 2024-02-14T12:44:39+01:00

Victor-Schroers commented

2024-02-14 12:44:39 +01:00

System Information
Operating system: Windows-10-10.0.22631-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3070 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 551.23

Blender Version
Broken: version: 4.1.0 Beta, branch: blender-v4.1-release, commit date: 2024-02-12 20:16, hash: d45175c919f3
Worked: (newest version of Blender that worked as expected)

Short description of error
I was experimenting with hair curves that I exported from Houdini and noticed a few issues.
First of all Eevees motion blur appears to be correct and changing the shutter in the render properties changes the intensity of the mb as expected. Cycles on the other hand ignores the changes.
Image 1 shows the default look, Img. 2 shows the result with a lower shutter and velocity speed value. For comparison: Img. 3 is the expected result I get when I scale the speed down in Houdini.

Changine the velocity scale in the MeshSequenceCache has no effect. (Eevee and Cycles)

If you deactivate motion blur altogether, the first frame of the mesh sequence is used. In my case frame 72 even though I am trying to render frame 81. This is the case in Eevee and Cycles

Although a known missing feature, importing a custum or even a color attribute when using point is still impossible.

The Zip file includes the .usd file that I used and the blender setup. (The usd does not include the curveu and cd attribute, I tried that separately)

It would be lovely if you could use Blender to render hair exported from Houdini, for example.

Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]

**System Information** Operating system: Windows-10-10.0.22631-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3070 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 551.23 **Blender Version** Broken: version: 4.1.0 Beta, branch: blender-v4.1-release, commit date: 2024-02-12 20:16, hash: `d45175c919f3` Worked: (newest version of Blender that worked as expected) **Short description of error** I was experimenting with hair curves that I exported from Houdini and noticed a few issues. First of all Eevees motion blur appears to be correct and changing the _shutter_ in the render properties changes the intensity of the mb as expected. Cycles on the other hand ignores the changes. Image 1 shows the default look, Img. 2 shows the result with a lower shutter and velocity speed value. For comparison: Img. 3 is the expected result I get when I scale the speed down in Houdini. Changine the _velocity scale_ in the MeshSequenceCache has no effect. (Eevee and Cycles) If you deactivate motion blur altogether, the first frame of the mesh sequence is used. In my case frame 72 even though I am trying to render frame 81. This is the case in Eevee and Cycles Although a known missing feature, importing a custum or even a color attribute when using point is still impossible. The Zip file includes the .usd file that I used and the blender setup. (The usd does not include the curveu and cd attribute, I tried that separately) It would be lovely if you could use Blender to render hair exported from Houdini, for example. **Exact steps for others to reproduce the error** [Please describe the exact steps needed to reproduce the issue] [Based on the default startup or an attached .blend file (as simple as possible)]

Screenshot_noMotionBlur.png

2.5 MiB

Cycles_01_mb.png

1.8 MiB

Cycles_01_mb_onetenth.png

1.8 MiB

Cycles_03_mb_trailonetenth.png

2.1 MiB

Blender_Mb_Bug.zip

22 MiB

Screenshot_noAttributes.png

2.2 MiB