(v2.82+, CYCLES) Rendering with motion blur enabled causing unexpected, broken-looking result on specific frames #77102

New Issue

Kash Barr · 2020-05-27T08:17:57+02:00

Kash Barr commented

2020-05-27 08:17:57 +02:00

System Information
Operating system: MacOS 10.14.6
Graphics card: Intel Iris Pro 1536 MB{F8557214}

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-03-12 05:06, hash: 375c7dc4ca
Broken: 2.83 (sub 17), branch: master, commit date: 2020-05-15 17:29, hash: e5ace51295
Worked: v2.80 Beta branch: blender 2.7, commit date: 2019-02-08 04:22, hash: 46ac288a93

Issue:
(Cycles) Rendering with Motion Blur enabled in the Render Properties Tab causes unexpected, broken-looking result. Starting on frame 17, the final render will either display as simple "glitch"-looking image (flat grey and purple jagged shapes), or Blender may abruptly crash while rendering frame 17. If Motion Blur is toggled off, the final render yields the expected result.
motionBlurIssue.blend
Exact steps for others to reproduce the error

Open motionBlurIssue.blend in v2.82. Viewport should display model of a purple cassette tape.
Ensure Motion Blur is enabled in Render Properties Tab.
Render animation frames 16-20, format: FFmpeg video, container type: MPEG-4
Observe that starting on frame 17, the resulting render is "glitchy" broken-looking image inconsistent with contents of the 3d viewport.
4a. Disable motion blur and repeat steps 3 & 4 to observe expected results consistent with 3D viewport.

Thank you. The attached file is one section of a longer animation. This issue is occurring on multiple frames throughout the duration of the animation only when motion blur is enabled. The rate at which rendering the animation in this file results in a Blender crash, for me, is about 40%.

Attaching screenshot of "broken" frame 17 render result:

**System Information** Operating system: MacOS 10.14.6 Graphics card: Intel Iris Pro 1536 MB{[F8557214](https://archive.blender.org/developer/F8557214/motionBlurIssue.blend)} **Blender Version** Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-03-12 05:06, hash: 375c7dc4ca Broken: 2.83 (sub 17), branch: master, commit date: 2020-05-15 17:29, hash: e5ace51295 Worked: v2.80 Beta branch: blender 2.7, commit date: 2019-02-08 04:22, hash: 46ac288a9306 Issue: (Cycles) Rendering with Motion Blur enabled in the Render Properties Tab causes unexpected, broken-looking result. Starting on frame 17, the final render will either display as simple "glitch"-looking image (flat grey and purple jagged shapes), or Blender may abruptly crash while rendering frame 17. If Motion Blur is toggled off, the final render yields the expected result. [motionBlurIssue.blend](https://archive.blender.org/developer/F8557228/motionBlurIssue.blend) **Exact steps for others to reproduce the error** 1. Open motionBlurIssue.blend in v2.82. Viewport should display model of a purple cassette tape. 2. Ensure Motion Blur is enabled in Render Properties Tab. 3. Render animation frames 16-20, format: FFmpeg video, container type: MPEG-4 4. Observe that starting on frame 17, the resulting render is "glitchy" broken-looking image inconsistent with contents of the 3d viewport. 4a. Disable motion blur and repeat steps 3 & 4 to observe expected results consistent with 3D viewport. Thank you. The attached file is one section of a longer animation. This issue is occurring on multiple frames throughout the duration of the animation only when motion blur is enabled. The rate at which rendering the animation in this file results in a Blender crash, for me, is about 40%. Attaching screenshot of "broken" frame 17 render result: ![frame17.png](https://archive.blender.org/developer/F8557237/frame17.png)

Kash Barr commented

2020-05-27 08:17:57 +02:00

Added subscriber: @sikkapox

Alaska commented

2020-05-27 12:30:38 +02:00

Added subscriber: @Alaska

Alaska commented

2020-05-27 12:30:38 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Alaska commented

2020-05-27 12:30:38 +02:00

I am able to reproduce the issue on Linux-5.4.0-7629-generic-x86_64-with-debian-bullseye when rendering with a CPU (Ryzen 9 3900X) or a GPU GTX 1050Ti (CUDA) with Blender 2.90 eb5422828a (2020-05-26 20:02) . OptiX (Cycles_Optix_Test=1) does not show these issues.

I am able to reproduce the issue on Linux-5.4.0-7629-generic-x86_64-with-debian-bullseye when rendering with a CPU (Ryzen 9 3900X) or a GPU GTX 1050Ti (CUDA) with Blender 2.90 `eb5422828a` (2020-05-26 20:02) . OptiX (Cycles_Optix_Test=1) does not show these issues.

Alaska commented

2020-05-27 12:35:21 +02:00

Seems to be similar to #75441 as an object changes it's scale from something to 0 on frame 17. I will leave the decision up to the developers and other moderators on whether these issues are similar enough to merge.

Alaska commented

2020-05-27 12:37:50 +02:00

Actually, doing more investigation. I'm 95% confident these are the same issue. Merging the tasks.

Alaska commented

2020-05-27 12:38:08 +02:00

Closed as duplicate of #75441

Alaska closed this issue

2020-05-27 12:38:08 +02:00

Alaska commented

2020-05-27 13:15:22 +02:00

@sikkapox as a work around in the meantime, you can hide the objects you no longer want on frame 17 rather than scaling it to 0. This can be done by keyframing this option:

You will need to do this for each individual object, not just the empty that's used to control the scale of the object.

@sikkapox as a work around in the meantime, you can hide the objects you no longer want on frame 17 rather than scaling it to 0. This can be done by keyframing this option: ![Capture.PNG](https://archive.blender.org/developer/F8557664/Capture.PNG) You will need to do this for each individual object, not just the empty that's used to control the scale of the object.

Kash Barr commented

2020-05-27 22:19:26 +02:00

Thanks @Alaska will give your solution a shot.

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(v2.82+, CYCLES) Rendering with motion blur enabled causing unexpected, broken-looking result on specific frames #77102