Motion blur lost when rendering multiple copies of an alembic #90970

New Issue

Robert Rioux · 2021-08-26T16:43:57+02:00

Robert Rioux commented

2021-08-26 16:43:57 +02:00

System Information
Operating system: macOS-10.15.7-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro Vega 64 OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.10.18

Blender Version
Broken: version: 2.93.3, branch: master, commit date: 2021-08-17 18:30, hash: 8b80d19f36
Worked: Don't know

Short description of error
I imported the alembic from #90806 in an empty scene. Added a light. It renders in Cycles with motion blur. If I import a second version of the same alembic, or duplicate it, sometimes I lose MB on all of them or sometimes some of them.

Exact steps for others to reproduce the error

I wanted to send some blend file bit they are too big. Also, I wonder why that happens has the alembic is a cached file so it shouldn't take any space in the blend file but for every copies of the alembic I import in my file, the blend file gets and extra 10 megs. So to reproduce, just importe multiple copies of the abc file or duplicate it. Turn on MB of course.

This bug report is derived from #90806

**System Information** Operating system: macOS-10.15.7-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon Pro Vega 64 OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.10.18 **Blender Version** Broken: version: 2.93.3, branch: master, commit date: 2021-08-17 18:30, hash: `8b80d19f36` Worked: Don't know **Short description of error** I imported the alembic from #90806 in an empty scene. Added a light. It renders in Cycles with motion blur. If I import a second version of the same alembic, or duplicate it, sometimes I lose MB on all of them or sometimes some of them. **Exact steps for others to reproduce the error** I wanted to send some blend file bit they are too big. Also, I wonder why that happens has the alembic is a cached file so it shouldn't take any space in the blend file but for every copies of the alembic I import in my file, the blend file gets and extra 10 megs. So to reproduce, just importe multiple copies of the abc file or duplicate it. Turn on MB of course. This bug report is derived from #90806 ![5guys.jpg](https://archive.blender.org/developer/F10328605/5guys.jpg)

Robert Rioux commented

2021-08-26 16:43:57 +02:00

Added subscriber: @Funnybob

Philipp Oeser commented

2021-08-27 12:44:55 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-08-27 12:44:55 +02:00

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

Philipp Oeser commented

2021-08-27 12:44:55 +02:00

Cannot reproduce here.

Please try uploading again (zipped) that should still be fine with that one .abc from #90806 and as many duplicates as it takes to show this bug.
Also would be nice which frames fail for you (if framenumber makes a difference at all)

Cannot reproduce here. Please try uploading again (zipped) that should still be fine with that one .abc from #90806 and as many duplicates as it takes to show this bug. Also would be nice which frames fail for you (if framenumber makes a difference at all)

Robert Rioux commented

2021-08-27 16:13:31 +02:00

Here we go. Frame 61. Can you get the alembic from #90806 as it's about 400 megs? If not I can upload it if the system will allow me.

threeGuys.blend.zip

Here we go. Frame 61. Can you get the alembic from #90806 as it's about 400 megs? If not I can upload it if the system will allow me. ![ThreeGuys.jpg](https://archive.blender.org/developer/F10336582/ThreeGuys.jpg) [threeGuys.blend.zip](https://archive.blender.org/developer/F10336581/threeGuys.blend.zip)

Philipp Oeser commented

2021-09-16 10:40:58 +02:00

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

Philipp Oeser commented

2021-09-16 10:45:16 +02:00

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

Philipp Oeser commented

2021-09-16 10:45:16 +02:00

OK, can confirm now.

Kévin Dietrich commented

2021-10-05 05:04:36 +02:00

Added subscriber: @kevindietrich

Kévin Dietrich commented

2021-10-05 05:04:36 +02:00

Changed status from 'Confirmed' to: 'Archived'

Kévin Dietrich closed this issue

2021-10-05 05:04:36 +02:00

Kévin Dietrich commented

2021-10-05 05:04:36 +02:00

This happens because the other two meshes in the example file have "auto smooth" turned on, which causes some faces to be split for usage in Cycles. The split is different for each frames, so the topology differs and motion blur is deactivated. Thanks for the report, but this is not a bug per se. At least, duplicating the object (with Ctrl+D) does not turn on auto smooth.

This happens because the other two meshes in the example file have "auto smooth" turned on, which causes some faces to be split for usage in Cycles. The split is different for each frames, so the topology differs and motion blur is deactivated. Thanks for the report, but this is not a bug per se. At least, duplicating the object (with `Ctrl+D`) does not turn on auto smooth.

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Motion blur lost when rendering multiple copies of an alembic #90970