Instancing Geometry on Imported Alembic Particles produces extremely long render times when motion blur is enabled. #109185

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ben-webber · 2023-06-21T05:00:31+02:00

ben-webber commented

2023-06-21 05:00:31 +02:00

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 535.98

Blender Version
Broken: version: 3.5.1 Release Candidate, commit date: 2023-04-03 16:00, hash: ef7e83c7ff15
Worked: (newest version of Blender that worked as expected)

Short description of error
Instancing geometry on Imported animated Alembic Particles using geometry nodes produces extremely long render times when motion blur is enabled. Turning off motion blur or realizing instances reduces the render time back to its normal average length.

Exact steps for others to reproduce the error

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 535.98 **Blender Version** Broken: version: 3.5.1 Release Candidate, commit date: 2023-04-03 16:00, hash: `ef7e83c7ff15` Worked: (newest version of Blender that worked as expected) **Short description of error** Instancing geometry on Imported animated Alembic Particles using geometry nodes produces extremely long render times when motion blur is enabled. Turning off motion blur or realizing instances reduces the render time back to its normal average length. **Exact steps for others to reproduce the error**

ben-webber added the

labels 2023-06-21 05:00:32 +02:00

YimingWu commented

2023-06-21 05:04:23 +02:00

Hi @ben-webber , could you provide us a blend/alembic file that can replicate the issue? Thanks!

YimingWu added

Status

Needs Information from User

and removed

Status

Needs Triage

labels 2023-06-21 05:04:34 +02:00

ben-webber commented

2023-06-21 05:08:53 +02:00

Hi @ben-webber , could you provide us a blend/alembic file that can replicate the issue? Thanks!

Is there an upload limit? The alembic is about 150mb

> Hi @ben-webber , could you provide us a blend/alembic file that can replicate the issue? Thanks! Is there an upload limit? The alembic is about 150mb

YimingWu commented

2023-06-21 05:13:18 +02:00

@ben-webber Could you try trimming it down a bit? Or you could also use google drive or something.

ben-webber commented

2023-06-21 05:17:12 +02:00

Blender

test.blend

66 MiB

ben-webber commented

2023-06-21 05:18:55 +02:00

alembic is uploading to google drive

ben-webber commented

2023-06-21 05:20:10 +02:00

https://drive.google.com/file/d/1yuBvgwM2S4ATIdgaLDaQB238YelxGtB8/view?usp=sharing

Thomas Dinges added

Status

Needs Triage

and removed

Status

Needs Information from User

labels 2023-08-11 12:33:25 +02:00

Philipp Oeser commented

2024-01-02 15:30:06 +01:00

So the .abc provides a .velocities Property (checked with abcls), but still MB seems quite random and with long streaks -- which kind of explains the long rendertimes:

So the .abc provides a .velocities Property (checked with abcls), but still MB seems quite random and with long streaks -- which kind of explains the long rendertimes: ![image](/attachments/a9913788-3588-4c2b-846b-a043b2dda83b)

image.png

1.3 MiB

Philipp Oeser commented

2024-01-02 16:27:29 +01:00

So apparently the velocity vectors are not supposed to be transferred to instances (known limitation for now), but another possibility would be to render points directly (MB is supposed to work then).

Cant get this to work though, will check again tomorrow

So apparently the velocity vectors are not supposed to be transferred to instances (known limitation for now), but another possibility would be to render points directly (MB is supposed to work then). Cant get this to work though, will check again tomorrow

❤️ 1

Philipp Oeser commented

2024-01-03 13:18:14 +01:00

OK, so after some digging I can verify that

alembic can read .velocities (even on varying point count)
(in order to properly export .velocities from blender you have to set up a Geometry Nodetree storing a Named Attribute called "velocity" -- check on the Internet on how to do this, also see
128eb6cbe9)
HOWEVER: this is only supported for meshes for some reason, not points

I will quickly check if adding this is straightforward (if not this might get closed as a Known Limitation I am afraid)

OK, so after some digging I can verify that - alembic can read `.velocities` (even on varying point count) - (in order to properly export `.velocities` from blender you have to set up a Geometry Nodetree storing a Named Attribute called "velocity" -- check on the Internet on how to do this, also see 128eb6cbe928e58dfee1c64f340fd8d663134c26) - HOWEVER: this is only supported for meshes for some reason, not points I will quickly check if adding this is straightforward (if not this might get closed as a Known Limitation I am afraid)

Steffen Dünner commented

2024-01-03 13:28:52 +01:00

This is a very long standing issue and I guess @kevindietrich already invested a lot of work in this.
Maybe it would be best to contact him about this.

This is a **very** long standing issue and I guess @kevindietrich already invested a lot of work in this. Maybe it would be best to contact him about this.

Philipp Oeser commented

2024-01-03 13:50:09 +01:00

This is a very long standing issue and I guess @kevindietrich already invested a lot of work in this.
Maybe it would be best to contact him about this.

I dont mean transferring the velocities to instances, I will look into just reading the velocities for points (in order to render points directly)

> This is a **very** long standing issue and I guess @kevindietrich already invested a lot of work in this. > Maybe it would be best to contact him about this. I dont mean transferring the velocities to instances, I will look into just reading the velocities for points (in order to render points directly)

Steffen Dünner commented

2024-01-03 13:58:43 +01:00

I also didn't mean the transfer but only the import / export of velocity (or even arbitrary attributes) on points.

#95945 (comment)

I also didn't mean the transfer but only the import / export of velocity (or even arbitrary attributes) on points. https://projects.blender.org/blender/blender/issues/95945#issuecomment-150358

Philipp Oeser commented

2024-01-03 14:19:15 +01:00

So velocity wasnt that hard, not sure if this will be considered outside of https://archive.blender.org/developer/D11591
(can post a patch for this shortly)

So velocity wasnt that hard, not sure if this will be considered outside of https://archive.blender.org/developer/D11591 (can post a patch for this shortly) ![image](/attachments/ea838458-37bf-4e0a-acf7-ac21787b42f6)

image.png

1.1 MiB

❤️ 1

Philipp Oeser referenced this issue

2024-01-03 15:58:27 +01:00

Alembic: read velocities on Points #116749

Philipp Oeser commented

2024-01-03 15:59:45 +01:00

Patch is up in !116749

❤️ 1

Steffen Dünner commented

2024-01-03 16:11:50 +01:00

Beautiful. Finally some movement.
Does this mean, you can commit it already?

Beautiful. Finally some movement. Does this mean, you can commit it already? ![image](/attachments/ffd77eeb-c996-4ea3-a0dc-e49ea82a76a5)

image.png

5.7 KiB

Philipp Oeser referenced this issue from a commit

2024-01-04 09:25:37 +01:00

Alembic: read velocities on Points

Philipp Oeser commented

2024-01-04 09:35:11 +01:00

Committed 472cf44166 now, so velocities are now read for points, you can render them directly with Cycles (as mathematical spheres).

The lack of propagating these to instances is still here though, so motionblur for them (on changing pointcounts) is still unreliable/wrong and can have high rendertimes (because their motion boundingboxes can be very large).

@brecht : do we want to keep this as Known Limitation?

Committed 472cf44166aff98c0cf481cc063406be4b0aa79c now, so velocities are now read for points, you can render them directly with Cycles (as mathematical spheres). The lack of propagating these to instances is still here though, so motionblur for them (on changing pointcounts) is still unreliable/wrong and can have high rendertimes (because their motion boundingboxes can be very large). @brecht : do we want to keep this as Known Limitation?

Philipp Oeser added

and removed