Cycles: Motion blur Artifacts and high render time with Metaball #111244

New Issue

erjiang · 2023-08-18T02:47:54+02:00

erjiang commented

2023-08-18 02:47:54 +02:00

System Information
Operating system: Ubuntu Linux 22.04 / Windows 10 64-bit
Graphics card: Nvidia GeForce RTX 3080

Blender Version
Broken: 3.60, 3.61, 3.62, 4.0.0-alpha+main.d0dcfb815964
Worked: unknown

Short Description
Activating motion blur in Cycles results in artifacts and higher render time for 2% of frames
Reproducible across Ubuntu/Windows, CPU/CUDA/OptiX.

Exact steps for others to reproduce the error

Open attached file "phoenix12-reprocase.blend"
Enable motion blur (should already be enabled)
Reduce transmission bounce
Render frame 189
Render frame 190 (takes significant time to render. Also notice Artifacts)

In the provided file, frames 74, 124, 179, 190 seem to have this problem. Turning off motion blur fixes the problem.

189	190

**System Information** Operating system: Ubuntu Linux 22.04 / Windows 10 64-bit Graphics card: Nvidia GeForce RTX 3080 **Blender Version** Broken: 3.60, 3.61, 3.62, 4.0.0-alpha+main.d0dcfb815964 Worked: unknown **Short Description** Activating motion blur in Cycles results in artifacts and higher render time for 2% of frames Reproducible across Ubuntu/Windows, CPU/CUDA/OptiX. **Exact steps for others to reproduce the error** - Open attached file "phoenix12-reprocase.blend" - Enable motion blur (should already be enabled) - Reduce transmission bounce - Render frame 189 - Render frame 190 (takes significant time to render. Also notice Artifacts) In the provided file, frames 74, 124, 179, 190 seem to have this problem. Turning off motion blur fixes the problem. |189 | 190 | |---|---| | ![image](https://projects.blender.org/attachments/a0d67b9a-0427-42cb-8025-41e62b2675ea) | ![image](https://projects.blender.org/attachments/03df3edf-73be-4694-b532-11a3c82df059) |

phoenix12-reprocase.blend

628 KiB

erjiang added the

labels 2023-08-18 02:47:54 +02:00

Pratik Borhade commented

2023-08-18 07:30:28 +02:00

Thanks for the report. Can confirm when motion blur is enabled.
Though I'm not sure why this is happening. Memory usage and GPU utilization was also moderate.

Thanks for the report. Can confirm when motion blur is enabled. Though I'm not sure why this is happening. Memory usage and GPU utilization was also moderate.

Pratik Borhade added

and removed

labels 2023-08-18 07:30:44 +02:00

Pratik Borhade commented

2023-08-18 07:42:57 +02:00

@erjiang , could you reduce the "transparent bounces" to smaller value?

Pratik Borhade added

Status

Needs Information from User

and removed

Status

Confirmed

labels 2023-08-18 07:43:06 +02:00

erjiang commented

2023-08-20 21:32:29 +02:00

could you reduce the "transparent bounces" to smaller value?

Looks like that's the issue. Reducing transparent bounces to 5 keeps the render time low, so that probably means the render was not hanging, just the UI was unresponsive.

> could you reduce the "transparent bounces" to smaller value? Looks like that's the issue. Reducing transparent bounces to 5 keeps the render time low, so that probably means the render was not hanging, just the UI was unresponsive.

Fernando Alcala commented

2023-08-21 06:31:05 +02:00

1080 Ti, Optix
Transmission bounces reduced to 2

Frame 189 renders in 47 seconds
Frame 190 renders in 1611 seconds (x34 greater)

While the cloud itself barely changes, other significant differences appear.

1080 Ti, Optix Transmission bounces reduced to 2 Frame 189 renders in 47 seconds Frame 190 renders in 1611 seconds (x34 greater) While the cloud itself barely changes, other significant differences appear.

2tran frame190 26m51s.png

2.1 MiB

2tran frame189 47s.png

2.1 MiB

Pratik Borhade commented

2023-08-21 12:30:44 +02:00

Yes, can confirm the difference in render.
Not sure about the reason this time. Forwarding to Cycles developers for further investigation

Yes, can confirm the difference in render. Not sure about the reason this time. Forwarding to Cycles developers for further investigation

Pratik Borhade added

Status

Needs Info from Developers

and removed

Status

Needs Information from User

labels 2023-08-21 12:30:54 +02:00

Pratik Borhade commented

2023-08-21 13:02:16 +02:00

@Fernando-Alcala , difference in render result seems to be due to the animation data of CloudRightMball.006 (removing keyframe/channels of it restores the result)
I'll close the report since the original report and the above, both are different problems.
@Fernando-Alcala , could you open a new report or want me to do that?

@Fernando-Alcala , difference in render result seems to be due to the animation data of `CloudRightMball.006` (removing keyframe/channels of it restores the result) I'll close the report since the original report and the above, both are different problems. @Fernando-Alcala , could you open a new report or want me to do that?

Pratik Borhade closed this issue

2023-08-21 13:02:19 +02:00

Blender Bot added

Status

Archived

and removed

Status

Needs Info from Developers

labels 2023-08-21 13:02:21 +02:00

Fernando Alcala commented

2023-08-22 07:07:19 +02:00

What should this new report be about exactly?

erjiang commented

2023-09-01 07:15:22 +02:00

@Fernando-Alcala @PratikPB2123 Is there a follow-up report related to this that I can follow? Thanks

Pratik Borhade changed title from ~~Motion blur causes rendering to hang on certain frames~~ to Cycles: Motion blur Artifacts and high render time with Metaball

2023-09-01 07:24:01 +02:00

Pratik Borhade reopened this issue

2023-09-01 07:30:07 +02:00

Blender Bot added

and removed

labels 2023-09-01 07:30:09 +02:00

Pratik Borhade added

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labels 2023-09-01 07:30:17 +02:00

Pratik Borhade commented

2023-09-01 07:30:34 +02:00

@brecht , can you check?

Brecht Van Lommel commented

2023-09-08 17:41:11 +02:00

This is a known limitation of motion blur and metaballs currently. The problem is that motion blur needs either a mesh with a fixed topology, or a velocity attribute. While it's possible to add such an attribute in principle, it's beyond the scope of a bug report and would require big changes in Blender.

This is a known limitation of motion blur and metaballs currently. The problem is that motion blur needs either a mesh with a fixed topology, or a `velocity` attribute. While it's possible to add such an attribute in principle, it's beyond the scope of a bug report and would require big changes in Blender.

Brecht Van Lommel added

and removed

labels 2023-09-08 17:41:19 +02:00

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