New Motion Blur in EEVEE is not blending steps properly for camera motion #79595

New Issue

Cycles · 2020-08-06T17:26:56+02:00

Cycles commented

2020-08-06 17:26:56 +02:00

System Information
Operating system: Microsoft Windows 10 Pro
Graphics card: Nvidia GeForce GTX 1050
Processor: Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz, 3301 Mhz, 4 Core(s), 4 Logical Processor(s)

Blender Version
Broken: blender-2.91.0-2c317457cbf2-windows64
Worked: New in 2.90, didn't work in older builds of 2.90

Short description of error
When there is very high camera motion blur in EEVEE, a step value greater than 1 introduces noticeable steps which don't get properly blended. There is some post-process blur but not enough to fill the gaps. Changing Max Blur or Background Separation doesn't help.

Exact steps for others to reproduce the error
Start with default blend file
Go to frame 1 and rotate the camera so the default cube is at the left of the screen
Add a keyframe (of rotation)
Go to frame 5 and rotate the camera so the default cube is at the right of the screen
Add another rotation keyframe
Turn on motion blur with steps set to 4
Render a still image at frame 3
Notice stepping artifacts not being blended properly by the post-process motion blur.

**System Information** Operating system: Microsoft Windows 10 Pro Graphics card: Nvidia GeForce GTX 1050 Processor: Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz, 3301 Mhz, 4 Core(s), 4 Logical Processor(s) **Blender Version** Broken: blender-2.91.0-2c317457cbf2-windows64 Worked: New in 2.90, didn't work in older builds of 2.90 **Short description of error** When there is very high camera motion blur in EEVEE, a step value greater than 1 introduces noticeable steps which don't get properly blended. There is some post-process blur but not enough to fill the gaps. Changing Max Blur or Background Separation doesn't help. **Exact steps for others to reproduce the error** Start with default blend file Go to frame 1 and rotate the camera so the default cube is at the left of the screen Add a keyframe (of rotation) Go to frame 5 and rotate the camera so the default cube is at the right of the screen Add another rotation keyframe Turn on motion blur with steps set to 4 Render a still image at frame 3 Notice stepping artifacts not being blended properly by the post-process motion blur. ![motionblurissue.png](https://archive.blender.org/developer/F8752571/motionblurissue.png)

Cycles commented

2020-08-06 17:26:56 +02:00

Added subscriber: @Cycles

Germano Cavalcante commented

2020-08-07 16:54:27 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-08-07 16:54:27 +02:00

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

Germano Cavalcante commented

2020-08-07 16:54:27 +02:00

I cannot reproduce this with either the latest stable or current development versions of Blender.
This is the file I tested:
motion_bug.blend

Please try the latest daily build: https://builder.blender.org/download/

If the problem persists, please give us more clear instructions on how to reproduce it from scratch.

I cannot reproduce this with either the latest stable or current development versions of Blender. This is the file I tested: [motion_bug.blend](https://archive.blender.org/developer/F8755962/motion_bug.blend) Please try the latest daily build: https://builder.blender.org/download/ If the problem persists, please give us more clear instructions on how to reproduce it from scratch.

Cycles commented

2020-08-08 00:12:48 +02:00

I tried with the experimental builds of 2.91, and the problem didn't seem to be there at first. However, turning max blur to 0 with a non-zero step value caused motion blur to not have any effect whereas in 2.90 there would still be multiple steps, just not blended using post-process blur. This leads me to assume that time step blur doesn't work in 2.91.

Also, in the .blend file that was provided the steps value is set to 1 while it should be set to 4.

I tried with the experimental builds of 2.91, and the problem didn't seem to be there at first. However, turning max blur to 0 with a non-zero step value caused motion blur to not have any effect whereas in 2.90 there would still be multiple steps, just not blended using post-process blur. This leads me to assume that time step blur doesn't work in 2.91. Also, in the .blend file that was provided the steps value is set to 1 while it should be set to 4.

Germano Cavalcante commented

2020-08-14 05:03:56 +02:00

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

Germano Cavalcante commented

2020-08-15 01:34:01 +02:00

In #79595#992908, @Cycles wrote:
(...) turning max blur to 0 with a non-zero step value caused motion blur to not have any effect whereas in 2.90 there would still be multiple steps, just not blended using post-process blur. This leads me to assume that time step blur doesn't work in 2.91.

Also, in the .blend file that was provided the steps value is set to 1 while it should be set to 4.

This appears to be a description of other bugs.
The ideal would be to make other reports.

I can try to replicate the problem and make these other reports another day.
Then close this one as resolved.

> In #79595#992908, @Cycles wrote: > (...) turning max blur to 0 with a non-zero step value caused motion blur to not have any effect whereas in 2.90 there would still be multiple steps, just not blended using post-process blur. This leads me to assume that time step blur doesn't work in 2.91. > > Also, in the .blend file that was provided the steps value is set to 1 while it should be set to 4. This appears to be a description of other bugs. The ideal would be to make other reports. I can try to replicate the problem and make these other reports another day. Then close this one as resolved.

Cycles commented

2020-08-16 14:50:53 +02:00

After I made the comment about the time step blur I noticed the other motion blur issues had already been reported.

https://developer.blender.org/T79646
https://developer.blender.org/T79672

After I made the comment about the time step blur I noticed the other motion blur issues had already been reported. https://developer.blender.org/T79646 https://developer.blender.org/T79672

Germano Cavalcante commented

2020-08-17 23:57:43 +02:00

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

Germano Cavalcante closed this issue

2020-08-17 23:57:43 +02:00

Germano Cavalcante self-assigned this 2020-08-17 23:57:43 +02:00

Germano Cavalcante commented

2020-08-17 23:57:43 +02:00

Thanks for taking a look at the other reports.
I suppose this one can be closed then.

Thanks for taking a look at the other reports. I suppose this one can be closed then.

Cycles commented

2020-10-01 18:37:51 +02:00

Reproducible in newer versions of Blender

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New Motion Blur in EEVEE is not blending steps properly for camera motion #79595