Motion Blur causes random black surfaces on rigged models #41116

New Issue

Sebastian Kreutz · 2014-07-18T14:19:50+02:00

Sebastian Kreutz commented

2014-07-18 14:19:50 +02:00

System Information
Windows 7 Ultimate, Intel Core i7-4470, tested against the following GPUs:

nvidia geforce GTX 660 (CUDA)
nvidia geforce GTX 760 (CUDA)
ATi Radeon HD 7800 (CPU render)

Blender Version
Broken: 2.71
Worked: 2.70a

Short description of error
We are experiencing surfaces on rigged models to become black in the final render (Cycles) regardless of their material configuration when Motion Blur is enabled. This occurs seemingly random, as the sub-objects affected have the same material as other parts of the same rigged model. Depending on where we position the camera track, these objects sometimes appear black and sometimes with their appropriate material color. It appears as if only the diffuse color is affected, since depending on the material color, specular reflections are getting different tints. When motion blur is disabled, the colors render appropriately. The issue only occurs in the final render, the viewport preview render is not affected.
This issue was not present in 2.70a, so I would assume the issue is related to the new deformation motion blur introduced in 2.71: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.71/Cycles

Exact steps for others to reproduce the error

Open the .blend test file (http://files.frame6.de/test/debugscene.zip) with Blender 2.71, it contains a camera track with the affected model
Render the first frame in Cycles with the existing presets: You notice that part of the roboter arm appears black

Now turn off motion blur in the render settings and notice how the roboter arm is fully orange as it should be

**System Information** Windows 7 Ultimate, Intel Core i7-4470, tested against the following GPUs: - nvidia geforce GTX 660 (CUDA) - nvidia geforce GTX 760 (CUDA) - ATi Radeon HD 7800 (CPU render) **Blender Version** Broken: 2.71 Worked: 2.70a **Short description of error** We are experiencing surfaces on rigged models to become black in the final render (Cycles) regardless of their material configuration when Motion Blur is enabled. This occurs seemingly random, as the sub-objects affected have the same material as other parts of the same rigged model. Depending on where we position the camera track, these objects sometimes appear black and sometimes with their appropriate material color. It appears as if only the diffuse color is affected, since depending on the material color, specular reflections are getting different tints. When motion blur is disabled, the colors render appropriately. The issue only occurs in the final render, the viewport preview render is not affected. This issue was not present in 2.70a, so I would assume the issue is related to the new deformation motion blur introduced in 2.71: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.71/Cycles ![mblur_off.png](https://archive.blender.org/developer/F98394/mblur_off.png) ![mblur_on.png](https://archive.blender.org/developer/F98395/mblur_on.png) **Exact steps for others to reproduce the error** - Open the .blend test file (http://files.frame6.de/test/debugscene.zip) with Blender 2.71, it contains a camera track with the affected model - Render the first frame in Cycles with the existing presets: You notice that part of the roboter arm appears black # Now turn off motion blur in the render settings and notice how the roboter arm is fully orange as it should be

Sebastian Kreutz commented

2014-07-18 14:19:50 +02:00

Changed status to: 'Open'

Sebastian Kreutz commented

2014-07-18 14:19:50 +02:00

Added subscriber: @argosy_ops

Sergey Sharybin self-assigned this 2014-07-18 15:26:21 +02:00

Sergey Sharybin commented

2014-07-18 15:26:32 +02:00

Will have a look later.

Lukas Tönne commented

2014-07-18 17:46:15 +02:00

Added subscriber: @LukasTonne

Lukas Tönne commented

2014-07-18 17:46:15 +02:00

I can't say what is going wrong here, but here is a reduced test file that should make further investigation easier:
intro_debug5.blend

All objects removed, except the broken mesh + armature
Camera and light replaced by default objects
Motion blur turned off on both the object and the scene (the error still persists!)
Armature modifier disabled
Added a cube mesh in the same object data, somehow this gets created with inverted normals (i did not do that myself)

So it might actually be a normals problem of some kind ...

I can't say what is going wrong here, but here is a reduced test file that should make further investigation easier: [intro_debug5.blend](https://archive.blender.org/developer/F98428/intro_debug5.blend) * All objects removed, except the broken mesh + armature * Camera and light replaced by default objects * Motion blur turned off on both the object and the scene (the error still persists!) * Armature modifier disabled * Added a cube mesh in the same object data, somehow this gets created with inverted normals (i did not do that myself) So it might actually be a normals problem of some kind ...

Rob Waite commented

2014-07-18 19:57:47 +02:00

Added subscriber: @RJW

Rob Waite commented

2014-07-18 19:57:47 +02:00

I noticed that the part of the arm in question has a negative Z-scale. When I apply scale (CTL+A), it renders OK with or without motion blur.

Sebastian Kreutz commented

2014-07-18 20:12:21 +02:00

@RJW thanks for helping narrow this down. I didn't take a look at scales and was wondering why it only happens to that part of the arm.
I can confirm that everything renders as it should once I apply the scale.

@RJW thanks for helping narrow this down. I didn't take a look at scales and was wondering why it only happens to that part of the arm. I can confirm that everything renders as it should once I apply the scale.

Brecht Van Lommel commented

2014-07-19 14:41:12 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2014-07-19 14:41:12 +02:00

Motion blur has to decompose the matrix into translate/scale/rotation, interpolate, and then recompose it. Probably somewhere along the way the scale gets flipped.

blender-admin commented

2014-07-23 14:01:35 +02:00

This issue was referenced by eb8f85d8be

This issue was referenced by eb8f85d8be8a14cbb8e97ba3b91c02cfd0ebbe42

Sergey Sharybin commented

2014-07-23 14:02:45 +02:00

Changed status from 'Open' to: 'Resolved'

Sergey Sharybin closed this issue

2014-07-23 14:02:45 +02:00

Sergey Sharybin commented

2014-07-23 14:02:45 +02:00

Closed by commit eb8f85d8be.

Closed by commit eb8f85d8be.

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Motion Blur causes random black surfaces on rigged models #41116

Now turn off motion blur in the render settings and notice how the roboter arm is fully orange as it should be