Velocity vector is incorrect with Cycles. #41951

New Issue

A Giraud · 2014-09-25T16:49:45+02:00

A Giraud commented

2014-09-25 16:49:45 +02:00

System Information
Operating system : Windows 7 Enterprise + service pack 1
Graphics card : NVIDIA GeForce GTX 480

Blender Version
Broken: v2.72 (hash : eb464ee if it is useful)

Short description of error
When rendering the velocity vector in Cycles, some objects (in my case, the ground) that don't move aren't black, as they are supposed to be. When rendered with Blender Render, the problem disappears.

Exact steps for others to reproduce the error
In the blend file, run the animation once.
Select Cycles, render and see the velocity in the viewer node.
Do the same thing while selecting the Blender Render.

I added the blend file and two images for clarity.

Rendered with Blender Render.

Rendered with Cycles.

**System Information** Operating system : Windows 7 Enterprise + service pack 1 Graphics card : NVIDIA GeForce GTX 480 **Blender Version** Broken: v2.72 (hash : eb464ee if it is useful) **Short description of error** When rendering the velocity vector in Cycles, some objects (in my case, the ground) that don't move aren't black, as they are supposed to be. When rendered with Blender Render, the problem disappears. **Exact steps for others to reproduce the error** In the blend file, run the animation once. Select Cycles, render and see the velocity in the viewer node. Do the same thing while selecting the Blender Render. I added the blend file and two images for clarity. ![rendererSpeed.jpg](https://archive.blender.org/developer/F112409/rendererSpeed.jpg) Rendered with Blender Render. ![cyclesSpeed.jpg](https://archive.blender.org/developer/F112410/cyclesSpeed.jpg) Rendered with Cycles.

A Giraud commented

2014-09-25 16:49:45 +02:00

Changed status to: 'Open'

A Giraud commented

2014-09-25 16:49:45 +02:00

Added subscriber: @Yauda

Sergey Sharybin was assigned by Bastien Montagne

2014-09-25 17:06:22 +02:00

Brecht Van Lommel commented

2014-10-04 16:04:07 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2014-10-04 16:04:07 +02:00

There is no .blend file attached to this report?

Sergey Sharybin commented

2014-10-07 14:49:12 +02:00

There is no.

@Yauda, please attach .blend file which demonstrates the issue, otherwise we can't investigate your issue.

There is no. @Yauda, please attach .blend file which demonstrates the issue, otherwise we can't investigate your issue.

A Giraud commented

2014-10-07 16:08:06 +02:00

crashing_centerMass_speed.zip

here is the compressed file. Sorry, I was sure I had added it, but it was too big and the upload had failed.

[crashing_centerMass_speed.zip](https://archive.blender.org/developer/F115391/crashing_centerMass_speed.zip) here is the compressed file. Sorry, I was sure I had added it, but it was too big and the upload had failed.

Bastien Montagne commented

2014-10-14 08:34:04 +02:00

Added subscriber: @mont29

Sergey Sharybin commented

2014-10-21 13:09:16 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2014-10-21 13:09:16 +02:00

Sergey Sharybin commented

2014-10-21 13:09:16 +02:00

This is a precision issue, your plane has quite crazy scale. There are couple of workarounds:

Apply the scale of the plane
Use more round scale, like 95 or 100 for your case

In order to make Cycles work more reliable here we'll need to go with double precision, which would mean we'll drop consumer market GPUs which works nicely with single precision only.

This is a precision issue, your plane has quite crazy scale. There are couple of workarounds: - Apply the scale of the plane - Use more round scale, like 95 or 100 for your case In order to make Cycles work more reliable here we'll need to go with double precision, which would mean we'll drop consumer market GPUs which works nicely with single precision only.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Velocity vector is incorrect with Cycles. #41951