Vector Blur streaks in wrong direction #54537

New Issue

Jeducious · 2018-04-07T11:40:17+02:00

Jeducious commented

2018-04-07 11:40:17 +02:00

Short description of error
When using Vector Blur, the expected behaviour is that the streaking or blurring of the object being blurred should form a tail behind the object. Behind referring to the opposite direction of travel. But as the image below clearly shows, the blur is ahead of the object. The object in this frame is actually heading upwards and to the left. This is not expected in a still it makes one think the object if falling down and moving slightly to the right, which is incorrect. During animations, rather then enhance the illusion of movement, it actually distracts the viewer quite a lot.

Exact steps for others to reproduce the error
To reproduce the error, simply load this blend file, allow the animation to run in order to fill the cache and then render the current frame.
Vector_blur_not_working.blend

System info txt [system-info.txt](https://archive.blender.org/developer/F2620291/system-info.txt) **Short description of error** When using Vector Blur, the expected behaviour is that the streaking or blurring of the object being blurred should form a tail behind the object. Behind referring to the opposite direction of travel. But as the image below clearly shows, the blur is ahead of the object. The object in this frame is actually heading upwards and to the left. This is not expected in a still it makes one think the object if falling down and moving slightly to the right, which is incorrect. During animations, rather then enhance the illusion of movement, it actually distracts the viewer quite a lot. ![vector_blur_issue.png](https://archive.blender.org/developer/F2620259/vector_blur_issue.png) **Exact steps for others to reproduce the error** To reproduce the error, simply load this blend file, allow the animation to run in order to fill the cache and then render the current frame. [Vector_blur_not_working.blend](https://archive.blender.org/developer/F2620284/Vector_blur_not_working.blend)

Jeducious commented

2018-04-07 11:40:17 +02:00

Added subscriber: @JamesCrowther

Brecht Van Lommel commented

2018-04-07 14:40:01 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2018-04-07 14:40:01 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2018-04-07 14:40:01 +02:00

Brecht Van Lommel self-assigned this 2018-04-07 14:40:01 +02:00

Brecht Van Lommel commented

2018-04-07 14:40:01 +02:00

For vector blur to work well you need to connect the Depth pass to the Vector Blur Z, otherwise it can't properly detect if the sphere is in front of the plane or not.

If you do that, it will show blurring before and after the sphere, as would happen for typical real world cameras that take some time to open and close the shutter.

For vector blur to work well you need to connect the Depth pass to the Vector Blur Z, otherwise it can't properly detect if the sphere is in front of the plane or not. If you do that, it will show blurring before and after the sphere, as would happen for typical real world cameras that take some time to open and close the shutter.

Jeducious commented

2018-04-08 01:10:18 +02:00

Changed status from 'Archived' to: 'Open'

Jeducious reopened this issue

2018-04-08 01:10:18 +02:00

Jeducious commented

2018-04-08 01:10:18 +02:00

Hi Brecht,

              First, thanks so much for the fast reply, I've been testing as you suggested and with the depth pass connected to the Z socket this works as you said it should. However, there is no mention of this fact in the documentation and I think it would save others a lot of head scratching if the docs simply announced what you wrote above.

The problem is compounded by the fact that the vector blur seems to work without the z pass connected, that coupled with no explanation of if in the docs meant it wasn't obvious that the Z input was the issue. So I've set the status to open, hope the documentation edit will help others not fall over their feet like I did :)

Kind Regards

J

Hi Brecht, ``` First, thanks so much for the fast reply, I've been testing as you suggested and with the depth pass connected to the Z socket this works as you said it should. However, there is no mention of this fact in the documentation and I think it would save others a lot of head scratching if the docs simply announced what you wrote above. ``` The problem is compounded by the fact that the vector blur seems to work without the z pass connected, that coupled with no explanation of if in the docs meant it wasn't obvious that the Z input was the issue. So I've set the status to open, hope the documentation edit will help others not fall over their feet like I did :) Kind Regards J

Brecht Van Lommel commented

2018-04-08 08:11:38 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2018-04-08 08:11:38 +02:00

Brecht Van Lommel commented

2018-04-08 08:11:38 +02:00

Please leave it to developers to reopen tasks.

I've added some extra text to the docs now.

Please leave it to developers to reopen tasks. I've added some extra text to the docs now.

Aaron Carlisle commented

2018-04-09 19:27:23 +02:00