2.5 Vector Blur Does not Work Correctly

Hi All,

Once again I thought I would give vector blur a try, I generally deem it too low quality to use for any final work. And once again it is producing render anomalies.

Consider this image. It seems that vector blur just gives up processing if it encounters an alpha space?

In this image, there is a white floor plane and the sky is white. When the arrow in motion crosses the horizon threshold, vector blur gives up an produces an unusable frame.

Is there anyway to make vector blur just be on all the time? Why would it quit processing its blur just because the ground plane runs out?


You could fix this with a cheat in composite. Send your image to a Separate RGBA node and connect its Alpha output to the Alpha input of a Set Alpha. Connect the vector blur node output to the Image plug on the Set Alpha.

@CD38: I did try out your suggestions, and even a few variations, but Vector Blur still can not handle the horizon line correctly. I even tried force feeding it a solid alpha instead. I tried making the arrow have it’s own Pass Index and processing only that part.

Quite disappointing, would you consider this a bug?

Here is another vector blur test I conducted. I created two silhouette objects in Blender. One is a TIFF image with an alpha channel. The other is SVG imported curve. Both silhouettes are people.

I set both objects to the same exact animation of spin along the Z-Axis, assume origin at floor.

There is still a problem with blurring an image mapped plane with an alpha when it encounters the horizon line of the floor. I did try moving the horizon line but the problem moves with it.