Motion Blur bug?

[werticus]

Object motion blur is 'on' in the object properties of the purple car on the left with default samples and duration. The cars wheels have motion blur on also, but with more object samples to get a proper circle effect. The car is part of an xref scene and the object blur is turned on in the external scene.
The camera is moving backward at the same speed as the car.
In the main scene, camera motion blur is turned on. (in the camera and in the render dialogue)

The blur showing up in the render does not seem to respect relative motion with the camera? It looks as you would expect it to look if the camera was not moving, when in fact it is?

I would only expect the wheels to have noticeable motion blur in this shot. Is this a bug with xref's or vray? Is it user error?

Please also note that: the bus has no blur.

I have the whole thing rendered out in draft quality on you tube also but I can only show that to chaos group.

[werticus]

We are running latest vray 3.60.04 and 2018.4

[werticus]

I tried importing the cars instead of xref, and the problem is still there.

[Zdravko.Keremidchiev]

Do you have velocity information for the car in the Velocity render element? What sort of shader have you used for the wheel? It will be helpful if you could send us the car and camera part of the scene so we could investigate further.

[werticus]

Here is the velocity: I will export the car and camera and email those over.
I don't really know how to 'read' this but the bus and cars on this side of the road are moving at the same speed so i would expect the same colours on them.

[werticus]

Not able to solve this?

[Zdravko.Keremidchiev]

The issue was caused by discrepancy in the Moblur duration values for the bus and the car. You will get a more detailed e-mail from us.

[werticus]

Thanks, all sorted now - User error is me expecting the motion blur duration to be a multiplier.