Hi everyone, I'm running into an issue with Karma when trying to render motion vectors. To get them working, I have to enable motion blur and disable image blur. However, when I do this, the object appears time-shifted, even though no actual blur is being applied to the image (which is what I'm aiming for).

I'm wondering why this happens. The view in Houdini GL looks fine, but when I switch to Karma, the object gets shifted. Is this behavior intentional, or am I missing something? Any insights would be greatly appreciated!

I have the same issue, did you solve it?

I don't use Karma, but this happens in Mantra as well so I assume it's the same reason

it's because when MB is on even with Image MB off it renders the geo at Shutter Open time
which is likely -.25 or something by default and therefore you will see everything shifted

try overriding the Shutter Open to 0 and see if it fixes things
I however don't know the reason why this is a thing and if anyone ever found it useful

ah thanks Thomas, that's exactly what I figured out. Problem now is, how do I apply the same motion blur to MtoA so that in comp, both exrs fit on top each other?

I have stuff rendered in Maya Arnold and others in Houdini Karma XPU. So naturally the shift in Karma is problematic in comp.

AhmedHindy
So naturally the shift in Karma is problematic in comp.

for renders with Image MB disabled subtract shutter:open value on your camera from shutter:open and shutter:close esseentially offsetting shutter:open to 0

so -0.25 to 25 will become 0 to 0.5 etc

that way those renders will not be shifted and should more or less align with your nonMB Arnold renders