Blender Discussions

[caspardavidfriedrich]

I've tried a very simple scene of Suzanne moving swiftly across the screen.

I ticked Combined, Depth, World Coordinate and Velocity.

All the passes rendered out fine except the Velocity pass which was pure black.

I'm running the official version of Blender on Mojave.

Anyone experiencing a similar issue?

Thanks.

[bsavery]

Do you have motion blur on? 

[caspardavidfriedrich]

Hi Brian,

Thanks for your reply.

I have now turned motion blur on and indeed I now get a velocity pass but - why would I need to render out a velocity pass if I’ve rendered out motion blur in any case?

I thought the whole point of a velocity pass is to have much quicker renders - since rendering motion blur is normally expensive - and using the velocity pass later in a comp to get ‘cheaper' motion blur?

That’s certainly the case whenever I render out animations in Blender and want to control the amount fo motion blur later in the comp using the velocity pass in Nuke or Fusion.

Or do I misunderstand how RPR renders?

Thanks,

Konrad

[bsavery]

So it has to do with a bit with how blender give renderers data.  Blender gives you the data for the current frame.  If there is motion for the scene you have to query the scene twice (or multiple times) to get the motion data.  We don't get that data unless motion blur is turned on for obvious performance reasons. 

[caspardavidfriedrich]

Hi Brian, OK… so the vector/velocity pass is then not really an option for me… in fact I fail to see a use for it under any circumstance for compositing animation. Or am I missing something?

One pass that you've added which I really appreciate is the World Position.

BTW, I just want to thank you guys for continual development of RPR for Blender and Mac… it can’t be easy. Cheers.