Hasta La Motion!

I am finally trying to learn how to get different image passes from Maya working correctly in Nuke and I’m having a problem with feeding motion vectors into F_MotionBlur to get a correct blurring effect in post.

I rendered out a frame stack with both a 2D and 3D motion vector pass. F_MotionBlur actually does a damn good job of just taking on the motion estimation itself, but as soon as I plug in my motion vectors, I start to get weird results.

I first tried the 2D motion vectors. I am running my EXR read through a Copy node to move the motion vectors from their strangely named maya channel into RGB, and then pluggin that into the BgVec input of my F_MotionBlur node. This just gives me a little bit of ghosting as if it’s just sampling the frames around the current frame and overlaying them with varied alpha.

So next I tried copying the 3D vector pass into RGB and doing the same thing. This just makes a progress window pop up where the remaining time endlessly increases (currently at 5 hours remaining and 2% completion).

I’ve also tried copying the motion vector passes into the Motion channel instead of RGB and then plugging it in to BgVec which gives me the same results as the 2D vectors described above.

Any ideas what I’m doing wrong?