It's a Blur

When working on our bauhuas project Steamed, we were having some issues with the way Maya handles motion blur (as has every Maya user at one time or another). I noticed the "keep motion vectors" option in 2D blur, had a cool idea for our production pipeline -- we would render everything without motion blur, then do a second pass where we re-rendered the same scenes but with all surface shaders, no lighting, and keep motion vectors. Finally, we would use the motion data from the blur pass and apply it to our high-quality renders. This way we would also have the flexibility to adjust the blur on a scene by scene basis.

This seemed like a wonderful idea at the time, until we hit a snag -- I couldn't get it to work, and from the Maya documentation it didn't seem possible. The blur2d tool that Maya provides for this process, besides having boneheaded file naming constraints, did not seem to provide this feature. Additionally, we ended up in such a time crunch on that project that there was no way we could go back through and fine-tune blur shot-by-shot. So we abandonded that approach.

Well, I was just trolling CG talk and discovered I was right -- you can indeed render a fast, untextured version of your scene w/Maya software to store the motion vectors, and then apply them to another file -- like a high-res one, or even one rendered in Mental Ray... :)

The reason why I doubted it could work -- turns out you need to use command-line flags that are undocumented in the Maya help files. They also aren't listed in the flags you get from calling "blur2d -help". Typical.

I'll test this out this week, as if it works I'm going to make it part of my thesis pipeline. I also want to hook Marty Geren up with it for his thesis, as his 12 hour-per-frame renders don't have motion blur, and rerendering them would be prohibitive.

Only things to note:

1) It's 2D blur, not 3D -- but I think it generally looks as good or better, and definitely better than a generic blur applied in post.

2) Applying it will be a klugey process -- though if it works then I'll script it and am happy to share the fruits of my labors...