Any idea if vray with 3ds Max produces the correct rpf velocity channels for using with Reel Motion Blur?
I've seen the steps needed for producing the correct velocity channel with mental ray in 3ds max, and the added steps required.
We need to use Vray as it has a stereoscopic setting that other render engines are missing, and can't use a stereoscopic plugin as we want to send the work onto an online render farm which wont support any of the 3rd party plugins.
As such we want to produce rpf files using vray (which will produce a split view for 3d) and also export the velocity channel which we can then use to add motion blur in after effects with the Reel Motion Blur plugin.
I answered you at techsupport but for the sake of general info:
1) By default the RPF exports ZXY in RGB instead of XYZ - if it worked would require a channel swap in a precomp.
2) The 3D channel support for RPF in AE has been deprecated for EXR support, and only the initial 11 ones (not velocity, part of 5 next one they added) were supported by the 3D channels thing back then.
3) The MV exported from Mental Ray are slightly different then from RPF or VRAY. RPF and VRAY provide "instant" velocity while Mental Ray provides "velocity" as motion to next frame (same as renderman except renderman I think is to previous frame - and don't get me started on this as this is subject to interpretation, in Softimage for example you reverse what I just said - why you see the Scale X and Y sliders in our MV tools). For Motion Blur either will do, but for doing Twixtor from MV for example only the Mental Ray method would work.
4) In general the most common tech support issue is people don't turn off color management for such file (i.e preserve rgb in the advanced tab), which is not good as it remaps the color values which have a meaning. I always suggest to render a static scene and see that it all comes out as 0.5,0.5 for red and green channel.