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Oliver Navarro Schroeder avatar image
Oliver Navarro Schroeder asked ·

How do i render out motion vector passes from Arnold C4DTOA and use them in After Effects with the RSMB plugin?

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Sen Haerens avatar image
Sen Haerens answered ·

You have to use the motion vector shader and a custom AOV because the default motion vector AOV values are not normalized. RSMB expects float values between 0 and 1.0 in Red and Green.

  • Setup as above to disable motion blur in beauty
  • Arnold MV shader: disable RAW and set max. displace to same value as RSMB max. displace.

  • AE RSMB settings

Here is quick render (RSMB blur amount set to 8 - very exaggerated - should be 1 for conventional 180° camera shutter).

Demo Animation

Project file

Lastly, RSMB compared with native Arnold curved motion blur, much nicer. So, remember RSMB is not the real thing. ;-)

Arnold curved motion blur demo


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It's mean that we need to add this shader in all materials?

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Use the Arnold Custom AOV tag

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Interesting... Then I would have to group all objects of my scene to use the tag in case that the camera does move?

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Carlos Dordelly avatar image
Carlos Dordelly answered ·

Maybe it can works, in this tutorial this guy separate the FG from the BG: https://vimeo.com/33243611

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Sen Haerens avatar image
Sen Haerens answered ·

Maybe you can separate the FG from the BG and put RSMB only on the FG and then composite it back together. I guess your scene will never render correctly with RSMB, too many small, overlapping objects.

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Yes, maybe its too much overlapping objects. Will try to separate fg and bg. The reason i want to make rsmba work correctly is to reduce render costs on a render farm. Rendered motion blur takes easily double the render costs.

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Oliver Navarro Schroeder avatar image
Oliver Navarro Schroeder answered ·

Thanks @Sen Haerens. That is very helpful. Your approach gave me the best results so far.

However i still remain with an ugly smudge around fast moving objects. Its as if the mv blur data affects the areas around the moving object as well. But maybe its a result of the limitations of the curved motion blur that you pointed out.


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Oliver Navarro Schroeder avatar image
Oliver Navarro Schroeder answered ·

Hi @Carlos Dordelly, thanks for the outline. Yes that is the easy part, but these motion vector passes never give me correct results in After Effects using ReelSmartMotionBlur.

The "Ignore Motion Blur" option in the Diagnose / System Settings is new to me though. I've been using an instantaneous shutter, which has the same result as the "Ignore Motion Blur" option i assume.

There has to be some specific way how to deal with the mv passes inside AE - like adjusting the Blackpoint, max displacement, etc. I tried anything i could think of with no success.

So any further hints on how to correctly work with these files in ae/rsmb would be highly appreciated.


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Carlos Dordelly avatar image
Carlos Dordelly answered ·

Hi @Oliver Navarro Schroeder! You can do:

Turn on motion blur -> Add motion vector AOV -> Turn on "ignore motion blur" option in the system menu.

01:

02:

But I don't know how to use correctly inside After Effects with the RSMB plug in :/.


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