Vray
- Create velocity render element
- Uncheck "clamp"
Nuke
- Pipe the velocity pass into a grade with these settings:
- Black point: 0.5 (this is to remove the grey background)
- Black clamp: off (since motion vector contains both positive and negative data)
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- Using copy node, copy the R and G channels from the velocity pass to the forward u and forward v of the rgb beauty
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- pipe this into a vectorBlur node with these settings:
- uv channels: forward
- multiply: 0.5 (this equals 180 deg of the shutter)
- method: forward
- check use rgba.alpha (The alpha is necessary for the proper edging of the motion blur)
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The resulting node graph should look like this:
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