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View Full Version : how to use a velocity pass as a black and white pass


CGOrange
06-16-2009, 04:29 PM
Hey,
I have a velocity pass out of maya using the lm_2DMV_v2 shader.
When looking at the frame its all yellow. I applied it in after effects as a real smart motion blur vector and it works fine...
but
what I really want is a pass that shows the motion, where the faster the object is, that would be white and the non moving part would be white. Is there a way in after effects to convert my volocity pass to show this?

Thanks

israelyang
07-10-2009, 10:24 PM
yup you can.
The pass may look all yellow to you but it's not if there's any motion in your 3d file. The color may look green or red depending on how much movement there is.
To do what you want, you need to create a color layer, and pick the color from the motion vector pass where you know there is absolutely no movement. Now do a 'difference' of these 2 layers ( the color layer and the vector layer). The result of the difference would now tell you which pixels are moving and the more movement there is, the more different the color would be from the color layer. Now you can just monochrome the result and use level or curves to magnify the result.

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07-10-2009, 10:24 PM
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