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Video Gogh advanced stroke direction/speed

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martin lorenz
Video Gogh advanced stroke direction/speed
on Jul 4, 2011 at 9:38:27 am

I just tested out Video Gogh and learned about the Alt Direction Src and Alt Motion Src using the tutorials found at the revision site.
I'm working with a 3d tracked video which is now repainted via Gogh.
Getting the motion vectors out of my rebuilt 3d scene worked just fine. I was able to use the data as Alt Motion Src and (with a 180° hue shift added) also as Direction Map.

However my understanding is not profound yet so I was hoping that someone could give me the answer to the following question:
How would the maps have to look for the strokes to come out of the center and move towards the edges and simultaniousley be slow in the center and speed up towards the edges?
here is an image of how it should look:

i tried out different sets of gradients (center->outward and radial ones) with differnet colors but i couldnt get the desired result.
Another thing: If only a direction map is connected the strokes still move, and if only a motion map is connected the strokes still have various directions. why?
Should they not get just a direction if only the direction map is connected and then start moving if a motion map is added?

Some advice by a pro with more insight than i have would be much appreciated! :)

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Pierre Jasmin
Re: Video Gogh advanced stroke direction/speed
on Jul 4, 2011 at 9:33:50 pm

You saw the Direction Map section in the documentation (for the orientation part)?

If you want the brush to be oriented to follow the motion, one simple way if available to you would be to use to render a second render pass with the lm2dmv shader set to SmoothKit target (I believe it's also in the mental ray shader provided with Maya and Softimage) and use that pass direct as direction map. Not clear how you do that with other renderer then mental ray.

If you are trying to build ramps manually, note that 0.5 0.5 is no motion, so you can composite through a radial ramp some of that to scale the motion vectors so they are slower in the center and faster outward.

There is a more advanced tutorial for using SmoothKit Directional with Splines to make your own direction maps....

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