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Filling an area between the paths of moving objects

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Mehdi Rafeie
Filling an area between the paths of moving objects
on Aug 12, 2015 at 4:31:38 am

Hi guys,

I have a project I am undertaking and would appreciate if I could get some help or direction in finding a solution.

The project is based on a large number of video files of particles passing through a bifurcation. I need to find a way to automatically process the videos to trace the paths of these particles. The paths can be represented as lines. Then I need to fill in the area between the outermost lines to show the entire area the pathways are covering.

So far I have been able to detect the individual particles using the Auto-trace tool from the Layer menu; however, I need to draw a line depicting the path itself which I am not sure how to go about. Then I need to fill in the entire area that the paths have covered.

I have attached a video to show the basic idea of what I am going after. I did it manually by drawing the area with a pen tool but because of the large number of video files I am looking for a way to do this automatically.

Very much appreciate your help, thanks.


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Kalle Kannisto
Re: Filling an area between the paths of moving objects
on Aug 12, 2015 at 1:15:25 pm

I'll toss an idea for your consideration:

IF the backgrounds are perfectly stationery so that only the particles move and the clips are relatively short, you might be able to do this with a difference blend and CC Time Blend. The idea is to use a still image grabbed from the beginning of the footage and blend the current frame with it in difference blending mode, maximize the result so that you get clear dots. Then Time Blend this for the entire length of the footage. If everything goes as per theory, the result would be the actual tracks of the particles as lines which you can then overlay on the footage itself-


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Mehdi Rafeie
Re: Filling an area between the paths of moving objects
on Aug 13, 2015 at 7:42:03 am

Thank you very much Kalle, your nice idea solved my problem. I uploaded the result here.


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Kalle Kannisto
Re: Filling an area between the paths of moving objects
on Aug 13, 2015 at 8:00:53 am

Great - that works nicely indeed!


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