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colintheys
02-11-2004, 12:42 AM
Hi,

I'm doing some work for a music video and have been asked to track human forms out of live-action footage and apply various special effects to them.

I'm a brand new combustion user, so I'm a little worried about this. What would be the best way to go about pulling a human form out of a 2d image with very accurate edges? I was trying to use combustion's tracking feature to follow the edges of their bodies, but the program doesn't seem to do a very good job, as the points shift around, and the bezier curves don't automatically adjust or even change.

Any suggestions would be great. Where should I go looking for tutorials? Should I use a different program? Is there some sort of an edge tracking feature in combustion I just don't know about?

Thanks
-Colin THeys

Making the switch from 3d to 2d...

Jack Pfeiffer
02-11-2004, 07:58 AM
Hi...

If you want to REMOVE people -- The technique is called Rotoscoping, and describes the frame-by-frame removal of objects.

Yes, it can be done with Combustion, and you typically include paint tools (such as Clone and Reveal) to replace the removed object with the proper background.. In the end, the object is NOT THERE. Kinda like the flick "Invisible Man" was made..

You ask about TUTS, etc. See this post here for a full list:

http://www.cgtalk.com/showthread.php?s=&threadid=117176

regards
Jack
denmark

Chris
02-11-2004, 08:13 AM
& in terms of the tracker, it tracks points, not edges. So you could for example select a point on the end of a finger, & track the finger end. Combustions tracker is extremely good, the tracker tutorials on the CD's are well worth going through...

Rotoscoping is a very time consuming process, no two ways about it. However, theres nothing like going through video frame by frame in a dark cupboard to put hair on your chest :) Again, combustions G-Masks are wicked good for this kind of thing, the edge spline gradients can let you acheive feathered masking like nuthin else. So be rest assured youve got a good tool for the job, just dont expect it to be quick.

colintheys
02-12-2004, 06:55 AM
Hi,

Thanks for the help guys. Actualy, I'm not looking to remove the people from the frame, but rather I'm looking to lift the person into their own layer and individually color correct them, so that I could, for instance, make an entire person fade to yellow (or black and white). I was hoping to use the tracker to follow the person's edges (or simulate that through tracking points,) but I seem to be gathering that I'll basically have to hand pick the people out of the frames (or convince them to shoot the entire video against a green screen!) The problem with point tracking seems to be that, since this is a music video, the camera is always moving. So, while the edge on the person stays constant, the background is shifting behind them, which can be very confusing for the poor tracker. Plus, everyone is dancing all the time. :/ (Why can't it be a funeral procession music video?)

Well, if hand-selection one frame at a time grows chest hair, I will be able to star in the next mighty joe young movie by the end of this! Or get a job in a carpet store as a human shag-carpet sample. hehe

dg
02-15-2004, 11:16 PM
Well for that I think that the process will be the same as described by Jack, otherwise Motion Control comes to my mind.
You could also try Mokey from Imagineer Systems, I've tested their LE version and it works very well with broadcast reso, if this is your case you try to enter in contact with them because I think they have a license rent option, not too sure tho.

- http://www.imagineersystems.com/


Cheers,
dg

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