View Full Version : Real dilemma - Tracking a Matte with Combustion

08 August 2003, 08:12 PM
Hi all,

I'm trying to get my head around a problem, and was hoping someone will be able to help. I have used combusion quite a bit, I've tracked with paint and i have colour corrected, and I have composited layers of 3d as well, so I got some good idea of my whereabouts in Combustion.

The situation: I have a scene of a hand held camera shot of a long road, and i want to replace the background houses and trees with a matte that lines up with a certain point in the horizon of the shot.

Problem: I Dont really know how to approach this, I have tried to read up in the manual about stabilising, and tracking but am confused. The only way I can think this can be done, is to create a montage style thing that takes into account all of the edges at their extremes so that you get a huge picture of everything the camera sees and then paint ur matte over this, pop it into the background as a mask over the original footage and then render from the motion of the camera. But I dont know how to do this.

Hope someone can help.

09 September 2003, 09:11 AM
You can do one of two things in my opinion.

Either stabilize the shot or track multiple points on the horizon and add that motion to your matte.

At least that is how I would approach it.

Alan Bell

10 October 2003, 05:59 AM
Hi vfx, Hi Alan,

Just a crazy idea, probably will not work since I haven't tried it yet, but you could stabilize your clip, paint the matte, precompose, and precompose again, and then using the schematic view you could duplicate your stabilize node and link him between the stabilized comp and the final one, then go to the timeline and use a math operator "negate" on this duplicated stabilize node to bring back the camera shake to your scene. I know I'm crazy, but I'll test this here with some time, and if it works it will be awesome.

If find something I'll come back here or pm you both.

Good luck with your scene mate,
See you all later! :)

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