Motion Tracking Question
computer magic - Motion Tracking Question-
OK I wanted to put bullet hole effects in to my movie, where they hit the wall. But, my camera is not tripod so it moves, and when the camera moves, the bullet holes move along with the camera and don't stay in the right spot. I have heard of motion tracking and think that is what I need.
Can someone explain what motion tracking is, how it works, how it can be done, etc... Or if it is NOT motion tracking, can you explain motion tracking anyway, and then tell me what I need to do to make this effect work? Thanks...
Danny
Hi,
Motion tracking is the process where you specify one or more points in your image, for the computer to track.
This way, the software will be able to compensate for the cameramovement, and link movement of other effects layers to the cameramovement.
You'd have to have at least one, and better 2 points in the images that the computer could track. They often put ping-pong balls in a scene to use when motion-tracking later, but a clear point with some contrast will do.
After Effects has a motion tracker but it's no good. Commotion has a very famous motion tracker, and so does Combustion.
It's impossible to go in depth here on the complete process that you'd have to go through. Look into either of the programs, there will be manuals or help-files that explain more...
HTH
Barend
The amount of Points needed depends on what data you want/need.
1 Point : obviously gives you only a position referal
2 Points : gives you the ability to track Position, Rotation and Scaling (while scaling is available only for ONE axis (with or height)
3 Points : gives you Position, Rotation and scaling.
All this refers to 2d-tracking only of course. if you need 3d-data to be reverse-engineered out of 2d-footage there need a LOT more points to be involved.
After Effect's motion tracking isn't bad at all. I've managed to do some pretty seamless effects with it.
------------------
Low Budget Productions
http://www3.sympatico.ca/raoul23
All times are ET (US)