Tracking foreground movement for background for composite
by Justin Silverman
on
Jul 5, 2008 at 6:28:15 pm
Hi All,
I'm trying to create a composite of a green screened foreground object with camera movement and a still image for the background. I got the keying all worked out, but I want to track the movement of the foreground object to the background but not have it move right in step with the foreground object so to give it some perspective. Currently I'm using a stabilize node to track the foreground and have it setup to match the movement for the background. This does provide the movement for the background image, but it's moving in step with the foreground. Is there a way to limit the stabilizing node or is there a better solution to this?
Re: Tracking foreground movement for background for composite by Michael Mench on Jul 5, 2008 at 6:58:24 pm
Did you place any tracking points on the green screen? If you did, just put a tracker on that spot and then use that data on a spot on the still and match move.
Re: Tracking foreground movement for background for composite by Justin Silverman on Jul 5, 2008 at 8:01:45 pm
Hey Michael,
Hah, that's so simple yet absolutely brilliant! Now I just need a couple of high contrast points on my green screen that I can set the trackers to (as they really can't get a handle on anything on the screen right now) and still be able to remove later on with a simple rotoscope.
Re: Tracking foreground movement for background for composite by Michael Mench on Jul 5, 2008 at 8:38:18 pm
The problem of course will be to pick a point on the replacement that is roughly the same distance from the point you will place the subject. Else your perspective will be off. There IS a way to add an expression to the motion of the matchmove data to offset the motion. I just don't know it, though can simply find out for you if needed.
