I am creating a video in which a person is walking and holding a picture frame. Within the frame a separate story is being told; the footage is mapped onto the frame using the "four corners" feature in Match Move. At the beginning of the video, the camera pans up from the ground until the entire frame is in the shot, then in the end the camera leaves the picture frame and pans up into the sky. I can match move all the motion in the middle of the video, but I'm having trouble figuring out how to deal with the beginning and end (where there aren't four corners to match). Thank you, and help is greatly appreciated.
An option is to do a 4pt Match Move from once you see all 4 points to when you don't see them again. Then select the Match Move Behavior and go up to Object, Convert to Keyframe. Then you can keyframe the video going in and then out and not have to worry about the middle because the behavior took care of that. Hope this made sense. Best of luck.
I'm always doing a bit of trial and error but as I understand that what the offset track option is for.
Set an in-point (composition in-point not match move) on the last frame where you have a particular tracker point still in frame. Now check the offset track option and reposition the tracker point to somewhere in the frame that stays longer visible and moves in the same way your picture frame moves (eg continue the top trackers by position to the bottom of picture frame) and track (you can do this for all points separately by unchecking the ones you don't want to track. Motion will now create points continuing you original track by using your new position as a reference.
If I'm wrong please somebody correct me :-)
Good explanation of the tracker functions can be found in a separate PDF from the Motion support site (sorry can't find the link)
Here is a tutorial I did on how to do an offset track in Motion. I guess it depends on the footage, but a one point offset track is easy to do. Just take a look at the tutorial. My concern is the rotation or skewing caused by a 4 point track not lining up with anything other then the picture frame because it is being hand held. Meaning, if the hands move the picture frame the background will be at different angles compared to the picture frame. It could be a lot of fun to take a look and see if it works. Take a look at the tutorial I linked to at the start of this paragraph.