Camera tracking proposal

When making longer drone movies, track spots who where in the first frame are likely not available later in the movie. So for this typical kind of movies, it be handy to be able to tell starting from which start to end frames it is usefull.

Also for a lot of objects it might be handy to optionally provide manual estimated floor-height of the tracked object, from trak start frame, so the drone-tracked objects could be used as floor level (even if its a top of a tree, or house).