Christian, please also be aware that some of the techniques do not incorporate changes in scale of the tracked object. If you are working with aerial footage then this might be an important consideration.
I've recently worked on a similar problem, so you need any help, please feel free to email me (email address is given in my profile)
Thanks for the feedback ! I'm planning to use more robust and scale invariant features for this so this problem of different levels of zoom would be solved (at least to the limits of what can be done).
