Filter cameras by chunk tie points

[stephan]

Hey guys,
I'm certain that there is a smart way to do this, and I have a feeling I had solved this once before but I can't find the code anymore... What I need to to define the reconstruction area of a chunk and remove all the cameras that are not relevant for that reconstruction area (in order to save that as a sub-chunk but not duplicate the cameras). Any ideas how to do this?
Cheers,
Stephan