[magicalhippo]

For a loitering drone I imagine dead reckoning would cause significant drift unless corrected by external input. GPS is great when it's available but can be jammed.

I was thinking along the lines of preprocessing satellite images to extract prominent features, then using modern image processing to try to match against the observed features.

A quite underconstrained problem in general, but if you have a decent idea of where you should be due to dead reckoning, then perhaps quite doable?