[JKCalhoun]

I'm imagining a navigation system by trying to pattern-match the earth terrain with a downward-facing camera from the plane.

A suitably large database of satellite photos covering various conditions, day, night might work for all cases but cloudy (when the plane is above/in the clouds).

[fbanon]

Already exists: https://en.wikipedia.org/wiki/TERCOM Since the 1950s!

[JKCalhoun]

Oh yeah, contour-matching. I remember this being touted with regard to U.S. cruise missiles in the 80's, 90's.

Guess radar + countour is more reliable than camera + imagery.

(I'll crawl back to the 1800's now.)

[maxden]

They've used that landing on Mars as well, Terrain Relative Navigation.