This is a neat archaeological tool
One thing that people have done for many centuries is make marks on rocks, usually straight incised markings. Quite often, these aren't visible until a LIDAR system images them and enhances them. LIDAR has always been expensive; an inexpensive system would let you pull tricks such as imaging drystone walls looking for Roman incised stone fragments, say.
Mooching about looking in drystone walls is actually a valuable archaeological technique; people really hate carrying stone about, so a drystone wall is always a good representative sample of what was lying about on the ground surface in the immediate vicinity. Drystone wallers are no respecters of culture; a lump of Roman altar is just a nicely-fitting rock to them and into the wall it goes; ditto a five thousand year old Neolithic quern. Being able to easily spot these would be useful.
Biting the hand that feeds IT
