I was sitting on my porch the other day when I noticed a twin engine prop plan flying relatively low (1500’?) overhead. I’d seen it earlier flying a low circle and assumed he was looking at something on the ground. This time he flew almost directly overhead and I could see a large black square on the bottom of the fuselage. I could also see what I assume was green laser “sparkling” from the center of the box. No beam or anything (it was mid-day) just a green dot. So, what was he doing and how does it work? Using a laser to aim a camera? Nothing blew up so I guess no drone strike was in the works.
It may have been LIDAR.
Probably lidar. Planes fly over areas and shoot rapid pulses of laser to measure changes in terrain height by calculating the time it takes the laser to bounce back. This data gets made into a point cloud and a digital elevation model.
Scientists, foresters, government agencies, etc. use this data for all sorts of land-use decisions. The government does a lot of this work and makes it available for free. You can download their data and use open-source software like Quantum GIS to play with it.
That make sense. We were impacted by Superstorm Sandy and flood maps are being revised (although I thought this was already completed). How wide of a swath can be covered in one sweep?
This kind of data is also used in conjunction with modeling software to plan cell phone base station locations.