A project is ongoing to search the battlefields around the Ypres Salient to detect WW1 archeological sites using LIDAR technology. Perhaps you’re not familiar with the term LIDAR?
‘Lidar (also called LIDAR, LiDAR, and LADAR) is a surveying method that measures distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3-D representations of the target. The name lidar, now used as an acronym of light detection and ranging (sometimes light imaging, detection, and ranging), was originally a portmanteau of light and radar.’ From Wikipedia.