Cost is not the only point he was making. The problem you need to solve is not just “Is there something?”, but also “What is it? And where is it going to move?”. LIDAR cannot do that. Or at least if you get LIDAR to do that, then you would have also been able to get it done with a camera, in which case you wouldn’t have needed LIDAR in the first place.
LIDAR certainly is the low hanging fruit when it comes to the firmer question though (i.e. what is there in my path right now).
LIDAR certainly is the low hanging fruit when it comes to the firmer question though (i.e. what is there in my path right now).