Multi-echo airborne laser point cloud surface crack extraction method for mining subsidence area under loess gully terrain

The invention discloses a multi-echo airborne laser point cloud earth surface crack extraction method for a mining subsidence area under a loess gully terrain, belongs to the technical field of unmanned aerial vehicle measurement, and mainly solves the problem that earth surface cracks caused by underground mining are affected by vegetation coverage under the loess gully terrain condition. And general photogrammetry and remote sensing images are difficult to extract. The method comprises the following steps: acquiring multi-echo airborne laser point cloud data of a mining subsidence area by acquiring ground data, setting a safe flight height on a DEM path profile, planning a route in a simulated ground flight mode, and acquiring and resolving point cloud data; according to the loess gully region multi-echo data distribution rule and the multi-echo characteristic, a regular grid is set, and point cloud filtering is carried out in an echo data separation mode; and using a Canny edge detection algorithm to extra