This is a ScanLook Velodyne scan from a boat of the train trestle drawbridge over the Tennessee River in Decatur, AL. You can see the wake of the boat in the river.
Light Detection and Ranging is used to detect and measure the distance of an object or surface from an optical source.
LiDAR differs from photogrammetry in that photogrammetry uses passive light and LiDAR employs an active laser system.
LiDAR yields an intensity with the XYZ data to provide a black and white-like image.