Quality control and quality assurance checks for LIDAR data continue to evolve as the industry identifies new ways to help ensure that data collections meet desired usage requirements. The U.S. Geological Survey (USGS) LIDAR Base Specification introduced a definition for spatial density distribution and regularity within LIDAR data. The requirement is that the spatial distribution of usable points shall be uniform and regular. LIDAR data by nature is not a gridded surface but a series of random points. To best approximate a uniform surface it is recommended that LIDAR collections should be planned in such a manner as to produce a first return point cloud that comes close to a regular lattice of points. Generally this means having equal downtrack and crosstrack nominal point spacing. This is important since without the requirement it is possible to satisfy the project density requirements, yet still have data that is inconsistent and contains holes, generally in the down track spacing direction due to vehicle movement, allowing for desired features to be missed, or only partially acquired.
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