There might be times when there is a desire to create artificial (synthetic) points for holes or data gaps which exist within the LIDAR dataset. For example, lakes or wide rivers, where there are no LIDAR returns. TerraScan has a tool that will generate a grid of points to help fill in the missing data. It is very important to note that this tool will not make up missing information concerning the LIDAR data, it simply generates a grid of points for the area where there are not laser points. The option is located on the Check Coverage tool (TerraScan Project –> Tools -> Create Points for Holes).
If Create points for holes is enabled, points are created that fill “holes”, “almost hole” and “almost covered” areas in a uniform grid structure . The generated points are assigned the classes chosen for each of the area types. The elevation of the artificial points is set to be equal to the number of points found in the sampling area. The points are saved in TerraScan binary files which get the same name as the original block binary files. A project file with the name DENSITY.PRJ is created that references the binary files with the artificial point.
When using LAS v1.4 it is best to create synthetic classes, S1, S2 and S3 for example, so that the points are properly flagged as synthetic when imported into the laser project.