Extractor Module

Extractor has been released in version 1.7 and we have been asked for some guidance in establishing the planar and squaring parameters. These setting can be picky and tweaking may be required but here are some helpful concepts/ideas:

o First if the data is not sub meter then the planar filter quite likely will not do a very good job identifying planes.

o Make sure you are using a height filter and that the point filter that is used to build a ground surface is properly defined. The default is 2, and 8.

o Make sure the point spacing is set to the spacing of the data you are using the filter on.

o Despite the unit declaration on the property page for the planar filter (default is feet), if the units of the LiDAR data differ such as meters and the projection is not defined, the system cannot convert the values in the property page and the point spacing parameter would still be improperly defined.

o Make sure the minimum height parameter is properly defined for the dataset. The previous unit discussion would apply here too.

o If you are having trouble in overlap areas, some vendors will place overlap points on special classes such as overlap points (class 12). Remove these from the point filter (Define Points button). Often the overlap points are points that do not calibrate well with the neighboring points and will prevent points from fitting into planes.

o The filtering in residential areas and urban areas will require different configurations of the filter with slopes values that accommodate the high rise buildings.

QCoherent