Detecting Duplicate Points

Sometimes duplicate points can appear in a data set which can throw off point counts. A simple method of detecting and getting rid of these points is through the use of the Thin Points tool in TerraScan.

Thin Points Dialog

To get rid of the duplicate points, use the settings as in the figure above.  Use the ‘By density’ method and the Keep ‘Central point’ setting.  This will look at groups of points within the prescribed distance and keep the point closest to the center of that group.  The key to using this tool to eliminate only duplicate points, is the Distance and Dz settings.

The Distance and Dz value should be set equivalent to the Resolution specified in the Define Coordinate Setup dialog (See example below). The resolution of the data in this example is 1000 per meter. Therefore the smallest meaningful distance in this data is 0.001 meters. For this example, the value 0.001 should be used in both the Distance and DZ settings of the Thin Points dialog.

Define Coordinate Setup Dialog

 

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