TerraScan’s Detect Wires routine runs on points that are loaded within TerraScan. This works well if the project area is small but it can become more complicated when trying to run the routine over a larger area. The following are just some of the options available when it comes to running the detect wires routine over a large project and they range from easiest to more complex.
Single Block of Data
Create a single block of data and load all the data into TerraScan at one time. Depending upon what version of TerraScan is being used (32 bit versus 64 bit) will determine the recommended number of points that can be loaded in TerraScan.
Once the data is loaded into TerraScan run Detect Wires to create both wire vectors and to classify wire points.
Use Fences around Spans
Break the LIDAR data into project blocks and create fences around tower spans. It is recommended that the fences overlap the tower a bit. Run the detect wires routine on the separates spans.
This will create wire vectors, however due to the overlap of the fences, minor cleanup will likely be needed on the vectors. To classify the wire points, a classify by center line routine would need to be run on the project after the vectors have been generated.
Create Project Blocks around Spans
Break the LIDAR data into project blocks based upon a Tower String. Run the detect wires routine on each block to create both wire vectors and to classify wire points. If needing to classify towers, a user would need to go back and do some manual cleanup using this process due to the fact the towers will span across the tile boundaries.
Use a Single Block of Data containing only potential wire points
Create a macro to create one LIDAR file that contains on potential wire points. Load the data into TerraScan and run the detect wires routine on the data as a whole. The output will be the wire vectors, which a user would need to cleanup the start and end points of. Once the vectors have been cleaned up a user would then be able to classify the LIDAR data in the original project using the the classify by center line option.