How To Use the Rail Extractor

1. Use the Add Files command to open the LAS files that contain the rails that you want to extract.

2. Use the Add Task command to create a new task. When you are selecting a Task Type in the Add Point Cloud Task dialog, select Rail Extractor. On the Point Cloud Task tab again, you should see the unique name that you gave your task selected in the list and the Rail Extractor properties displayed.

Overview of the Rail Extractor Properties Window

1. To specify the input seed line source, click the browse button next to Input Seed Line Geometry. The I/O Manager will display.

2. In the I/O Manager, select one of the following options to use to define the rail seed line:

   1. Tool Geometry - select this option to use one of the drawing tools in the map to define the area from which to extract rails.

   2. SHP Layer - select this option to use a currently loaded linear shape layer.

   3. File - select this option if you have a specific file that defines the lines you want to use to extract rails.

3. On the Point Cloud Task tab, click the browse button next to Input LAS Layer to select the layer to use for the extraction.

4. In the I/O Manager again, click the drop-down arrow under Map Layer and select one of the Layers available in the list. Only the LAS Layers currently open in LP360 are available, so if you want to use a Layer other than one listed, you must first open it using the Create LIDAR Layer command. To use the Active LIDAR Layer, select the [Active LAS Layer] option.

5. Next, click the Source Points button directly under the Input LAS Layer list.

6. In the Input Point Filter dialog that displays, select the classes that you want the points to be filtered by. This filter will be applied in the rail extraction algorithm.

7. Check the Classify LAS Rail Points checkbox to classify the computed rail points.

8. If you checked Classify LAS Rail Points, click the Source Points button under Classification Settings.

9. In the Classification Point Filter dialog, select the classes that the points must pass before being re-classified. 

10. Click the Destination Class button under Classification Settings.

11. In the Destination Class dialog, set the flags to Ignore, Set (to turn on the flag), or Clear, then click OK.

12. Select Create Centerline Shapes to create a vector SHP file for the rail centerline.

13. Click the browse button next to the Create Centerline Shapes field. The I/O Manager dialog will display again.

14. In the I/O Manager dialog, select the location where you want the file to be created.

15. Under Output Mode, select Append if you would like the centerline to be combined with the existing file (if it exists) or Overwrite to replace its contents with the new centerline vector. 

16. If you want the SHP file opened and the centerline displayed in the current map display, click Add to Map.

17. On the Point Cloud Task tab, enter a value in map units in the Vertex Spacing field.

18. Click the Extend until Lost to have processing continue beyond the specified seed line. 

19. Click the Re-center on Extraction End to re-center the view on the end point of the rail extraction if you are using Tool Geometry to define the seed lines.

20. Select an existing Rail Extraction parameter set from the Parameter Set list.

21. If you selected Tool Geometry as the method to define the input seed line, select the Linestring tool on the PCT toolbar.

22. Draw the line in the map to define the rail that you want to use for the rail extraction.

23. Click Apply.

24. Observe your results in the map and by using the Information button.