The LP360 Rail Extraction tools for LIDAR data automatically extract a rail alignment (centerline) vector as well as classify “top of rail”. This feature is implemented as a semi-automated Point Cloud Task (PCT) and is available in the Advanced version of both LP360 for ArcGIS® and LP360 for Windows® (the standalone version of LP360). We recommend using the ArcGIS version since we do not yet have vector editing tools in LP360 for Windows. We depict in Figure 1 a typical extraction of the alignment and top of rail. The alignment is collected as a set of 3 dimensional vectors in Shape file format. The top of rail points have their Classification Attribute set to the user’s choice of class number being used for rail (10 is the industry standard).
Rail alignment/point extraction requires relatively high density LIDAR data. We have had some success at 40 points per meter2 but recommend around 80 points/m2. The examples we illustrate in thisoverview were collected via helicopter at about 100 points/m2.