Find Poles using TerraScan

The “Find Poles” tool was introduced to the Railroad Tool Box with the release of TerraScan v017.018. While originally intended to automatically detect pole type objects along roads and railroads, which were collected using mobile or high-density airborne LIDAR data, this tool is designed in a manner where it can be used to detect a variety of objects that can be defined. The limitation will be the resolution of the object which is dependent upon the density of the collected data. In other words, this tool can be considered an object detection tool rather than exclusively a pole detection tool.

Find poles can be used to identify the objects, classify the points to that object class, and place cells representing those objects. It does this by comparing groups of points with object templates and assessing the wellness-of-fit. If the fit is good, then the classification and vector placement will occur.

Point Cloud Preparation

Before this tool can be used, there are a few preparatory steps that must be accomplished. Some are similar to those steps one would take for any classification or feature extraction process, such as the LIDAR data needs to be calibrated, overlap cut, and ground points classified. Additionally, the above ground points need to have group numbers assigned for those points in which you’d like to detect the objects. The grouping process requires other routines, such as Compute Distance and Classify by Distance be executed on the source points so that it can group points together based on spatial relationships and assign a group number as a point attribute. Once grouped, the classification of points can be performed on a group basis instead of on an individual point basis.  The goal here is to have a solitary group per object for best results from the Find Poles routine, which can be difficult in some situations as vegetation encroaches on the objects of interest. It might become necessary to manually correct the assigned groups using the Create Point Group or Merge Point Groups tools.

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