## Extract Point Cloud Boundary

### Summary

Use a regular hexagon to extract the boundary of a point cloud data. According to the Extraction Hexagon Height, determine the height of each regular hexagon, and draw each hexagon based on the bounding box of the point cloud data. If the number of points within a hexagon is greater than or equal to the user-defined Minimum Number of Points value, this hexagon will be kept and merged with its connected hexagons. The ultimate output file is the final border vector file. ### Usage

Click Data Management > Point Cloud Tools > Extract Point Cloud Boundary ### Settings

• Input Data: The input file can be a single point cloud data file or multiple data files. File Format: *.LiData.

• Extraction Methods: Choose the method to extract the boundary. Currently supports three methods, hexagon, convex hull, and concave hull.

• Hexagon (Default): Use hexagon to extract the boundary of the the data. Set the Hexagon Height to determine the size of the hexagon. And draw every hexagon according to the minimum bounding box of the data. If the points inside the hexagon is more than Minimum Number of Points, then draw the hexagon. Merge the adjacent hexagons to generate the shapefile of the boundary.
• Hexagon Height (m)(default value is "10"): The height of the hexagon, which is used to set the size of drowning a hexagon.
• Minimum Number of Points (default value is "1"): The thresholding number of points in a hexagon, below which no hexagon will be drawn.
• Convex Hull: Extract the 2.5-demantional convex hull of the point cloud in the XY plane (ignore the Z value). The output file is the vector file (polygon) of the convex hull of the original point cloud. Each node of the polygon is extracted from the points in the point cloud (with Z value).
• Concave Hull: Extract the 2.5-demantional concave hull of the point cloud in the XY plane (ignore the Z value). The output file is the vector file (polygon) of the concave hull of the original point cloud. Each node of the polygon is extracted from the points in the point cloud (with Z value).

• Maximum Side Length (m)(default value is "2"): The max. side length of all the sides of the output concave hull. The software first detects the convex hull of the point cloud, then loops inward to capture the concave hull, and ensures that the maximum side length is not greater than this value. When the value is too large, the calculation efficiency is improved, but the result will not show the boundary details of the point cloud well; if the value is too small, the boundary will be clearly show the details, but the calculation efficiency will be reduced. Therefore, in order to obtain the best extraction results, it is recommended that users set this value to be more than 2 times the average distance of the point cloud. The users can also set this value to zero. At this time, the program will automatically estimate the average distance between all the points, and set the parameter as twice of the average distance.
• Output path: Path of the output file. A new boundary vector file will be generated after the algorithm is executed. File format: *.shp.