Development of a Procedure for Vertical Structure Analysis and 3d-single Tree Extraction within Forests Based on Lidar Point Cloud

A procedure for both vertical canopy structure analysis and 3D single tree extraction based on Lidar raw point cloud is presented in this paper. The whole study area is segmented into small study cells by a raster net. For each cell, a normalized point cloud whose point heights represent the absolute heights of the ground objects is generated from the original Lidar raw point cloud. The main tree canopy layers and the height ranges of the layers are detected according to a statistical analysis of the height distribution probability of the normalized raw points. For the 3D extraction of individual trees, the normalized raw points are resampled into a local voxel space. A series of horizontal 2D projection images at different height levels are then generated respect to the voxel space. Tree crown regions are detected from the projection images. Individual trees are then extracted by means of a pre-order forest traversal process through all the tree crown regions at different height levels. Finally, 3D tree crown models of the extracted individual trees are reconstructed.