Abstract
A procedure for both vertical canopy structure analysis and 3D single tree modelling based on Lidar point cloud is presented in this paper. The whole area of research 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 modelling of individual trees, individual trees are detected and delineated not only from the top canopy layer but also from the sub canopy layer. The normalized points are resampled into a local voxel space. A series of horizontal 2D projection images at the 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 the different height levels. Finally, 3D tree crown models of the extracted individual trees are reconstructed. With further analyses on the 3D models of individual tree crowns, important parameters such as crown height range, crown volume and crown contours at the different height levels can be derived.
Highlights
The vertical canopy structures of stands are of high interest in forest management
The Digital Terrain Model (DTM) is generated from the raw point clouds based on the active contour algorithm implemented by TreesVis, a software for LIDAR data processing developed by Department of Remote
For the 3D single tree modelling, the advantage of our algorithm is that the individual trees whose crowns are at the top canopy layer, and the lower trees and even trees at sub canopy layers whose crowns are covered by the top canopy layer are extracted
Summary
The vertical canopy structures of stands are of high interest in forest management. The knowledge of the vertical canopy structure improves regression models for estimation of wood volume and biomass and the information of sub canopy layer will benefit the management of new growth in forest. Lidar is especially suitable to reproduce the vertical canopy structure of forest stands due to its capability of three-dimensional measurements with high accuracy. The utilization of Lidar in forest investigation can be generally divided into canopy height distribution based and single tree detection based. Trees are delineated according to the features of crowns on the DSM, the individual trees in the lower canopy layer whose crowns are covered by the top canopy layer cannot be detected. We will present a procedure for both vertical canopy structure analysis and single tree modelling in forest based on Lidar raw point clouds. The Lidar data is a first-last echo data with point density of 4~7 points/m2, which is delivered by Toposys
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
