Automatic calculation method of tree diameter at breast height based on voxel growth and ground laser point cloud

Abstract

The invention discloses an automatic calculation method of the tree breast diameter based on voxel growth and ground laser point cloud. The method is based on three-dimensional point cloud data obtained by ground laser scanning. Firstly, the point cloud above the ground is intercepted and below 3 meters, leaving only the trunk part required for breast diameter measurement, and then the ground point is filtered out. Then, the Z component of the point cloud normal vector is used to filter and voxelize the remaining point cloud, and the trunk is extracted by the top-down growth method. Then, thetrunk is sliced, and the plane perpendicular to the trunk is obtained by the cross multiplication of the trunk point cloud normal vectors. Finally, the point cloud slices are projected onto the planeand the DBH of the tree is obtained by circle fitting. The method has the advantages of fast calculation speed, high accuracy and universality, can be applied to complex and dense forest area environment, and can play a better role in forest resource planning and investigation.

Description

technical field [0001] The invention relates to a method for calculating the diameter at breast height of a tree, in particular to an automatic calculation method for the diameter at breast height of a tree based on voxel growth and ground laser point clouds. Background technique [0002] Terrestrial laser scanning technology is widely used in the measurement of tree diameters in forest resource surveys. One of the most difficult points in this work is how to quickly and accurately extract tree trunks from a large amount of point cloud data collected by ground laser scanning. and overcome noise. [0003] At present, there are mainly four methods for measuring the DBH of trees using the point cloud data obtained by ground laser scanning: [0004] The first method is to directly measure the distance between two points to calculate the diameter of the tree, which is measured by visually selecting points, usually because the selected two points are not the two points that make ...

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Problems solved by technology

[0006] The third method is to use the Hough transform to detect the trunk and measure its DBH. Due to the large number of point clouds, the Hough transform requires a lot of calculations and takes a long time;

[0007] The fourth method is to perform cylindrical fitting on the trunk point cloud to obtain the tree diameter at breast height, but the calculation process is too cumbersome no matter whether the Gaussian graph method, genetic algorithm or feature algorithm is used for cylindrical fitting, and this method is not suitable for trees with a certain inclination. Trunk fitting accuracy is not enough

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