An automatic calculation method of tree diameter at breast height based on ground lidar scanning

Abstract

The invention discloses a ground laser radar scanning-based automatic tree breast-height diameter calculation method. According to the method, the calculation speed and robustness of the algorithm are improved through trunk cutting and filtration; the condition that the breast-height diameters of the trees cannot be calculated as point clouds do not exist at the 1.3m places or the noise is too loud through automatic selecting point clouds to carry out fitting; the problem of incorrect circle fitting caused by the trunk growth angle problem is overcome through cylinder fitting; and the calculation precision is improved through a sliding window fitting cylinder. The method has nothing to do with the density, is insensitive to partial deficiency of the trunks and overcomes the problem that the long-distance trees are difficult to extract as the density is too low or loss is caused due to sheltering; and the method is independent of scanning station number, has no requirements for the fact whether the trunk point clouds are circular or not, and can achieve good effect even single-station scanning is carried out.

Description

technical field [0001] The invention relates to remote sensing measurement technology, in particular to an automatic calculation method for tree diameter at breast height based on ground laser radar scanning. Background technique [0002] DBH measurement means measuring the diameter of the trunk at 1.3 meters. At present, it is mainly obtained manually, mainly using a tree-measurement DBH ruler. Even if a small number of forestry departments use airborne lidar scanning for measurement, they cannot obtain good measurement accuracy due to defects in scanning angles and low levels of automatic fitting and interpretation, so that remote sensing can only obtain some qualitative information. Forest parameters cannot be obtained quantitatively. [0003] First of all, for the airborne scanning method, due to the problem of the scanning angle, most of the data obtained from the point cloud is tree crown data. Due to the occlusion of the tree crown, the trunk point cloud is prone to ...

AI Technical Summary

Problems solved by technology

The method of height fitting DBH can only give the average DBH of the tree species through the height, but cannot give the DBH of a specific tree, and cannot give accurate measurements for the growth of a single tree and the calculation of the volume of a single tree;

[0006] 2. Directly measure the distance between two points to calculate the DBH. This method uses the method of visually selecting points for measurement. Usually, the calculation is inaccurate because the selected two points are not the two points that make up the diameter or the shape of the trunk changes;

[0007] 3. Using a circle to fit the diameter at breast height is the most commonly used method in measuring the diameter at breast height by using laser radar. At 1.3 meters, a section of point cloud is intercepted at a certain height (such as 10 cm), and then vertically projected onto the plane, and then the circle is used to simulate DBH, this method often affects the projection effect due to the inclination angle of the tree trunk, causing the fitted circle to deviate from the actual value. When the noise is relatively large, this method will also cause inaccurate calculation results due to the influence of noise

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