Method for calculating extinction coefficients of three-dimensional forest canopy by using laser-point cloud

A technology of laser point cloud and extinction coefficient, applied in the field of calculating forest canopy extinction coefficient, can solve the problem of insufficient depth of canopy extinction coefficient

Inactive Publication Date: 2013-02-06
NANJING UNIV
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Problems solved by technology

However, the current domestic research theory and technology for extracting canopy extinction coefficients from 3D point cloud data obtained by lidar is not deep enough, and needs to be further strengthened.

Method used

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  • Method for calculating extinction coefficients of three-dimensional forest canopy by using laser-point cloud
  • Method for calculating extinction coefficients of three-dimensional forest canopy by using laser-point cloud
  • Method for calculating extinction coefficients of three-dimensional forest canopy by using laser-point cloud

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Embodiment Construction

[0064] The present invention is further explained by examples below:

[0065] Take a Douglas-fir (Douglas-fir) as the research object (the height of the tree is about 25m), use the ground 3D laser scanner Leica ScanStation 2 (the parameters are shown in Table 1) and high-precision GPS, on one side of the tree For the collection of 3D point cloud data, the sampling interval is 2cm. Manually remove the ground point cloud and other noise point clouds to obtain the three-dimensional point cloud data of a single Douglas fir tree, as attached Figure 4 Shown.

[0066] Table 1 Three-dimensional laser scanner Leica ScanStation 2 parameters

[0067]

[0068] After obtaining Douglas fir point cloud data and preprocessing, as attached figure 1 As shown, computational geometry technology is used to process 3D point cloud data. The first step is 3D meshing, the second step is voxel-based point cloud slicing, and the third step is line sampling analysis.

[0069] According to the step (2) of the t...

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Abstract

The invention provides a method for calculating the extinction coefficients of a three-dimensional forest canopy under any given incident ray by using a geometric algorithm, belonging to the research field of a method of acquiring the structural parameters of the forest canopy. The method for calculating the extinction coefficients of the three-dimensional forest canopy by using the geometric algorithm comprises the following steps: acquiring and preprocessing the three-dimensional laser-point cloud data of a plant canopy; carrying out three-dimensional gridding on the point cloud data; carrying out point cloud slice arithmetic based on a voxel data structure; carrying out linear sampling analysis on the point cloud slices; calculating an average projection coefficient of a kth layer of slices; and calculating the extinction coefficient of any given incident ray in each layer of slices and the extinction coefficient of whole canopy. Compared with the traditional observing way, the invention has the characteristics of being small in working amount, and free from the contact observation and the damage of the canopy structure and radiation, and has objectiveness, high efficiency and precision; a method of extracting the three-dimensional structures and biological and physical diversity information from the laser radar data is developed to characterize the horizontal and vertical distribution change rules of the leaves.

Description

1. Technical Field [0001] The invention relates to a method for calculating the extinction coefficient of the forest canopy by using point cloud data obtained by a ground three-dimensional laser scanner, specifically, it refers to an improved calculation of the three-dimensional forest canopy with any given incident light using a computational geometric algorithm The method of extinction coefficient under the figure 1 Shown). 2. Background technology [0002] The forest canopy structure occupies an important position in the interaction of soil-canopy-atmosphere and is closely related to the material and energy exchange in the biogeochemical cycle. The extinction coefficient is defined as the average projected area per unit leaf area on a plane perpendicular to the direction of light. It is an important factor for quantitatively understanding forest canopy structure and radiation transmission. It is calculated based on the directional distribution function of the leaf inclination...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/17
Inventor 郑光张乾冯永康
Owner NANJING UNIV
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