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Scientia Silvae Sinicae ›› 2019, Vol. 55 ›› Issue (11): 63-72.doi: 10.11707/j.1001-7488.20191108

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Stem Volume Calculation Based on Stem Section Profile Curve and Three Dimension Laser Point Cloud

You Lei1,2,3, Ha Denglong4, Xie Mingkun1, Zhang Xiaopeng2, Song Xinyu5, Pang Yong6, Tang Shouzheng6   

  1. 1. College of Computer and Information Technology, Xinyang Normal University Xinyang 464000;
    2. National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences Beijing 100190;
    3. Henan Key Laboratory of Analysis and Applications of Education Big Data, Xinyang Normal University Xinyang 464000;
    4. Jigongshan National Nature Reserve, Henan Province Xinyang 464133;
    5. College of Mathematics and Statistics, Xinyang Normal University Xinyang 464000;
    6. Research Institute of Forest Resource and Information Techniques, CAF Beijing 100091
  • Received:2019-03-11 Revised:2019-10-17 Online:2019-11-25 Published:2019-12-21

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Abstract: [Objective] In order to accurately calculate the stem volume, a stem volume calculation method based on the section profile curve, which using the stem point cloud scanned by the terrestrial laser scanner, is proposed in this paper.[Method] The method divided the stem point cloud into several vertical segments with identical length according to the height value thick. For each vertical segment, the method firstly projected the stem points of the vertical segment to the lower section plane to obtain a planar point set, and the convex points of the planar point set were obtained. The centroid of the closed convex hull polygon formed by the convex points was seemed as a center point, and the planar point set was angular partitioned by the angle value θ. The gravity of the points in an angle partition is the contour point of the angle partition. And the angle partition without a contour point was repaired by the adjacency and continuity in the same angle partition between the upper and lower vertical segments. Then the contour points of all angle partitions of the current vertical segment were used as interpolation points, and a cubic B-spline curve with smooth and continuous was interpolated on the interpolation points. The cubic B-spline curve is called as a section profile curve of a vertical segment. The area enclosed by the curve is the stem sectional area. The product of the cross-sectional area and height is the volume of the vertical segment, and the volume of all vertical segments is the volume of the stem. The simulated point cloud of cylinder, cone and parabolic bodies, the volume of which is accurately calculated by the volume formula, and 183 stems with the length of 1 m from 7 tree species were used as experimental materials for simulation and measured experiment.[Result] The simulation experiment showed that the accuracy of our method is better than that of the fitted circle, the fitted cylinder and the Bézier convex curve method for the volume calculation of the cone and parabolic bodies. The measured experiment showed that compared with the volume(thick=2 cm,θ=2°)calculated by the section profile curve method, the MAPE, RMSE and TRE of the stem volume calculated by the fitted circle, the fitted cylinder and the Bézier convex curve method are 0.64%, 433.65 cm3 and 0.54%, 0.63%, 429.06 cm3 and 0.53%, 11.88%, 3 361.36 cm3 and 9.51%, respectively.[Conclusion] Based on the calculation theory analysis and experimental verification of the four methods, it is concluded that the stem sectional area and stem volume calculated by the section profile curve methods are the most accurate, and the stem sectional area and stem volume calculated by the traditional methods are larger than its true value.

Key words: terrestrial laster scanning(TLS), stem volume, section, sectional area, profile curve

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