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Scientia Silvae Sinicae ›› 2018, Vol. 54 ›› Issue (7): 62-72.doi: 10.11707/j.1001-7488.20180707

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Individual Tree Structure Parameters and Effective Crown of the Stand Extraction Base on Airborn LiDAR Data

Geng Lin, Li Mingze, Fan Wenyi, Wang Bin   

  1. School of Forestry, Northeast Forestry University Harbin 150040
  • Received:2017-08-16 Revised:2018-03-21 Online:2018-07-25 Published:2018-08-11

Abstract: [Objective] This study was performed in coniferous plantations in Mao'ershan Experiment Forest centre of Northeast Forestry University. The three-dimensional structural parameters of individual tree canopy, which included treetops position, tree height, crown size and crown height, in the study area were extracted using airborne LiDAR data. And on this basis, the effective canopy was extracted to obtain the effective canopy of the stand.[Method] In this study, we used the local maximum window with variable window sizes to search the treetops of the crown, and to identify the treetops of individual tree crown and the extraction of individual tree. Using the crown treetops mark, marker-controlled watershed method was applied to segmentation algorithm into isolating individual trees. The vertical point cloud elevation detection method was analyzed to obtain the crown base height position, then the crown height was extracted. At the border of the canopy which was divided into marker-controlled watersheds, extraction of two crowns was contact height, averaging was taken as the effective crown of the stand.[Result] The results showed that the accuracy of tree isolation was 88.5%. The correlation analysis of the extracted values was carried out by using the measured data. The R2 of tree height, crown diameter size and crown height was 0.886 2, 0.786 4 and 0.800 0, and the corresponding precision was 90.34%, 86.80%, 89.90%, respectively. The average contact height in the same forest stand was relatively stable. One-factor analysis of variance(ANOVA)was performed on the effective crown height of the extracted stands. No significant difference was found when the P-value was greater than 0.05.[Conclusion] A local maximum algorithm can be used by LiDAR to extract tree crown vertex and tree height. The variable size dynamic window is used to search for local maximum points. This method can improve the extraction accuracy of tree canopy structure parameters. Based on the tree top mark control watershed algorithm, the LiDAR data can be combined with the high spatial resolution navigation chip to complete the high-precision canopy extraction. The vertical direction detection method can extract the single crown length efficiently. In the same forest, the effective canopy of the stand is roughly the same. The airborne LiDAR can be able to extract the three-dimensional structure parameters of the single tree canopy, and can satisfy the extraction of the parameters of the single tree by the modern forestry survey and the extraction of the effective canopy of the stand.

Key words: LiDAR, crown diameter size, trees height, crown height, effective canopy of the stand

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