Forest Parameter Inversion And Program Design Based On Airborne Lidar Data

Forest structure parameters such as tree height,crown diameter,leaf area index and leaf area density are important indicators of forest growth and ecological function evaluation.These parameters provide reliable support and basis in forest resource management and climate change policy making.The airborne lidar system not only can acquire the information of the Earth's surface geometry and the echo information of the ground objects accurately and quickly,but also has a strong ability to penetrate the forest vegetation,and it provides a new technical means for the extraction of forest structure parameters and the inversion of forest ecosystem function parameters.Based on airborne lidar data,the main research contents and results are as follows:(1)Research on single tree segmentation algorithm based on airborne lidar data.In this paper,we develop a new algorithm for single tree segmentation which is based on the difference of the cluster relationship between the laser point cloud in a single tree canopy and the adjacent tree point cloud.Field measurement data are used to verify the results of the single tree segmentation,the absolute coefficients of the results are more than 0.7.(2)The algorithm of forest structure parameters is analyzed and a single tree height inversion algorithm is improved.In this paper,we improve parabolic fitting method to estimate the height of single tree based on the single tree point cloud data,which is separated by the single tree segmentation algorithm.The results show that the absolute coefficient is increased by 0.076 and the root mean square error is reduced by about 0.43 meter by using this method;the leaf area index was estimated according to the laser penetration index;the Gauss function is used to reflect the change of LAD with tree height.(3)The ALiDAR_ForForest system is constructed.According to the actual needs of airborne lidar data in forest applications and corresponding design principles,we design and develop ALiDAR_ForForest system for airborne lidar data management,3D display,digital model building and inversion of forest structure parameters.(4)Testing and applying ALi DAR_For Forest system in Shangkuli farm,Inner Mongolia.In this system,the data format of point cloud(las1.0,las1.1,las1.3)is realized;DirectX technology is used to achieve the point cloud data scaling,translation,rotation,view switching,etc;DEM,DSM,CHM are created by using spatial interpolation algorithm;a new algorithm is proposed to separate the canopy and shrub;in order to observe the distribution of single tree canopy,the leaf distribution of single tree is simulated in three-dimensional space,etc.