中文摘要：

小光斑激光雷达已被广泛用来估测森林参数,为了进一步提高其估测单木的精度,选取了内蒙古依根试验区野外测量的单木数据和机载LiDAR数据,提出了四次多项式拟合法。该方法首先以单木顶点为中心在CHM上提取东西、南北2个方向的高程数据。然后分别得到2组数据的四次多项式拟合曲线,曲线中两凹点之间的水平距离为该方向的冠幅值。最终将2个方向的均值作为单木冠幅估测值,冠幅估测值的平均绝对误差为0.99m。

英文摘要：

Currently, the small-footprint LiDAR has been widely used to estimate forest parameters. In order to further improve the estimate accuracy of individual tree, field measured individual tree data and airborne LiDAR data in Eagan area of Inner Mongolia were selected, and a fourth degree polynomial fitting method was put forward. In the method, firstly, the top of individual tree was centered, elevation data on Canopy Height Model （CHM） at the north-south and the east-west directions were extracted. Secondly, two fourth degree polynomial fitting curves were extracted on the two group data, respectively. The horizontal distance between two pits on the curve was considered as crown diameter at this direction. Finally the crown diameter was calculated as the average of two values measured along two directions. The analysis showed that mean absolute error of individual crown diameter was 0.99 m.