Large Footprint Lidar Waveform Modelling of Forest Spatial Patterns
林木空间格局对大光斑激光雷达波形的影响模拟

Large footprint lidar has demonstrated its great potential for accurate estimation of many forest parameters,e.g.forest height,forest biomass and vertical structure of forest canopy.In addition to the canopy vegetation, many factors such as atmosphere,underlying surface,the shape of crown,et al.,influence the lidar waveform.The illuminating intensity of the laser beam across the lidar footprint is a Guassian distribution and reduces from 1.0 to e~(-2) from the center to the edge of the footprint.So the forest stand spatial pattern plays an important role in the lidar waveform.The contribution of each tree to the lidar waveform varies with its location in a forest stand.This paper simulated the random,uniform and clumped tree distribution patterns in a stand.Then waveforms were simulated using a three dimensional lidar waveform model.The results show that the tree distribution patterns affect the lidar waveform profiles.The area(or energy) under the waveform from vegetation(AWAV) and the height of median energy(HOME) were used to estimate the effects.Following trends have been revealed from the simulation: for AWAV and HOME,uniform>random>cluster.The difference between uniform and random is not obvious.For the clumped case,the number of clusters does not have much effect on the lidar waveform.