Abstract
LiDAR (Light Detection and Ranging) can provide accurate remote sensing data for extracting surface information, and
large footprint LiDAR has demonstrated great potential for accurately measuring forest canopy characteristics, which are
important for regional and global climate change studies. In this study the Geometric Optical Model, Radiative Transfer
Model and hotspot condition are used to explore the relationship between canopy structure and large footprint LiDAR
return waveforms. A simplified model was simulated, and detailed analysis was made. The model was improved by
adding an extinction coefficient and a scatter coefficient, and then some simplified parameters are introduced to the
model. The new 3D model is simulated by considering the characteristics of large footprint LiDAR and forest stand. The
experiment results show that terrain slop can influence LiDAR return waveform shapes greatly, while tree height just
affects the starting position of waveforms, and the effects of terrain slop and extinction is reduced obviously. The new
model was validated with field data of Changbai Mountain, and the results have good agreement with GLAS data, and
relatively, the improved model and simulation of waveform fit the actual return waveform of large footprint LiDAR
system.
