Modeling lidar returns from forest canopies

• Published in: IEEE transactions on geoscience and remote sensing 2000-11, Vol.38 (6), p.2617-2626
• Main Authors: Sun, G., Ranson, K.J.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied geophysics; Atmospheric modeling; Biological and medical sciences; Canopies; Computer simulation; Earth sciences; Earth, ocean, space; Exact sciences and technology; Forests; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Geometry; Growth models; Internal geophysics; Laser radar; Lidar; Ray tracing; Remote sensing; Shape measurement; Stands; Sun; Supports; Surface emitting lasers; Surface topography; Teledetection and vegetation maps; Vegetation; Vegetation mapping; Waveforms
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/36.885208

Remote sensing techniques that utilize light detection and ranging (lidar) provide unique data on canopy geometry and subcanopy topography. This type of information will lead to improved understanding of important structures and processes of Earth's vegetation cover. To understand the relation between canopy structure and the lidar return waveform, a three-dimensional (3D) model was developed and implemented. Detailed field measurements and forest growth model simulations of forest stands were used to parameterize this vegetation lidar waveform model. In the model, the crown shape of trees determines the vertical distribution of plant material and the corresponding lidar waveforms. Preliminary comparisons of averaged waveforms from an airborne lidar and model simulations shows that the shape of the measured waveform was more similar to simulations using an ellipsoid or hemi-ellipsoid shape. The observed slower decay of the airborne lidar waveforms than the simulated waveforms may indicate the existence of the understories and may also suggest that higher order scattering from the upper canopy may contribute to the lidar signals. The lidar waveforms from stands simulated from a forest growth model show the dependence of the waveform on stand structure.