LiDAR can be used to obtain forest spatial structure and terrain under canopy with high precision by transmitting laser energy and receiving returned signals. Full waveform LiDAR is able to record whole energy of returned signal and characterize vegetation vertical profile with sub-meter. Discrete return LiDAR records single or multiple echoes from stratified canopies. Spaceborne LiDAR usually configures laser profiling system with full waveform or photo counting technique to acquire single or multiple beams data under satellite orbit for vertical structure or change observation of forest at regional or global scale. Airborne LiDAR often use laser scanning system with discrete return or full waveform technique to obtain scan data within special FOV under flight trajectory for structure measurements of forest at stand or regional scale. Terrestrial LiDAR mainly carry laser scanning system with discrete return technique to get scan data within spherical space centered at observing station for detecting vertical structure of individual trees or forest stand. Inversion methods of individual tree parameters may be group into three category including CHM-based

NPC-based and voxel-based methods. CHM-based methods recognize tree tops by local maximum algorithm

and detects crown edges or crown main direction by region growth or image segmentation. NPC-based methods distinguish individual trees by spatial clustering or morphology algorithm. Voxel-based methods identify tree crown by region growth or spatial clustering algorithm in 3D voxel space. Forest stand parameters can be estimated using individual tree based or canopy height distribution based method. The features of canopy height distribution may be extracted from point cloud or full waveform. Multiple temporal LiDAR can be used to monitor forest growth

biomass change

structure changes caused by deforestation or disaster. It will be widely used in the field of operating organization or scientific research such as forest inventory

ecosystem modelling

etc. as the development of LiDAR technique.