Since the reform and opening up, China's forestry industry has experienced rough development and utilization while China's economy were advancing by leaps and bounds. Forests have been drastically reduced, and the ecological environment has deteriorated. However, with the proposal of China's sustainable development strategy in recent years, the construction of ecological civilization is becoming more and more important. The forestry census is also an important part of the construction of ecological civilization.
Forest Census is to use either conventional measurement or photogrammetry to measure the forest trees, obtain the type, distribution, growth status, coverage area, wood storage volume and pests and diseases of the trees, in the purpose for providing decision support for the optimal management of forestry resources.
In forest mapping, airborne LiDAR is similar to traditional photogrammetry, but better than photogrammetry. With its penetrating and multiple echo characteristics, it can obtain more forest information than photogrammetry. Therefore, 3D laser scanning measurement technology has unique advantage in forestry survey.
Forestry mapping is the major methodology of forestry census. It is mainly divided into two processes: data acquisition and data processing. Data acquisition is to use the on-board LiDAR to scan the forest and obtain the point cloud and image of the forest vegetation. Then the data is processed to produce the DTM of the forest area for the further analysis of the crown width, growth density, area, wood stock and growth trend of the trees.