The laser rangefinder is an active remote sensing technology that measures the distance between the sensor and the target through the laser light emitted by the sensor (lidar). According to the different detection targets, the technology can be divided into two types: aerial detection and ground detection. Laser ranging from the air is designed to measure the physical and chemical properties of the atmosphere by emitting laser beams into the air and receiving echoes reflected by suspended particles in the air. The main purpose of laser distance measurement is to obtain surface information such as geology, topography, landform and land use status. According to the classification of the sensor loading platform, laser ranging can be divided into four categories: satellite loading (satellite loading), aircraft loading (aircraft loading), vehicle (vehicle) and positioning (fixed-point measurement).
Laser ranging technology started in the 1960s and has been an important part of electronic ranging equipment since the 1970s and 1980s. Lidar (Light Detection And Ranging) usually refers to airborne laser-to-ground ranging technology. Lidar is usually used instead of Lidar in Chinese terms. Since the 1970s, many agencies in the United States, including Air China, the National Aeronautics and Space Administration of the United States, the National Oceanic and Atmospheric Administration of the United States, and the Meteorological Administration of the United States, began to develop lasers for ocean and topographic surveys. Radar sensor. In Europe, laser ranging research started almost at the same time as the United States. Unlike the United States, they are committed to the development of satellite platform laser ranging radar systems, paying more attention to the development and research of airborne platforms and their supporting lidar systems, and have achieved considerable Success.
In the 1990s, with the development of airborne global positioning system technology and portable computer systems, the stability and accuracy of lidar systems have been greatly improved, and they have gradually begun to be put into commercial use in Europe. Europe unfolds.
Compared with other remote sensing technologies, the research on lidar is a very new field. The research on improving the accuracy and quality of lidar data and enriching the application technology of lidar data is quite active. Different from remote sensing image technology, the lidar system can quickly obtain the three-dimensional geographic coordinate information of the ground surface and corresponding ground objects (trees, buildings, ground surface, etc.). ), its 3D characteristics meet the mainstream research needs of today's digital earth.
With the continuous improvement of lidar sensors, the gradual increase in the density of ground sampling points, and the increase in the number of recoverable waves of a single laser, lidar data will provide more abundant information on the surface and ground features. By filtering, interpolating, classifying and segmenting the three-dimensional surface point set collected by lidar, various high-precision three-dimensional digital surface models can be obtained, and the surface features can be classified and recognized to achieve three-dimensional surface features such as trees and buildings. Digital reconstruction can even draw three-dimensional forest and city models to build virtual reality. A more detailed analysis of ground features based on virtual reality can estimate the parameters of forest land and its individual plants, so as to realize fine forest farmer management; it can simulate and analyze urban planning, urban environment, and urban climate, and realize sound, light, and environmental pollution assessment and control.
