What Is Lidar Point Cloud Data?

Apr 28, 2023

Lidar (laser detection and ranging) mainly uses lasers as the emission light source, and is an active remote sensing device that uses photoelectric detection technology. It is an optical remote sensing technology. Primarily used in airborne laser mapping applications, it is increasingly becoming a new cost-effective alternative to traditional measurement techniques such as photogrammetry.

LiDAR is composed of transmitting system, receiving system, information processing and other parts. It uses lasers to densely sample the Earth's surface to produce highly accurate x,y,z measurements. It can generate discrete multi-point cloud datasets that can be managed, displayed, analyzed and shared through ArcGIS.

After the lidar data acquisition measurement is completed, the point data will be post-processed into highly accurate georeferenced x,y,z coordinates by analyzing the time range of the laser, the scanning angle of the laser, GPS position and INS information.

Laser pulses emitted from a LiDAR system reflect off the earth's surface and objects on it: vegetation, buildings, bridges, and more. An emitted laser pulse may return to the lidar sensor in the form of one or more echoes. Any emitted laser pulse that travels toward the ground and encounters multiple reflective surfaces is split into as many echoes as there are reflective surfaces.

After post-processing, spatially organized lidar data is called point cloud data. The initial point cloud is a large collection of 3D elevation points, which include x-values, y-values, z-values, and other attributes such as GPS timestamps. After the initial lidar point cloud is post-processed, specific surface features encountered by the laser can be classified. The ground, buildings, forest canopy, highways, and any objects encountered by the laser beam during measurement constitute the laser point cloud data.