LiDAR system calibration using point cloud coordinates in overlapping strips

LiDAR systems have become a popular technology, which provides fast and accurate acquisition of object space surface models. The process for correcting the LiDAR data, which is distorted by systematic errors, is accomplished either through strip adjustment or LiDAR system calibration. The strip adjustment reduces or eliminates the discrepancies between overlapping strips using the point cloud coordinates. On the other hand, the calibration procedure recovers systematic errors using the LiDAR equation and system raw measurements from the GPS/INS and laser scanner. The advantage of the strip adjustment is that end-users can reduce the discrepancies between overlapping strips, which are caused by systematic errors, without requiring the availability of the system raw measurements. This approach, however, is limited to the overlapping strips that are considered. This paper proposes an alternative calibration method, where the LiDAR point cloud from overlapping strips are utilized and a simplified LiDAR system equation is derived using few reasonable assumptions. A 3D transformation function is applied to the overlapping strips, and the transformation parameters are estimated using the discrepancies between overlapping strips. After this, the estimated parameters are used to determine the correction terms for the initial calibration parameters based on the relationship between the transformation parameters and systematic errors, where the relationship is derived from the simplified LiDAR equation. The correspondence between overlapping strips is also discussed. In this research, areal and linear features are used as alternative primitives. The feasibility of the proposed method and alternative primitives will be investigated through experimental results from real LiDAR data.