Over the past few years, LiDAR or laser scanning systems (airborne, static and terrestrial mobile mapping systems) are considered as well-accepted technologies that can quickly acquire precise 3D point clouds of the terrain surfaces. On the functional level, any mobile system could be defined as an integration of several subsystems such as: Global Positioning System (GPS), an Inertial Navigation System (INS), and the laser scanner. To ensure the geometric quality of the collected point cloud, LiDAR systems should undergo a rigorous calibration procedure. LiDAR system calibration comprises individual sensor calibration (i.e., laser ranging and scanning unit) and mounting parameters calibration (i.e., lever arm offset and boresight angles) relating the system components such as the GPS, INS, and laser scanner. In this research work, a new method for automatic selection of suitable overlapping strip pairs/regions for optimized LiDAR system calibration is introduced. The experimental results have shown that the quality of the estimated parameters using the automatic selection is quite similar to the estimated parameters using the manual selection while the processing time of automatic selection is 3 times faster than the manual selection.
In the field of surveying and mapping in recent years, the development of airborne LiDAR systems is characterized by the use of multiple laser scanners for accurate and efficient capture of 3D data along ground and above ground features. In this research, new calibration procedure for dealing with airborne multi-laser scanning systems is presented. The experimental results have shown that accurate estimation of the calibration parameters of each laser scanner can be obtained using the proposed method.
Terrestrial mobile laser scanning (TMLS) is the latest approach towards fast and cost-effective acquisition of 3-dimensional spatial data. Accurately evaluating the intrinsic and mounting parameters of TMLS systems is an obvious necessity. However, available systems on the market may lack suitable and efficient practical workflows on how to perform this calibration. This research introduces an innovative method for accurately determining the intrinsic and mounting parameters of multi-TMLS systems. The proposed calibration method investigates a two-step (indoor followed by outdoor) calibration procedure for calibrating terrestrial mobile multi-laser scanning systems. In this research work, a simulation program is developed for generating 3D LiDAR data such as a Velodyne-based Mobile laser scanning system (HDL-32E). The experimental results are performed using a simulated dataset for investigating the one-step and two-step calibration procedures. The experimental results have shown that the estimated parameters using the two-step calibration procedure are better than the estimated parameters derived from the one-step calibration procedure.