Generation of Thermal Point Clouds From Uncalibrated Thermal Infrared Image Sequences and Mobile Laser Scans

Monitoring building efficiency is a hot topic for engineers and researchers. Thermal infrared (TIR) images describe thermal attributes but require professional knowledge for analysis. Moreover, images can hardly describe the thermal attributes of the buildings in all aspects. Therefore, as-built thermal point clouds become the solution. In this case, geometric distortions of TIR images cannot be neglected. To generate the thermal point clouds with TIR image sequences, we propose to use mobile laser scanning (MLS) point clouds as control point sets for calibration and a workflow for the thermal point cloud generation. To begin with, intensity images are generated from the point clouds, and corresponding points are detected from the TIR image and intensity image frame. Moreover, the intrinsic parameters are estimated with corresponding points. Finally, the thermal point clouds are generated with calibrated TIR images and MLS point clouds. The result demonstrates that the automatic method can achieve comparable or even better calibration results than the manual method.