Intelligent height measurement technology for ground encroachments in large‐scale power transmission corridor based on advanced binocular stereovision algorithms
Zhong Tang, Chenglong Jia, Heng Wang, Shuaiang Rong, Wenbin Zhao
Abstract
Abstract To locate the ground encroachments in transmission line corridor effectively, the application of a novel binocular stereo vision (BSV) for distance measurement is realized with improvement and adjustment in calibration and reconstruction process of BSV. Firstly, a calibration method using a 1‐D pole with spatial constraints to replace the 2‐D calibration object is proposed. The field experiment shows that this method improves the accuracy of the calibration in a large‐scale scene by expanding the calibration area. Then, a regulation algorithm to eliminate the difference between focal lengths for binocular cameras is designed to further improve accuracy of calibration. For practical utilization of BSV in the monitor system, the 3‐D reconstructions from world coordinate system (WCS) to ground‐based system is achieved by rotation and transformation of the reconstructed coordinate system and direct height measurement is realized consequently. Further, based on the calibration method being proposed, the partial calibration with a reduced calibration distribution area is studied considering the probable complex terrain. Height measurement calculations are carried out on both hypothetical and real obstacles to verify the validity of the calibration method and postprocessing algorithms. The results demonstrated that the calibration method algorithms successfully realized the practical application of BSV in large‐scale scene with high accuracy. By using this novel BSV technology, the total transmission line inspection cost is expected to be greatly reduced by comparing with manned helicopter and UAV inspections.