Trinocular vision and spatial prior based method for ground clearance measurement of transmission lines.

It is an essential task to inspect ground clearance of transmission lines in time. However, the weak texture of transmission lines and high complexity of the background make it difficult to balance efficiency and accuracy. To solve the problem, a trinocular vision and spatial prior based method is proposed, which is specifically designed for ground clearance measurement of transmission lines with unmanned aerial vehicles (UAVs). In this novel method, a perpendicular double-baseline trinocular vision module is applied to improve the accuracy of transmission line reconstruction. Then the spatial prior information of geometric models under different shooting attitudes is analyzed in detail, and it is adopted to determine the ground crossing points and compute ground clearance efficiently. Also, an interactive software is developed and tested in the simulation environment of UAV inspection. Experimental results verify the feasibility of the measurement method. Finally, we discuss in detail how to apply the method effectively in practice and give a set of recommended camera parameters.