ABSTRACT
Large structures such as pylons and bridges have to be inspected periodically. When deteriorated structural steels are found, they are replaced with new ones. Since bolt positions and dimensions of new structural steels have to be precisely manufactured, it is necessary to measure deteriorated steels. In the conventional method, inspectors have to climb a large structure to measure structural steels. The terrestrial laser scanner can capture dense point clouds of structural steels at a distance position. In this study, we describe methods for automatically extracting structural steels and bolts from point clouds of pylons to determine their dimensions and positions. Then we investigate the feasibility of our method using actual point clouds of power transmission pylons. In our evaluation, we showed that structural steels and bolts could be stably detected and the bolt positions could be precisely calculated.
