3D Measurement from the Inside of Large Structure Using Ring Laser and a Camera

Abstract

This paper presents an effective 3D measurement method from the inside of large structures such as railway vehicles, elevators, and escalators. In our proposed method, images are captured by a moving measurement device, which is composed of a ring laser and a camera, from the inside of the target object. Structures of the target are reconstructed from these images by integrating cross-section shapes, obtained by the light-section method, into unified coordinate by pose changes estimated by Structure from Motion (SfM). We focus on the method to extract information necessary for the light-section method and SfM from the captured images which contain both laser light and texture information. A color filter used in the proposed method enables to extract areas irradiated by the laser for the light-section method. Further, a new block matching technique is introduced to avoid the influence of the laser light, which causes to detect wrong corresponding points. In experiments, we confirmed the validity of the proposed 3D measurement method.