ABSTRACT
This paper discusses an application of vision metrology to tunnel profile measurement. In general vision metrology is less reliable unless a strong observation network is available. In tunnel profile measurement, weak camera configurations are often inevitable because of its geometrical constraint. To cope with this difficulty, the authors have extended the basic strategy of vision metrology with a single camera to one reinforced by auxiliary observations with a total station. The augmented observation equations are solved by inner constraints, which are required of some modifications due to reduction of the rank of the null space of observation equations. The usefulness of the method is illustratively shown for a measurement experiment on a tunnel of 10m in diameter. The adjusted object space coordinates of targets are compared those independently observed by a total station for check. The root mean square of differences of the coordinates is reduced from 1.43 mm with the basic observation method to 0.95mm with the improved method.
