Entwicklung eines Videotheodolit-Meßsystems zur automatischen Richtungsmessung von nicht signalisierten Objektpunkten

Abstract

The combination of CCD cameras and motorized theodolites enables the development of powerful measuring tools, so called measurement robots. Such an automatic measuring system based on two videotheodolites is described. It is possible to measure active or passive targets and non signalized points. Due to the stepper motors of the axes of the theodolites and the focal lens the field of view is nearly unlimited and moving targets can be pursued. The orientation of the CCD camera is computed during every measurement nearly in real-time. Different menus help the operator to handle the system. The measurements can be done automatically, but operator interactions help to control the system and to reduce processing time by setting individual thresholds. The target co- ordinates are computed by spatial intersection. Various algorithms guarantee, that the angles to identical points are measured with very high accuracy from every point of view. Non signalized points are found with the 'Foerstner-Operator'. The target area coincidence of all theodolites is reached by combining the epipolar line geometry and a distance information computed with an autofocus function. The accuracy reached in a test measurement under quite bad conditions was 1 : 30.000, so that an maximum accuracy of 1 : 100.000 under optimum conditions seams to be realistic.