A CIRCLELESS "2D/3D TOTAL STATION": A LOW COST INSTRUMENT FOR SURVEYING, RECORDING POINT CLOUDS, DOCUMENTATION, IMAGE ACQUISITION AND VISUALISATION
Keywords: Total station, Laser scanner, 3D camera, Low cost instrument, 2D/3D total station, Tacheometer, pmd-camera, Architectural recording
Abstract. Hardware and software of the universally applicable instrument - referred to as a 2D/3D total station – are described here, as well as its practical use. At its core it consists of a 3D camera – often also called a ToF camera, a pmd camera or a RIM-camera – combined with a common industrial 2D camera. The cameras are rigidly coupled with their optical axes in parallel. A new type of instrument was created mounting this 2D/3D system on a tripod in a specific way. Because of it sharing certain characteristics with a total station and a tacheometer, respectively, the new device was called a 2D/3D total station. It may effectively replace a common total station or a laser scanner in some respects. After a brief overview of the prototype's features this paper then focuses on the methodological characteristics for practical application. Its usability as a universally applicable stand-alone instrument is demonstrated for surveying, recording RGB-coloured point clouds as well as delivering images for documentation and visualisation.
Because of its limited range (10m without reflector and 150 m to reflector prisms) and low range accuracy (ca. 2 cm to 3 cm) compared to present-day total stations and laser scanners, the practical usage of the 2D/3D total station is currently limited to acquisition of accidents, forensic purpuses, speleology or facility management, as well as architectural recordings with low requirements regarding accuracy. However, the author is convinced that in the near future advancements in 3D camera technology will allow this type of comparatively low cost instrument to replace the total station as well as the laser scanner in an increasing number of areas.