– MODEL DEFORMATION – ACCURACY OF DIGITAL FRAME CAMERAS

Due to legal restrictions, the German hard coal mining company Deutsche Steinkohle AG (DSK) is obliged to conduct a monitoring on surface changes (subsidence) caused by mining activity (e.g. topographic surface, groundwater, water, flora and fauna, soil). To fulfill legal demands and to do this effectively, process chains by use of Photogrammetry, Remote Sensing and Geo Information Systems (GIS) have been established. Photogrammetric methods are used to generate high resolution Digital Elevation Models (DEM) from which in combination with subsidence data geometric changes at the topographic surface are deduced. For mine site areas from about 100 km to 200 km DEMs have to be handled on digital photogrammetric stereo workstations with a height standard deviation of ±10cm. This accuracy up to now could be obtained with analogue wide angle cameras at an image scale of 1:4000 and 80 % end lap together with a high number of ground control points (GCP). More and more digital aerial frame cameras like Intergraph DMC and Vexcel UltraCamD are available for mapping application. DSK decided to order photo flights with the Vexcel UltraCamD because only this camera is able to take images at 80 % end lap with a ground sampling distance (GSD) of 10cm. A vertical accuracy of about ± 8 to 9cm should be reached. Since 2004 three digital photo flights have been made for DSK with the same camera, no. 8. In December 2004 for the stereo plotting of a site plan for a coking plant, in August 2005 a test flight covering 20 km has been made to evaluate the potential of color-infrared images for environmental monitoring purposes and in March 200