MEDIUM-FORMAT CAMERAS AND THEIR USE IN TOPOGRAPHIC MAPPING
- Aalborg University, Dept. of Planning, Fibigerstraede 11, 9220 Aalborg, Denmark
Keywords: Camera, Imagery, Performance, Impact Analysis, Application, DEM/DTM, Orthoimage, Updating
Abstract. Based on practical experiences with large-format aerial cameras the impact of new medium-format digital cameras on topographic mapping tasks is discussed. Two new medium-format cameras are investigated with respect to elevation accuracy, area coverage and image quality. The produced graphs and tables show the potential of these cameras for general mapping tasks. Special attention is given to the image quality of the selected cameras. Applications for the medium-format cameras are discussed. The necessary tools for selected applications are described. The impact of sensors for georeferencing, multi-spectral images, and new matching algo-rithms is also dealt with. Practical investigations are carried out for the production of digital elevation models. A comparison with large-format frame cameras is carried out. It is concluded that the medium-format cameras have a potential for mapping of smaller areas and will be used in future in true orthoimage production, corridor mapping, and updating of maps. Their small dimensions and low weight allow installation in small airplanes, helicopters, and high-end UAVs. The two investigated medium-format cameras are low-cost alternatives for standard mapping tasks and special applications. The detection of changes in topographic databases and DTMs can be carried out by means of those medium-format cameras which can image the same area in four bands of the visible and invisible spectrum of light. Medium-format cameras will play an important role in future mapping tasks.