The All Digital Photogrammetric Workflow: Redundancy and Robustness

Digital aerial cameras, among them the UltraCamD, the new large-format digital aerial camera of Vexcel Imaging, are ready to replace the aerial film camera. This is reason enough to highlight the improvements in radiometric and geometric quality that such a camera provides. Is it the ability to resolve dark shadows, is it the ability to simultaneously register panchromatic, true color and false color infrared or is it the ability to increase the forward overlap at no extra costs for film, development and scanning, we are convinced, that with such digital cameras, a novel strategy of source image acquisition can be considered. Aerial photogrammetry has long used a convention of 60% forward overlap and 20% sidelap, in order to provide for stereo compilation and the generation of products such as digital terrain models (DTM) and orthophotos.We argue that digital cameras can be used to challenge standard photogrammetric conventions: no longer is film grain an issue, high radiometric resolution at a 12 bit level and no longer is the number of images the predominant driver in defining a photogrammetric project. Increased redundancy and higher overlaps provide a key to optimized levels of accuracy, automation and robustness in a production environment. The design of the UltraCamD with its parallel architecture permits a very high framing rate, thus affording flexibility to select a forward overlap of up to 90%. Further, the role of parallel architecture in sensor design, together with efficient data transfer and storage options, is discussed. If this change in the strategy of image acquisition take place, an enhancement of automation and robustness in the photogrammetric production can be expected.