Investigations on the radiometric and geometric characteristics of IKONOS Geo satellite imagery and its use for orthoimage generation and 3D building reconstruction are reported. The paper first starts with an analysis of the radiometric quality of IKONOS Geo images of varying preprocessing and type, focussing on noise, edge quality and definition, and various artefacts. A noise estimation method is presented and results from various IKONOS Geo images, showing an intensity-dependent noise of 2-12 grey levels, which is high considering the effectively 8-9 bit data. Methods will be presented that reduce noise, enhance edges and contrast and optimally reduce 11-bit to 8-bit, without leading to loss of small, but still important, image details. Next, the topic of the geometric potential of IKONOS Geo images using the Rational Polynomial Coefficients (RPCs) and a possible improvement will be discussed. The geometric analysis makes use of stereo images and testfield data provided by the University of Melbourne with 28 well defined and distributed GCPs with 1-2 dm accuracy in object and image space. It will be shown that the RPCs have moderate absolute accuracy (large systematic bias, conforming to the Geo product accuracy specifications of 25 m RMS) but sub-metre relative accuracy. With the help of 4-8 accurate and well-distributed GCPs and a simple translation (bias removal), 0.4-0.5 m and 0.6-0.8 m absolute accuracies in planimetry and height can be achieved with the full
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Baltsavias et al. (2001) studied this question.