Accuracy assessment of an IKONOS derived DSM over urban and suburban area

The availability of IKONOS stereo pairs has made it possible to generate Digital Surface Models of IKONOS data. Though it is possible to obtain a DSM from two images with a different viewing angle on the same area, it is preferred to work with products ordered as stereo. Such stereo pairs have images that are made in the same orbital pass, resulting in a much better geometry of the stereo model. In this paper the accuracy of an IKONOS derived DSM of urban areas is assessed, based on DSMs from aerial photography and laser scanning. The quality and accuracy of a DSM derived from IKONOS stereo pairs has been assessed for test zones in two cities, Ghent and Liege. The test zones are characterized by a typical urban morphology (city center, residential, industry). The accuracy has been assessed for each of the different types of urban morphology in the study areas. An error surface is obtained by calculating the difference between the generated IKONOS surface models and reference surface models. This surface is used as a measure for the accuracy of the IKONOS surface model. Reference surface models from different origins are used (aerial photography, lidar, large scale 3D database). For the test zones in Liege, the relation between the DSM accuracy and different land cover types is studied in detail. Also the relation between DSM error and the topography will be investigated.