Geometric and Mapping Potential of Worldview-1 Images

The geometric resolution of space images has been improved. With WorldView-1 and GeoEye-1 images taken from space with 0.5m ground sampling distance (GSD) are now available. The Bosphorus Engineering Consultancy Services Inc (BIMTAS), company of Istanbul Greater Municipality ordered a WorldView-1 image, covering large parts of Istanbul city. For the orientation and investigation of the scene accuracy, 29 ground control points (GCPs) could be used. Partially GCPs were handled as independent check points. Even with just one GCP a standard deviation of independent check points in the range of 1.0 GSD was reached. The limited accuracy of the point heights did not allow sub-pixel accuracy, which only was reached in the component direction across the view direction being independent upon the point height. Very similar results have been achieved with a scene in the area of Zonguldak. The information content of the very high resolution space image was tested by mapping all buildings in a sub-area. As reference a building layer of the same area, based on aerial images could be used. In city centres shadows of high buildings make the mapping difficult. Here a local Wallis-filter is helpful. This investigation was supported by analysis of the WorldView-1 stereo pair Morrison, free of charge available in the WEB. An automatic image matching by least squares method was very successful in build up and open, not too mountainous areas, while in very steep parts, located in shadow and covered by forest, the matching result was limited. This is comparable with results achieved with QuickBird and IKONOS stereo scenes.