AUTOMATED PROCEDURES FOR INTEGRATION OF SATELLITE IMAGES AND MAP DATA FOR CHANGE DETECTION: THE ARCHANGEL PROJECT.

The need for automation in the registration of image to image and image to map is widely recognised and work has been going on for some time in both the photogrammetric and remote sensing disciplines. For large scale aerial photography the automation of absolute orientation is tied in with feature recognition but for satellite data operations can take place at a lower level and the problem of relief displacement and occlusions is less. The image to image registration problem is some way to being solved but the image to map problem is much more difficult. The main bottleneck is the identification of points which can be seen on an image and on the corresponding map. This is a manual task at present requiring a considerable amount of time. It is particularly difficult in areas where there is little cultural development and where poor, out of date maps are the only ones available. The ARCHANGEL project is designed to develop a system for the automatic registration of satellite data to maps and this paper describes the system developed and the some of the results achieved. A second difficult and tedious task is the identification of areas where change has taken place. The job of the skilled interpreter is to determine the nature of change, s/he does not wish to spend time finding where the change has occurred. The key aspect of the project is therefore to develop a method which will automatically find common points on the maps and images in any type of area and which will also find areas where change has occurred. The paper will describe the algorithms which have been developed and tested and integrated into a prototype system in an environment called XPECT, developed by Earth Observation Sciences Ltd. Results to date show that the basic algorithms give good results for segmentation, map processing and matching. The algorithms have been tested by the developers and the overall system will be tested by Swedish Space Corporation as end users.