Experiences in upgrading of large databases of satellite images

Many technical aspects are involved in the upgrading of satellite image databases: geometric registration, resampling, radiometric adjustment, mosaicking. In this paper, after an overview of all problems, we will focus on the automation of image geocoding. A procedure to perform automatic co-registration of satellite images have been already proposed by the authors (GEOREF), based on an image-to-image registration technique implementing the automatic extraction and matching of corresponding points in a robust way. In case one of the pair of co-registered images is already geocoded, the second one will be as well. Recently the implementation of GEOREF algorithms in an operational environment has been completed and its application to upgrade a database of satellite images has become possible. Furthermore, GEOREF is also able to compute the co-registration of images acquired by different sensors, involving also high resolution and multi-resolution imagery. In this paper, tests concerning high resolution and multi-resolution data fusion from Eros-A1, QuickBird and SPOT-5 satellites are presented.