Automated Geometric Correction of High-resolution Pushbroom Satellite Data

Abstract

In this article, we present the use of the Automatic Ground control points Extraction technique (AGE) for increasing the automation in the geometric correction of high-resolution satellite imagery. The method is based on an image-to-image matching between the satellite data and an already geocoded image (i.e., a digital orthophoto). By using an adaptive least squares matching algorithm which implements a very robust outlier rejection technique, AGE can automatically measure many hundreds of topographic features (TFs) on the images, whose cartographic coordinates are derived from the geocoded image and elevations are extracted from an associated digital elevation model (DEM). The AGE technique has been tested for different high-resolution data: (a) 0.62-meter QuickBird panchromatic data (basic imagery processing level), (b) 2.5-meter SPOT-5/HRG panchromatic supermode data (standard 1B processing level), and (c) 1-meter Ikonos panchromatic data (standard Geo product processing level) collected in the Northern of Italy, both in flat (Torino Caselle test site) and mountain areas (Lecco test site). Regardless the relative image resolution between the satellite and the aerial data (1-meter) and regardless the processing level of the original satellite data, a similar TFs density has been obtained for both the QuickBird and the SPOT-5/HRG data (4.4 GCPs/km 2 and 4.1 GCPs/km 2 ) respectively, with a geomet