PARGE: parametric geocoding based on GCP-calibrated auxiliary data

Nearly all current imaging spectroscopy data are obtained by scanning airborne systems. The stability of such systems is always worse than that of spaceborne platforms. Thus, geometric distortions occur due to variations of the flightpath as well as of the attitude of the plane. These distortions cannot be corrected simply by ground control point based traditional georeferencing procedures since the movements cannot be approximated satisfactorily by polynomial transformations of the image. A pixel by pixel calculation has to be performed instead, to account for the position and attitude of the plane during the scanning process. A georeferencing procedure is described which is based on a parametric approach and theoretically allows sub- pixel accuracy even in steep terrain. The current work resulted in a new algorithm and application for parametric geocoding. A ground control point based procedure has been developed to recalibrate the offsets of the attitude data since they usually are given as relative angles. It exactly reconstructs the scanning geometry for each image pixel using position, attitude, and terrain elevation data. The procedure is tested on AVIRIS and on DAIS data and compared to digital topographic data. The geocoding results are of reliable accuracies of down to 1-2 pixels for both data sets.