Abstract: In the method for geo-referencing of optical remote sensing images of an area of the earth's surface, the geo-referencing is corrected based on an SAR image which is geo-referenced.

Abstract: In the method for geo-referencing of optical remote sensing images of an area of the earth's surface, the geo-referencing is corrected based on an SAR image which is geo-referenced.

Abstract: A method of correcting an object-dependent spectral shift in radar interferograms has two main procedures. In the first, the phase of the interferogram is reconstructed through phase unwrapping and subsequently smoothed for reducing noise. In the second, the two complex-value radar images intended for forming the interferogram are suitably multiplied by a factor derived from the smoothed phase, and are subsequently low-pass-filtered. The spectral shift dependent on the local inclination of the terrain is thus adaptively corrected and the decorrelation caused by the image geometry is extensively eliminated. Particularly in the region of critical, mountainous terrain, the phase noise drops to a very low level.

Abstract: In a method to resolve ambiguities in a phase measurement for application in radar interferometry, a frequency estimation method is used, starting from conjugate complex products of pairs of adjacent pixels in an interferogram. The resolution of these products is subsequently reduced through successive addition or averaging, after which the differential phase of adjacent resolution levels is determined in each resolution level. The sum of the phase differences yields the estimated value for the phase gradient which is then used in a known method, such as the least-squares method, to reconstruct the absolute phase, thus resolving the phase ambiguities. The method according to the invention serves to resolve phase ambiguities in radar interferograms without producing the known distortions produced by the existing methods. The method is also robust at low coherence values as they occur in repeat-pass interferometry where the existing methods fail.

Abstract: In a method for resolving ambiguity in the determination of antenna angle of view and Doppler frequency in synthetic aperture radar (SAR), by evaluating the dependence of the Doppler frequency on the transmitting frequency a skew of the two-dimensional Fourier power spectrum or the two-dimensional autocorrelation function of radar data is measured in that the radar data are subjected to a range Fourier transformation and for the individual range frequencies in a following Doppler centroid estimator a Doppler centroid determination is carried out in the azimuth direction.By this method the pulse repetition frequency ambiguities are eliminated without any demands having to be made on the data acquisition or a high image contrast; this method can therefore be applied to any region of the raw data matrix. Moreover, no azimuth compression is necessary.

Abstract: In a method for correcting range migration in image generation in synthetic aperture radar (SAR) to eliminate the entire range migration or the residual range migration left by a conventional focussing method, prior to the range compression the data are transformed to the range-Doppler domain and there multiplied by a specific two-dimensional phase function; after an additional range Fourier transformatioin the range compression is then carried out with a specifically modified range transfer function and thereafter a range inverse Fourier transformation performed. Furthermore, a corresponding residual phase error is corrected. In addition, the data can if necessary be segmented in range or a range precompression performed.With the method according to the invention the range migration is completely eliminated without having to perform an explicit interpolation.