Improved SAR interferometric processing using local phase-slope correction

SAR interferometry is a technique used to reconstruct detailed terrain height maps. The technique requires two SAR images of the same patch of ground. In order for the interferometric process to succeed, the imaging collection geometry must be within tightly held constraints. The two images are registered and the phases are compared using a 2-dimensional averaging box of several pixels. This phase difference is then proportional to the terrain height at the location of the center of the averaging box. This local averaging process is important because it reduces phase-noise and subsequently produces better height maps. The process, however, assumes that the phase difference is constant over the averaging box. In areas where steep slopes exist, this assumption is violated and the resulting phase difference measurements are in error, resulting in corrupted height maps. This paper presents a technique, which extends the model fo the phase in the averaging box to allow a 2-dimensional linear phase slope to exist. The process estimates the constant phase (the phase that is a measure of the local terrain height) and the phase slope (which is a measure of the terrain slope) in an individual averaging box. Extending the model to include the linear phase slopes greatly improves the constant phase difference estimates, especially in areas of steep terrain. This results in muc more accurate and reliable terrain products. This paper presents a technique, which extends the model of the phase in the averaging box to allow a 2-dimensional linear phase slope to exist. The process estimates the constant phase (the phase that is a measure of the local terrain height) and the phase slope (which is a measure of the terrain slope) in an individual averaging box. Extending the model to include the linear phase slopes greatly improves the constant phase difference estimates, especially in areas of steep terrain. This results in much more accurate and reliable terrain products. This paper demonstrates the viability of the technique on actual SAR data.