抄録
A pixel offset technique is a powerful tool for measurement of local large ground surface displacement. In this technique, a residual offset after coregistration is regarded as an actual surface displacement. Not phase but amplitude is employed for the estimate, which enables us to robustly measure local large displacement of meter order. Here, we review the features of pixel offset method for crustal deformation observation through previous related studies. First we describe the main advantages of this method: the pixel offset analysis 1) can measure large displacement of high spatial gradients, 2) can measure both of the range and azimuth components of the surface displacement, which allows us to infer a 3-D displacement field, 3) is advantageous over an interferometric SAR (InSAR) in insensitivity to change of scattering characteristics of ground / no need for phase unwrapping, and 4) is advantageous over pixel offset using optical sensor in radar’s all-weather detection capability and measurement of vertical component. We next discuss the disadvantages: 1) an artificial range offset correlating with elevation, 2) low spatial resolution, and 3) low precision of measurement. To suppress these demerits, the following approaches are recommended: 1) image coregistration with elevation-dependent correction, 2) selection of SAR data pairs of short perpendicular baseline, 3) use of high spatial resolution SAR data, and 4) cross-correlation calculation using large correlation window size.
