Abstract-Synthetic aperture radar (SAR) interferometric data offer the opportunity to measure temperate glacier surface topography and displacement. The increase of the resolution provided by the most recent SAR systems has some critical implications. For instance, a reliable estimate of the phase gradient can only be achieved by using interferogram local frequencies. In this paper, an original two-step method for estimating local frequencies is proposed. The 2-D phase signal is considered to have two deterministic components corresponding to low-resolution (LR) fringes and high-resolution (HR) patterns due to the local microrelief, respectively. The first step of the proposed algorithm consists in the LR phase flattening. In the second step, the local HR frequencies are estimated from the phase 2-D autocorrelation function computed on adaptive neighborhoods. This neighborhood is the set of connected pixels belonging to the same HR spatial feature and respecting the "local stationarity" hypothesis. Results with both
For merging Synthetic Aperture Radar (SAR) with georeferenced data, one usually uses processing software to orthorectify the SAR images in order to add them in a GIS. Nevertheless, this projection involves an important alteration of the information of SAR images and are often specific to some particular SAR sources. Moreover, the transformation of radarcoding data from a GIS into the radar geometry allows the use of different information sources to improve the analysis of SAR images and the result interpretation. In this paper, we propose a simple and efficient method to build two couples of Look Up Tables (LUT) allowing to code data in ground or radar geometry. This approach is applied to a high relief area in the Alps, where satellite and airborne SAR images are used for glacier evolution monitoring.
Abstract-SAR interferometric data offers the opportunity to measure temperate glacier surface topography and displacement between the two acquisitions. Recently, reliable estimates of the phase gradient given by interferogram local frequencies become mandatory with the increase of the SAR resolution. In this paper, an original 2-step method for estimating local frequencies is proposed. The 2D phase signal is considered to have two deterministic components corresponding to low-resolution fringes and high-resolution patterns due for instance to the micro-relief. The first step of the proposed algorithm consists in the low-resolution phase flattening. In the second step the local high-resolution frequencies are estimated from the phase auto-correlation functions computed on adaptive neighborhoods using only the pixels which belong to the same HR spatial feature and respect the "local stationarity" hypothesis. Results with both real ERS 1/2 tandem and simulated TerraSAR-X interferograms are presented to illustrate the potential of the proposed method.
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