Multi-mode ENVISAT ASAR interferometry: techniques and preliminary results

Abstract

The paper focuses on the interferometric capabilities of the current and future SAR systems, like ENVISAT, RADARSAT-2 etc. We introduce a technique to get interferometric surveys by combining two images, coming from any SAR mode, together with a Digital Elevation Mode. The DEM is exploited during the interferogram generation to provide, at one time, an effective noise removal and the compensation for the topographic-dependent fringes. The final product is a "differential" (topography-compensated) interferogram to be used for monitoring over landslides, upswelling, etc.An innovative technique is also discussed to estimate local coherence maps, to be used for classification and change detection. Such technique exploits windows whose shapes and sizes adapt locally to the target features, to attain at one time the highest resolution and the best statistical confidence. Finally, applications involving the various ENVISAT ASAR modes are discussed.

Coherence maps application for InSAR data accuracy improving

“…В ряде источников в числителе не указывается знак модуля, тогда под значением γ понимается ком-плексная когерентность, в этом случае оценка когерентности g вы-числяется как модуль комплексной величины. Применительно к дискретному сигналу используется выражение следующего вида [1,5,9] …”

“…Согласно определению карты когерентности γ представляют со-бой поле коэффициентов корреляции между двумя и более радиоло-кационными изображениями на одну и ту же территорию [1]. Исходя из принятой системы формализации карт когерентности, каждый ее элемент может принимать значения в диапазоне от 0 до 1, причем ну-левое значение яркости соответствует полной декорреляции участка местности, а значение яркости 1, напротив, абсолютной корреляции соответствующих фрагментов.…”

Remote sensing of landslides: An analysis of the potential contribution to geo-spatial systems for hazard assessment in mountainous environments

“…Perhaps a way to overcome the issue of data availability may be by applying the approach proposed by Guarnieri et al (2003) who introduce a technique to obtain interferometric surveys by combining two images, coming from any SAR mode, with a DEM. The DEM is applied during the interferogram generation for noise removal and compensation for the topographic-dependent fringes.…”

“…Opportunities for further research to overcome some of the limitations mentioned in Section 3.2 are open with the availability of new satellite systems (ALOS, TerraSat-X, Radarsat-2, Cosmo/SkyMed), offering higher spatial resolution and higher temporal frequency. Likewise, improved motion mapping in Alpine areas may result from new processing techniques as proposed by Guarnieri et al (2003) to obtain interferometric surveys by combining two images from any SAR mode, or by Ferretti et al (2001), who argue that the PS technique enables spaceborne interferometric measurements over vegetated areas, in addition facilitating the mapping of continuous slow landslide movements. As L-band data is less affected than higher SAR frequencies (Rott, 2004) to decorrelation caused by dense vegetation like alpine forest, the availability of interferometric ALOS imagery (7 m spatial resolution) could provide an avenue for further research of DInSAR or InSAR applications in alpine valleys.…”

Multi-mode SAR Interferometry Processing Research and Implementation

“…However, the problem of synchronization is the main bottleneck for most of the sensors. In addition to interferometry using the same mode data, a meaningful option is to combine burst mode and strip-map mode data to create an interferogram, which can highly improve the availability of SAR data in the aspect of interferometry, and several results can be found in [3,5,7,8]. Considering that the strip-map mode interferometry is much mature, in this paper, we will report our achievements with an emphasis on ScanSAR interferomtry and mix-mode interferometry.…”