Pairs Of Synthetic Aperture Radar Images Research Articles

Monitoring crustal deformation by GPS and InSAR in the three gorge area

The on-going Three Gorges Project (TGP) aims to build one of the largest hydropower stations in the world. Previous investigations have concluded that the reservoir is likely to induce medium-to-intense earthquakes. 23 GPS stations have been established to maintain a geodetic and seismological monitoring network around the reservoir to monitor seismicity and crustal deformation, and to facilitate mitigation activities in case an intense earthquake occurs. The velocity of GPS site was derived from 3 repeated GPS surveys. Meanwhile, another effort has been made to investigate the feasibility of application of satellite interferometric synthetic aperture radar (InSAR) techniques in detecting crustal deformation possibly caused by impoundment of the Three Gorges Reservoir. It has been made to derive digital elevation models (DEM) using European Remote Sensing (ERS) synthetic aperture radar (SAR) imagery. Pairs of ERS SAR images in raw format are processed to generate digital elevation models. This effort will help us evaluate the accuracy of the InSAR techniques for further derivation of background deformation patterns and future detection of reservoir-induced crustal deformation in the area.

Study of high SAR backscattering caused by an increase of soil moisture over a sparsely vegetated area: Implications for characteristics of backscattering

We used interferometric methods on a pair of repeat-pass ERS-1 synthetic aperture radar (SAR) images to study soil moisture changes over sparsely vegetated targets. The intensity of the SAR image acquired at one time was higher than that of an image acquired at an earlier time. We used a correlation image computed from the SAR image pair to study the cause of the observed changes in SAR intensity. Because a reduction of correlation over areas with intensity changes was not observed, we interpreted the intensity changes as not being caused by changes in roughness/structure, but by a change in soil moisture owing to rainfall. An increase in soil moisture ranging from 5% to 20% is the most likely explanation for the increase of intensity. These analyses imply that both intensity and phase information should be used in SAR change detection applications.

Image-Analysis Techniques for Determination of Morphology and Kinematics in Arctic Sea Ice

The synthetic aperture radar (SAR) data have been used to study sea ice with respect to its motion and formation/deformation. With the prospect of the Alaska SAR Facility development in the near future, there is a great need for robust and efficient sea-ice analysis techniques. This paper presents a sea-ice motion analysis technique that can be used for (1) local motion analysis of a selected ice patch and (2) a global ice motion over the entire image area. Though there are several sea-ice motion tracking techniques, they do not provide the required operational speed or robustness. In order to meet the operational speed requirement (over fifty images per day), we have developed a sea-ice motion analysis technique which requires very little human interaction and much simplified computation. The proposed technique uses a subset of easily distinguishable features to predict global motion characteristics and apply template matching over a predicted search area. We applied the developed technique to two pairs of SEASAT SAR images, one pair with a minor motion of “ice pack” and another with a larger and discontinuous motion of “fast ice”. The two major achievements of the new approach are: first, development of a set of computer-aided tools for feature selection and registration and, secondly, implementation of an optimal search strategy for automatic template matching via a motion prediction model.

Image-Analysis Techniques for Determination of Morphology and Kinematics in Arctic Sea Ice

The synthetic aperture radar (SAR) data have been used to study sea ice with respect to its motion and formation/deformation. With the prospect of the Alaska SAR Facility development in the near future, there is a great need for robust and efficient sea-ice analysis techniques. This paper presents a sea-ice motion analysis technique that can be used for (1) local motion analysis of a selected ice patch and (2) a global ice motion over the entire image area. Though there are several sea-ice motion tracking techniques, they do not provide the required operational speed or robustness. In order to meet the operational speed requirement (over fifty images per day), we have developed a sea-ice motion analysis technique which requires very little human interaction and much simplified computation. The proposed technique uses a subset of easily distinguishable features to predict global motion characteristics and apply template matching over a predicted search area. We applied the developed technique to two pairs of SEASAT SAR images, one pair with a minor motion of “ice pack” and another with a larger and discontinuous motion of “fast ice”. The two major achievements of the new approach are: first, development of a set of computer-aided tools for feature selection and registration and, secondly, implementation of an optimal search strategy for automatic template matching via a motion prediction model.