Sina Montazeri

Geodetic SAR Tomography

In this paper, we propose a framework referred to as “geodetic synthetic aperture radar (SAR) tomography” that fuses the SAR imaging geodesy and tomographic SAR inversion (TomoSAR) approaches to obtain absolute 3-D positions of a large amount of natural scatterers. The methodology is applied on four very high resolution TerraSAR-X spotlight image stacks acquired over the city of Berlin. Since all the TomoSAR estimates are relative to the same reference point object whose absolute 3-D positions are retrieved by means of stereo SAR, the point clouds reconstructed using data acquired from different viewing angles can be geodetically fused. To assess the accuracy of the position estimates, the resulting absolute shadow-free 3-D TomoSAR point clouds are compared with a digital surface model obtained by airborne LiDAR. It is demonstrated that an absolute positioning accuracy of around 20 cm and a meter-order relative positioning accuracy can be achieved by the proposed framework using TerraSAR-X data.

Three-Dimensional Deformation Monitoring of Urban Infrastructure by Tomographic SAR Using Multitrack TerraSAR-X Data Stacks

Differential synthetic aperture radar tomography (D-TomoSAR), similar to its conventional counterparts such as differential interferometric SAR and persistent scatterer interferometry, is only capable of capturing 1-D deformation along the satellites line of sight. In this paper, we propose a method based on L1-norm minimization within local spatial cubes to reconstruct 3-D displacement vectors from TomoSAR point clouds available from at least three different viewing geometries. The methodology is applied on two pairs of cross-heading-combination of ascending and descending-TerraSAR-X (TS-X) spotlight image stacks over the city of Berlin. The linear deformation rate and the amplitude of seasonal deformation are decomposed, and the results from two test sites with remarkable deformation pattern are discussed in detail. The results, to our knowledge, demonstrate the first attempt for motion decomposition using TomoSAR data from multiple viewing geometries.

Automatic Detection and Positioning of Ground Control Points Using TerraSAR-X Multiaspect Acquisitions

Geodetic stereo synthetic aperture radar (SAR) is capable of absolute 3-D localization of natural persistent scatterers, which allows for ground control point (GCP) generation using only SAR data. The prerequisite for the method to achieve high-precision results is the correct detection of common scatterers in SAR images acquired from different viewing geometries. In this contribution, we describe three strategies for automatic detection of identical targets in SAR images of urban areas taken from different orbit tracks. Moreover, a complete workflow for automatic generation of large number of GCPs using SAR data is presented and its applicability is shown by exploiting TerraSAR-X high-resolution spotlight images over the city of Oulu, Finland, and a test site in Berlin, Germany.

SAR ground control point identification with the aid of high resolution optical data

Only until recently, it has been demonstrated that absolute localization with centimeter accuracy can be achieved for manually matched Persistent Scatterer (PS)s from TerraSAR-X images acquired from cross-heading geometries [1]. This paper describes an automatic algorithm for absolute localization of natural PSs in SAR images, where the detection of potential PSs is aided by high resolution optical data. As the focus of the study is on urban area, the target detection part relies on identification of lamp posts using template matching. These targets are, most probably, the only ones visible in SAR images acquired from both ascending and descending orbits. Thus, the methodology includes identification of lamp posts from high resolution optical data and retrieves the precise absolute three-dimensional coordinates of the points from corrected TerraSAR-X timing measurements using the stereo SAR method [1]. Preliminary results for a test site in the city of Berlin acquired from TerraSAR-X high resolution spotlight mode are shown.

Automatic positioning of SAR ground control points from multi-aspect TerraSAR-X acquisitions

Geodetic stereo SAR is capable of absolute 3-D localization of natural persistent scatterers (PS)s which allows for Ground Control Point (GCP) generation using only SAR data. The prerequisite for the method to achieve high precision results is the correct detection of common scatterers in SAR images acquired from different viewing geometries. In this contribution, we describe three strategies for automatic detection of identical point targets in SAR images of urban areas taken from different orbit tracks. Moreover, a complete work-flow for automatic generation of large number of GCPs using SAR data is presented and its applicability is shown by exploiting TerraSAR-X high resolution spotlight images over the city of Oulu, Finland and a test site in Berlin, Germany.

Geodetic TomoSAR — Fusion of SAR imaging geodesy and TomoSAR for 3D absolute scatterer positioning

In this paper, we propose a framework referred to as “geodetic TomoSAR“ that fuses the SAR image geodesy and TomoSAR approaches to obtain absolute 3D positions of a large amount of natural scatterers. The methodology is applied on four Very High Resolution (VHR) TerraSAR-X spotlight image stacks acquired over the city of Berlin. Since the TomoSAR estimates are referred to the identical reference point whose absolute 3D positions are retrieved by means of Stereo-SAR, the point clouds from ascending and descending orbits are automatically fused. To assess the accuracy of the position estimates, the resulting absolute shadow-free 3D TomoSAR point clouds are compared to a DSM obtained by airborne LiDAR.