Sentinel-1 support in the GAMMA Software

Abstract

First results using the new Sentinel-1 SAR look very promising but the special interferometric wideswath data acquired in the TOPS mode makes InSAR processing challenging. The steep azimuth spectra ramp in each burst results in very stringent co-registration requirements. Combining the data of the individual bursts and sub-swaths into consistent mosaics requires careful "book-keeping" in the handling of the data and meta data and the large file sizes and high data throughputs require also a good performance. Considering these challenges good support from software is getting increasingly important. In this contribution we describe the Sentinel-1 support in the GAMMA Software, a high-level software package used by researchers, service providers and operational users in their SAR, InSAR and PSI work.

Monitoring Cultural Heritage Sites with Advanced Multi-Temporal InSAR Technique: The Case Study of the Summer Palace

“…In this study, calibrated single-look complex (SLC) images were firstly co-registered referring to the master image (20091120), resulting in high accuracy with a standard deviation limited to 0.02 pixels. Then, massive historic architectures in the Summer Palace were extracted as PS candidates using the indexes of strong backscattering and low intensity-variability [17]. The spatial distribution of PSs was usually uneven due to the diversity of observed features.…”

“…The minimized phase noise from the spatial-temporal decorelation in conjunction with the relaxed data requirement of PSInSAR and/or SqueeSAR techniques can be achieved by utilizing the small-baseline strategy. Basic interferometric processing (including SLC SAR image calibration, SAR image co-registration, multi-looking, PS candidate extraction, interferogram generation, removal of topography and flat earth phase and 3D phase unwrapping) was carried out using GAMMA software [17]. For other stages of the interferometric processing, programs implemented in MATLAB and C++ were applied (for more technical details, please refer to [16]).…”

Continent-Wide 2-D Co-Seismic Deformation of the 2015 Mw 8.3 Illapel, Chile Earthquake Derived from Sentinel-1A Data: Correction of Azimuth Co-Registration Error

“…The 90 m SRTM DEM (v4.1) is used to estimate the initial look-up table [24] and remove the topographic phase. Thanks to the precise orbital state vector [6], an accuracy of a few pixels could be achieved [16] in the preliminary co-registration using orbital information. Then, the CC method is used to estimate the image offsets from evenly-distributed 64ˆ192 (rangeˆazimuth) tie-points with matching windows size of 128ˆ256 (rangeˆazimuth) pixels.…”

“…To meet the requirement and to counteract the topographic effect, the co-registration of wideswath SLC images of S1A TOPS SLC [16] generally involves a sequentially DEM-assisted method (Step 1), conventional Cross-Correlation (CC) (Step 2) method, and a SD method (Step 3). Our ISD method can be easily embedded into the S1A SLC co-registration procedure for multiple S1A TOPS frames.…”

“…The Doppler Centroid of TOPS SAR data varies strongly along tracks, so a co-registration accuracy of at least 0.001 SLC pixel is required to eliminate the effect [7]. Currently, the Spectral Diversity (SD) [14] method and the enhanced SD (ESD) [15], implemented in GAMMA [16] or GMTSAR [17], could perform well for a single frame data case, but cannot resolve the problem of co-registering multiple S1A TOPS data frames well.…”