VERSION 3.0 IS HERE!! Read the latest version information here

ROI_PAC V3.0, a Repeat Orbit Interferometry Package that allows researchers in the area of topography and surface change to apply Interferometric Synthetic Aperture Radar (InSAR) methods, is now freely available to the community. ROI_PAC, developed primarily to work with ERS data, currently supports ERS-1, ERS-2 and JERS data, and is configurable to work with "strip-mode" data from all existing satellite radar instruments. InSAR is the synthesis of conventional SAR techniques and interferometry techniques that have been developed over several decades in radio astronomy and radar remote sensing, and in recent years has opened entirely new application areas for radar in the earth system sciences, including topographic mapping and geodesy [v. e.g., Thompson et al. 1986, Massonnet and Feigl 1998, Rosen et al. 2000]. The first release of ROI_PAC (V1.0) was made quietly in 2000, and roughly 30 groups in the academic and research community currently use it.

ROI_PAC uses raw radar data, ancillary information from telemetry and navigation solutions, and digital elevation models (DEM; externally provided or interferometrically derived) to produce a variety of derived data products, including the full resolution images, interferograms, phase images measured as principal value and continuously "unwrapped," DEMs, and error estimates. Each of the products is available in its natural radar coordinate system and georeferenced to a DEM. The software computes the interferometric baseline (i.e. the orbital separation of the satellite at the observation times) from the provided navigation solutions, and the refines the estimate to the mm level of precision using the provided DEM and optional deformation model as reference. To remove the topographic signature from an interferogram, ROI_PAC simulates an interferogram from the orbit data and the DEM, and subtracts the phase from the measured interferogram, leaving just the deformation phase. ROI_PAC implements its fundamental algorithms in C and Fortran 90 and drives each executable module with a Perl control script, running on SGI, Sun, and Linux platforms.