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A Note on the ScanSAR Interferometry module

 

This module supports the processing of:

-Interferometric SAR data (2-pass Interferometry, InSAR) for the generation of Digital Elevation Model (DEM) and related coherence.

-Differential Interferometric SAR data (n-pass Interferometry, DInSAR) for the generation of Land Displacement maps and related coherence.

 

Only the use of data pairs acquired by the PALSAR-2 Full Aperture Scansar and TerrasarX Scansar sensors are supported.

 

A necessary condition to run the ScanSAR interferometric data processing is that the data synchronisation and the baseline are suitable. The interferometric processing is performed on each of the SLC swaths/bursts, which are combined together afterwards.

 

Several processing functions implemented in this module are adapted starting from those available in the Interferometry module and they maintain the same name. Specific technical details, which are not described hereafter, can be retrieved in the Interferometry module Reference Guide.  

 

Assuming appropriate data pairs, the following processing sequences are proposed:

 

1.Digital Elevation Model generation, typically includes the following steps:

–Interferogram Generation.

–Adaptive Filter and Coherence Generation.

–Phase Unwrapping.

–Phase Editing (if required).

–Refinement and Re-flattening.

–Phase to Height Conversion and Geocoding.

 

2.Land Displacement Mapping, typically includes the following steps:

–Interferogram Generation.

–Adaptive Filter and Coherence Generation.

–Phase Unwrapping.

–Phase Editing (if required).

–Refinement and Re-flattening, if required.

–Phase to Displacement Conversion and Geocoding.

 

The following functions, included in this module, support any of the procedures above:

 

 

Interferogram Generation

A multi-looked flattened interferogram - where the phase component related to the topography (or ellipsoid) and the constant phase due to the interferometric acquisition geometry have been subtracted using the previously generated synthetic phase - is created together with the following coregistered data:

 

–Reference and Secondary intensities.

–Synthetic phase.

–Slant range projected Digital Elevation Model.

 

These coregistered products have to be used as input to the further processing steps.

 

Adaptive Filter and Coherence Generation

The phase noise in the flattened interferogram is filtered and the corresponding coherence is generated.

 

Phase Unwrapping

The flattened, filtered interferogram is unwrapped in order to solve the 2π ambiguity.

 

Refinement and Re-flattening

Possible inaccuracies in the satellite orbits as well as the phase offset are corrected.

 

Phase to Height Conversion and Geocoding

The Digital Elevation Model is generated.

 

Phase to Displacement Conversion and Geocoding

The Land Displacement Map is generated.

 

Note that:

 

–SAR Single Look Complex products must be imported (refer to Basic module).

–Reference and Secondary acquisitions must remain in the same order throughout the whole interferometric processing.

–Default setting for selected parameters can be specified in the Preferences panel.

–The SAR Tutorial, which includes basic knowledge on SAR theory and data processing, complements the online help.

–Data geocoded to GEO-GLOBAL cartographic reference system can be automatically displayed into the Google Earth environment by double clicking on the output .kml file.

–Co-ordinate decimal values must be entered using the dot (e.g. 29.30) and not the comma (e.g. 29,30) character.

–The module has been developed by sarmap s.a.

References

 

 

Monti Guarnieri A., P. Guccione, P. Pasquali, and Y.L. Desnos: "Multi-mode ENVISAT ASAR interferometry: Techniques and preliminary results". IEEE Proceedings on Radar, Sonar and Navigation, Vol. 150, No. 3, June, 2003.