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Q. - Why focussed data are sometime affected by Linear Disturbances and Local Artifacts?

 

A. - In some data sets, the presence of scalloping - radiometry anomalies periodically distributed in azimuth direction - or the presence of azimuth ambiguities, ghosts or similar image artifacts can be reported due to discrepancies between the focusing configuration setting and the SAR antenna parameters. The configuration of the focusing algorithm, which is designed in a way to obtain the best signal resolution by exploiting - in azimuth - the largest available bandwidth, depends on specific parameters which are different depending on sensor and acquisition mode; these parameters are stored in sensor-specific files (SARscape installation directory>description_files folder). The sarmap technical team continuously adapts these parameters upon known antenna performance variations; however, in case such artifacts were reported, users are kindly asked to contact us and provide relevant data samples in order to optimize the software performance.

 

Q. - How do SARscape Focusing Algorithms Compare to Data Provider Algorithms? When it can be better to buy preprocessed data (i.e. SLC products) and when it is better to focus the data using SARscape?

 

A. - The quality of the focussed data strongly varies from data provider to data provider. Generally speaking, the SARscape focusing module does a very good job in preserving the phase information; thus for interferometric analysis it could be better to start from RAW data.

 

On the other hand "standard" SLC products, which are directly generated by official providers, enable a better absolute calibration of the amplitude data. The absolute calibration carried out in SARscape is indeed not reliable if the processing starts from RAW data, due to the fact that the program does not take into account the update of several important parameters such as antenna gain, calibration constant and others.

 

Q. - The Interferometric Processing requires SLC products? Is the use of the Focusing module mandatory for the generation of these products?

 

A. - The Single Look Complex data to use as input in the SARscape Interferometric processing chain (e.g. Interferometry Module, Interferometric Stacking Module, ScanSAR Interferometry Module) can be either ordered as standard SLC product and then imported as such into SARscape or ordered as RAW product and then focussed using the dedicated SArscape module. It must be mentioned that not all original raw data are supported by SARscape.