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SICD is an open, standardized specification for SAR data developed and maintained by the US National Geospatial Intelligence Agency (NGA). The full documentation is available here.

Unlike CPHD, SICD files have been processed through an "image formation algorithm" and associated metadata has been adapted to meet a generic level of "independence" from the sensor that generated it. Therefore, while SICD files are more "opinionated" than CPHD, they are also less idiosyncratic.

The NGA's motivation for creating the SICD standard was to enable integration of data from multiple disparate SAR systems using a common processing toolset and downstream analytical workflow. As more commercial providers adopt the SICD standard, end-users will benefit from the ability to create generic tools rather than having to build custom plugins for every vendor.
Umbra uses the SICD standard to provide complex phase data in a more refined state than it does with its CPHD product. The "Polar Format Algorithm" (PFA) is used for image formation.

Data Structure
Umbra produces complex data according to the SICD standard embedded inside of a National Imagery Transmission Format (NITF) file. NITF is an open specification created and maintained by the US National Geospatial Intelligence Agency (NGA) and described elsewhere in the help center here. For full documentation on the NITF file structure, we recommend visiting the official documentation on the NGA's website here

SICD data is constituted of two complementary parts inside of a NITF container:
  • A block of complex image pixel data containing the phase history of the SAR data ("complex" meaning both the real and imaginary components of the phase data)
  • A metadata description of the data adhering to a strict XML structure
The complete SICD documentation is available in three complementary volumes: