Gamma DIFF&GEO: Reference Manual

DIFF&GEO File Formats

Single look complex SAR data (<YYYYMMDD>.slc)

Two formats for SLC data are supported.

In the first format the SLC data are in fcomplex floating point representation, each complex sample consists of two 4 byte (32-bit) floating point numbers, real and imaginary part. There is no file header, or zero padding of the data. Each record corresponds to a single range line. The number of samples/line and the number of lines is specified in the SLC parameter file SLC_par.

In the second format the SLC data are in short integer representation, each complex sample consists of two short integer (2 byte, 16-bit) numbers, real and imaginary part. The second format is also the format provided by ESA Processing Facilities (PAFs). Real and imaginary part of the SLC data are in 2 byte integer format. File header, or zero padding of the data as described in the CEOS leader file. Each record corresponds to a single range line. The number of samples/line and the number of lines is specified in the SLC parameter file SLC_par.

Float format (32-bit) multi-look intensity SAR data (<YYYYMMDD>.mli)

The MLI data are in floating point representation, each 4 byte floating point number, corresponds to a SAR multi-look intensity value (in slant range geometry). There is no file header, or zero padding of the data. Each record corresponds to a single range line. The number of samples/line and the number of lines is specified in the MLI parameter file which has the same format as the SLC parameter file SLC_par.

Float format (32-bit) multi-look intensity SAR data in ground-range geometry (<YYYYMMDD>.grd)

The GRD data are in floating point representation, each 4 byte floating point number, corresponds to a SAR multi-look intensity value (in ground-range geometry). There is no file header, or zero padding of the data. Each record corresponds to a single range line. The number of samples/line and the number of lines is specified in the GRD parameter file which has the same format as the SLC parameter file SLC_par.

Real valued "Precision Image" PRI data product provided by ESA (<YYYYMMDD>.mli)

The PRI data are in short integer representation, each 2 byte short integer, corresponds to a SAR multi-look magnitude value (in ground-range geometry). There is typically a 12 byte line header. Each record corresponds to a single range line. The number of samples/line and the number of lines is specified in the PRI parameter file which is generated from the CEOS leaderfile and which has the same format as the SLC parameter file SLC_par, except that the indicated range values correspond to ground-ranges and not to slant-ranges.

Complex valued geocoding lookup table used by GAMMA Software (<>.utm_to_rdc, <>.eqa_to_grd, etc.)

The geocoding lookup table used by GAMMA Software is a binary file in fcomplex representation, each complex sample consists of two 4 byte floating point numbers, real and imaginary part. Each complex sample indicates the corresponding transformed coordinate with the real part indicating the x / col pixel number and the imaginary part indicating the y / row pixel number. Geocoding lookup tables are generated using the programs gc_map, gc_map_grd, gec_map, gec_map_grd, and gc_insar and are used for the geocoding resampling transformation done with the programs geocode_back and geocode. The number of samples/line and the number of lines is specified in the DEM/MAP parameter file (DEM_par of the corresponding DEM/MAP segment.

Complex data (.int, .flt, .sm, .diff)

fcomplex-valued data (for example the interferogram) saved as pairs of 4-byte floating point numbers (real part followed by imaginary part). Image width and height correspond to the number of range and azimuth pixels, respectively. No header or zero-padding is used. Image width and height are given in the ISP processing/offset parameter file.

Real data (.mli, .cc, .unw, .hgt, .rmli, .rhgt, ...)

Real-valued data saved as 4-byte floating point numbers. Image width and height correspond to the number of range and azimuth pixels, respectively. No header or zero-padding is used. Image width and height are given in the ISP processing/offset parameter file.