# SAR_CEOS – CEOS SAR Image

Driver short name

SAR_CEOS

Driver built-in by default

This driver is built-in by default

This is a read-only reader for CEOS SAR image files. To use, select the main imagery file.

This driver works with most Radarsat, JERS-1 and ERS data products, including single look complex products; however, it is unlikely to work for non-Radar CEOS products. The simpler CEOS driver is often appropriate for these.

This driver will attempt to read 15 lat/long GCPS by sampling the per-scanline CEOS superstructure information. In the case of products from the Alaska Satellite Facility, it will obtain corner coordinates from either the map projection record in the case of ScanSAR products, or the facility data record for non-ScanSAR products. It also captures various pieces of metadata from various header files, including:

    CEOS_LOGICAL_VOLUME_ID=EERS-1-SAR-MLD
    CEOS_FACILITY=CDPF-RSAT
    CEOS_PROCESSING_FACILITY=APP
    CEOS_PROCESSING_AGENCY=CCRS
    CEOS_PROCESSING_COUNTRY=CANADA
    CEOS_SOFTWARE_ID=APP 1.62
    CEOS_ACQUISITION_TIME=19911029162818919
    CEOS_SENSOR_CLOCK_ANGLE=  90.000
    CEOS_ELLIPSOID=IUGG_75
    CEOS_SEMI_MAJOR=    6378.1400000
    CEOS_SEMI_MINOR=    6356.7550000

The SAR_CEOS driver also includes some support for SIR-C and PALSAR polarimetric data. The SIR-C format contains an image in compressed scattering matrix form, described here. GDAL decompresses the data as it is read in. The PALSAR format contains bands that correspond almost exactly to elements of the 3x3 Hermitian covariance matrix- see the ERSDAC-VX-CEOS-004A.pdf document for a complete description (pixel storage is described on page 193). GDAL converts these to complex floating point covariance matrix bands as they are read in. The convention used to represent the covariance matrix in terms of the scattering matrix elements HH, HV (=VH), and VV is indicated below. Note that the non-diagonal elements of the matrix are complex values, while the diagonal values are real (though represented as complex bands).

- Band 1: Covariance_11 (Float32) = HH*conj(HH)

- Band 2: Covariance_12 (CFloat32) = sqrt(2)*HH*conj(HV)

- Band 3: Covariance_13 (CFloat32) = HH*conj(VV)

- Band 4: Covariance_22 (Float32) = 2*HV*conj(HV)

- Band 5: Covariance_23 (CFloat32) = sqrt(2)*HV*conj(VV)

- Band 6: Covariance_33 (Float32) = VV*conj(VV)

The identities of the bands are also reflected in the metadata.

NOTE: Implemented as `gdal/frmts/ceos2/sar_ceosdataset.cpp`.

## Driver capabilities

Supports Georeferencing

This driver supports georeferencing

Supports VirtualIO

This driver supports virtual I/O operations (/vsimem/, etc.)