Long name | TerraSAR-X/TanDEM-X |
Short name | COS |
Sensor type | Synthetic-aperture radar (SAR) |
Platform | TerraSAR-X, TanDEM-X |
Frequency | 9.65 GHz |
Band (wavelength) | X (3.1 cm) |
Polarization | VV, HH, HV, VH |
Key file name (use to open data set) | *.xml |
Supported file extensions | *.xml, *.cos, *.tif, *.png, *.txt |
Data distributor | German Aerospace Center and ASTRIUM (now EADS) |
Sections |
Data product name and description |
Data product name and description
The acquisition modes of the TerraSAR-X sensor are as described in the following tables.
Mode | Swath width (km) | Resolution (range x azimuth, m)* | Polarization | Description/notes |
---|---|---|---|---|
Spotlight [SL] | 10 | 1.2 x 1.1 (Single polarization) |
Single (VV or HH) |
The Spotlight imaging mode uses phased-array-beam steering in azimuth direction to increase the illumination time; that is, the size of the synthetic aperture, which, however, restricts the image size, scene size, or both. |
High-Resolution Spotlight [HS] | 10 | 0.6 x 1.1 | Single (VV or HH) | Acquisition mode derived from the basic Spotlight [SL] mode. |
Staring Spotlight [ST] | 4 | 0.6 x 0.24 | Single (VV or HH) | Acquisition mode derived from the basic Spotlight [SL] mode. |
StripMap [SM] | 30 (Single polarization) |
1.2 x 3.3 (Single polarization) |
Single (VV or HH) | Acquisition mode derived from the basic Spotlight [SL] mode. |
ScanSAR [SC] | 100 | 1.2 x 18.5 | Single (VV or HH) | The ScanSAR [SC] mode electronicaly steers the antenna elevation to acquire adjacent, slightly overlapping coverage with different incidence angles that are processed into one scene. A swath width of 100 km or greater is achieved by scanning four adjacent ground subswaths with quasi-simultaneous beams, each with a different incidence angle. |
Wide ScanSAR [WS] | 270 | 1.7 x 40 to 3.3 x 40 | Single (VV or HH or HV or VH) | A swath width of up to 270 kilometers is achieved by scanning six adjacent ground subswaths. Due to the switching between the beams, only bursts of SAR echoes are received, resulting in a reduced bandwidth and, therefore, reduced azimuth resolution. |
* Resolution is always single-look complex (SLC) unless noted otherwise.
TerraSAR-X data sets are available for various processing levels, as described in the following table.
Processing level | Acquisition mode | Description/notes |
---|---|---|
1B |
[SL], [HS], [ST] |
Geometric projection: Azimuth - slant range (time domain).
SSC is a single-look product of the focused radar signal. The pixels are spaced equidistant in azimuth (according to the pulse repetition interval PRI=1/PRF) and in slant range (according to the range sampling frequency). The data is represented as complex numbers containing amplitude and phase information. Each image pixel is processed to zero Doppler coordinates in range direction; that is, perpendicular to the flight track. Due to the nature of azimuth/slant-range coordinates, no geocoding is available. |
1B |
[SL], [HS], [ST] |
Geometric projection: Azimuth - ground range (without terrain correction).
MGD is a detected multi-look product with reduced speckle and resolution cells that are approximately square. The image coordinates are oriented along the direction of flight and along ground range. The pixel spacing is equidistant in azimuth and in ground range. With the slant-to-ground-range projection the WGS84 ellipsoid and an average, constant terrain-height value are used. The advantage of this product is the fact that no image rotation to a map coordinate system has been performed and, therefore, interpolation artefacts are avoided. This product is useful, if you want to geocode or orthorectify the imagery. |
1B |
[SL], [HS], [ST] |
Geometric projection: Map geometry with ellipsoidal corrections only (without terrain correction).
GEC is a multi-look detected product, which is resampled and projected to the WGS84 reference ellipsoid assuming one average height. The image is represented in map geometry with ellipsoidal corrections only, and no terrain correction is performed. Available grid formats are Universal Transversal Mercator (UTM) and Universal Polar Stereographic (UPS). Because the ellipsoid correction does not use height information from a digital elevation model (DEM) for geometric correction, the pixel location accuracy varies depending on the local terrain. With other types of relief, the terrain-induced SAR-specific distortions are not corrected and significant location shifts can appear, particularly with strong relief, steep incidence angles, or both. |
1B |
[SL], [HS], [ST] |
Geometric projection: Map geometry with terrain correction using a DEM.
EEC is a multi-look detected product, which is resampled and projected to the WGS84 reference ellipsoid. Image distortions caused by varying terrain height are corrected using an external DEM. The image is represented in map geometry with terrain correction. The available map projections are UTM or UPS. |
TerraSAR-X data is also distributed as various enhanced image products, such as ORISAR, RANSAR, MCSAR, OISAR, and ADMSAR, representing a higher level of processing in radiometric correction and orthorectification, mosaics, subsets and merges. Such products have not been tested by PCI Geomatics.
TerraSAR-X complex data (SSC) is distributed in COSAR format. Detected data (MGD, GEC, EEC) is distributed in GeoTIFF format.
File name | Format | Required | Contents/details |
---|---|---|---|
*.cos | Binary | Yes | DLR-defined COSAR binary format. Contains image data. One file per polarization. |
*.xml | Extensible Markup Language | Yes | Key file name. Main product annotation file. |
GEOREF.xml | Extensible Markup Language | Yes | Georeference file. |
File name | Format | Required | Contents/details |
---|---|---|---|
*.tif | GeoTIFF | Yes | Image data. One GeoTIFF file per polarization. |
*.xml | Extensible Markup Language | Yes | Key file name. Main product annotation file. |
GEOREF.xml | Extensible Markup Language | Yes | Georeference file. |
Returned data for supported format
TerraSAR-X data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file using the key file (*.xml). For optimal processing, use the PCIDSK format.
In the following table, the data structure after it is imported into a PCIDSK file is described (supported processing levels only).
Data product | Data returned | Details |
---|---|---|
SSC (Single) | 1 x [C16S] raster channel (uncalibrated) |
Data can be calibrated in sigma, beta, or gamma nought. |
SSC (Dual) | 2 x [C16S] raster channels (uncalibrated) |
Data can be calibrated in sigma, beta, or gamma nought. |
SSC (Quad) | 4 x [C16S] raster channels (uncalibrated) |
Data can be calibrated in sigma, beta, or gamma nought. |
MGD (Single) | 1 x [16U] raster channel (uncalibrated) |
Data can be calibrated in sigma, beta, or gamma nought. |
MGD (Dual) | 2 x [16U] raster channels (uncalibrated) |
Data can be calibrated in sigma, beta, or gamma nought. |
GEC (Single) |
1 x [16U] raster channel (uncalibrated) |
Data can be calibrated in beta nought. |
GEC (Dual) |
2 x [16U] raster channels (uncalibrated) |
Data can be calibrated in beta nought. |
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