Module eoreader.products.sar

SAR products.

SAR data

Implemented SAR satellites

Satellites Class Product Types Use archive
Sentinel-1 S1Product SLC & GRD Yes
COSMO-Skymed CskProduct DGM & SCS, (others should also be OK) No
TerraSAR-X TsxProduct MGD (SSC should be OK) No
RADARSAT-2 Rs2Product SGF (SLC should be OK) Yes

Warning

Satellites products that cannot be used as archived have to be extracted before use.

SAR Bands

According to what contains the products, allowed SAR bands are:

You also can load despeckled bands:

DEM bands

These bands need a valid worldwide DEM path positioned thanks to the environment variable EOREADER_SAR_DEFAULT_RES

  • DEM
  • SLOPE

See here for more information. SAR satellites can only load DemBandNames.DEM and DemBandNames.SLOPE bands as the sun position does not impact SAR data. The SLOPE band is computed with the gdaldem tool.

These bands need a valid worldwide DEM path positioned thanks to the environment variable EOREADER_SAR_DEFAULT_RES.

Default resolution

The default resolution of SAR products depends on their type. Complex data are always converted back to ground range to be used.

The product resolution is read in the metadata file if possible, so the following values are given as hints:

Sentinel-1

| Sentinel-1 | Single Look Complex (SLC) |Ground Range Detected (GRD)
Full Resolution (FR) | Ground Range Detected (GRD)
High Resolution (HR) | Ground Range Detected (GRD)
Medium Resolution (MR)| |— | — | — | — | —| |StripMap (SM) | 1.5x3.6 m to 3.1x4.1 m | 3.5m | 10.0m | 40.0m| |Interferometric Wide swath (IW) | 2.3x14.1 m | | 10.0m | 40.0m| |Extra-Wide swath (EW) | 5.9x19.9 m | | 25.0m | 40.0m| |Wave (WV) | 1.7x4.1 m and 2.7x4.1 m | | | 25.0m|

COSMO-Skymed

| COSMO-Skymed | Single-look Complex Slant (SCS) | Detected Ground Multi-look (DGM)
Geocoded Ellipsoid Corrected (GEC)
Geocoded Terrain Corrected (GTC)| |— | — | —| |Spotlight
Mode-2 (S2) | 1.1-0.9x0.91m | 1.0m| |StripMap
Himage (HI) | 3.0-2.6x2.4-2.6m | 5.0m| |StripMap
PingPong (PP) | 11-10x9.7m | 20.0m| |ScanSAR
Wide Region (WR) | 13.5x23m | 30.0m| |ScanSAR
Huge Region (HR) | 13.5x38.0m | 100.0m|

TerraSAR-X

| TerraSAR-X | Single-look Slant Range (SSC) | Multi Look Ground Range (MGD)
Geocoded Ellipsoid Corrected (GEC)
Enhanced Ellipsoid Corrected (EEC)
Spatially enhanced
(high resolution, SE)| Multi Look Ground Range (MGD)
Geocoded Ellipsoid Corrected (GEC)
Enhanced Ellipsoid Corrected (EEC)
Radiometrically enhanced
(high radiometry, RE)| |— | — | — | —| |StripMap (SM)
Single-Pol | 0.9x2.0m | 1.5m or 1.25m | 4.0m or 3.25m| |StripMap (SM)
Dual-Pol | 0.9x2.5m | 3.0m | 5.5m or 4.5m| |High Resolution Spotlight (HS)
Single-Pol | 0.9x0.8m | 1.5m or 0.5m | 2.0m or 1.5m| |High Resolution Spotlight (HS)
Dual-Pol | 0.9x1.5m | 1.5m or 1.0m | 3.0m or 2.0m| |Spotlight (SL)
Single-Pol | 0.9x1.3m | 1.5m or 0.75m | 3.0m or 1.75m| |Spotlight (SL)
Dual-Pol | 0.9x2.6m | 3.5m or 3.4m | 8.5m or 5.5m| |Staring Spotlight (ST)
Single-Pol | 0.5x0.2m | 0.4m or 0.2m | 0.8m or 0.4m| |ScanSAR (SC)
Four Beams | 0.9x13m | | 8.25m| |ScanSAR (SC)
Six Beams | 1.4x?m | | 15.0m|

RADARSAT-2

| RADARSAT-2 | Single-look complex (SLC) | SAR georeferenced extra(SGX) | SAR georeferenced fine (SGF) | SAR systematic geocorrected (SSG) | SAR precision geocorrected (SPG) | ScanSAR narrow beam (SCN) | ScanSAR wide beam (SCW) | ScanSAR fine (SCF) | ScanSAR sampled (SCS)| |— | — | — | — | — | — | — | — | — | —| |Spotlight | 1.3x0.4m | 1.0 or 0.8x1/3m | 0.5m | 0.5m | 0.5m | | | | | |Ultra-Fine | 1.3x2.1m | 1.0x1.0 or 0.8x0.8m | 1.56m | 1.56m | 1.56m | | | | | |Wide Ultra-Fine | 1.3x2.1m | 1.0m | 1.56m | 1.56m | 1.56m | | | | | |Multi-Look Fine | 2.7x2.9m | 3.13m | 6.25m | 6.25m | 6.25m | | | | | |Wide Multi-Look Fine | 2.7x2.9m | 3.13m | 6.25m | 6.25m | 6.25m | | | | | |Extra-Fine | Full Res: 2.7x2.9m
Fine Res: 4.3x5.8m
Full Res: 7.1x5.8m
Wide Res: 10.6x5.8m | 1 look: 2.0m
4 looks: 3.13m
28 looks: 5.0m | 1 look: 3.13m
4 looks: 6.25m
28 looks: 8.0m | 3.13m | 3.13m | | | | | |Fine | 4.7x5.1m | 3.13m | 6.25m | 6.25m | 6.25m | | | | | |Wide-Fine | 4.7x5.1m | 3.13m | 6.25m | 6.25m | 6.25m | | | | | |Standard | 8.0 or 11.8x5.1m | 8.0m | 12.5m | 12.5m | 12.5m | | | | | |Wide | 11.8x5.1m | 10.0m | 12.5m | 12.5m | 12.5m | | | | | |Extended High | 11.8x5.1m | 8.0m | 12.5m | 12.5m | 12.5m | | | | | |Extended Low | 8.0x5.1m | 10.0m | 12.5m | 12.5m | 12.5m | | | | | |Fine Quad-Pol | 4.7x5.1m | 3.13m | 3.13m | 3.13m | 3.13m | | | | | |Wide Quad-Pol | 4.7x5.1m | 3.13m | 3.13m | 3.13m | 3.13m | | | | | |Standard Quad-Pol | 8.0 or 11.8x5.1m | 8.0x3.13m | 8.0x3.13m | 8.0x3.13m | 8.0x3.13m | | | | | |Wide Standard Quad-Pol | 8.0 or 11.8x5.1m | 8.0x3.13m | 8.0x3.13m | 8.0x3.13m | 8.0x3.13m | | | | | |ScanSAR Narrow | | | | | | 25.0m | | 25.0m | 25.0m| |ScanSAR Wide | | | | | | | 50.0m | 50.0m | 50.0m| |Ship (Detection of vessels) | | | | | | | | 40.0m | 20.0m| |Ocean Surveillance | | | | | | | | 50.0m | 35.0x25.0m|

GPT graphs

You can change the SAR GPT graphs used by setting the following environment variables:

  • EOREADER_PP_GRAPH: Environment variables for pre-processing graph path.
  • EOREADER_DSPK_GRAPH: Environment variables for despeckling graph path

Warning

For performance reasons, the Terrain Correction step is done before the Despeckle step. Indeed this step is very time-consuming and better done one time on the raw image than two times on both the raw and the despeckled image. Even if this is not the regular way of handling SAR data, this shouldn't really affect the quality of any extraction done after that.

What to know if you are changing a graph

Those graphs should have a reader and a writer on this model:


<graph id="Graph">
    <version>1.0</version>
    <node id="Read">
        <operator>Read</operator>
        <sources/>
        <parameters class="com.bc.ceres.binding.dom.XppDomElement">
            <file>$file</file>
        </parameters>
    </node>
    <node id="Write">
        <operator>Write</operator>
        <sources>
            <sourceProduct refid="????"/>
        </sources>
        <parameters class="com.bc.ceres.binding.dom.XppDomElement">
            <file>$out</file>
            <formatName>BEAM-DIMAP</formatName>
        </parameters>
    </node>
</graph>

Warning

Pay attention to set $file and $out and leave the BEAM-DIMAP file format. The first graph must orthorectify your SAR data, but should not despeckle it. The second graph is precisely charged to do it.

The pre-processing graph should also have a <code>Terrain Correction</code> step with the following wildcards that are set automatically in the module:

- `$res_m`: Resolution in meters
- `$res_deg`: Resolution in degrees
- `$crs`: CRS
- The nodata value should **always** be set to 0.

The default Terrain Correction step is:


<node id="Terrain-Correction">
    <operator>Terrain-Correction</operator>
    <sources>
        <sourceProduct refid="LinearToFromdB"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
        <sourceBands/>
        <demName>GETASSE30</demName>
        <externalDEMFile/>
        <externalDEMNoDataValue>0.0</externalDEMNoDataValue>
        <externalDEMApplyEGM>true</externalDEMApplyEGM>
        <demResamplingMethod>BILINEAR_INTERPOLATION</demResamplingMethod>
        <imgResamplingMethod>BILINEAR_INTERPOLATION</imgResamplingMethod>
        <pixelSpacingInMeter>$res_m</pixelSpacingInMeter>
        <pixelSpacingInDegree>$res_deg</pixelSpacingInDegree>
        <mapProjection>$crs</mapProjection>
        <alignToStandardGrid>false</alignToStandardGrid>
        <standardGridOriginX>0.0</standardGridOriginX>
        <standardGridOriginY>0.0</standardGridOriginY>
        <nodataValueAtSea>true</nodataValueAtSea>
        <saveDEM>false</saveDEM>
        <saveLatLon>false</saveLatLon>
        <saveIncidenceAngleFromEllipsoid>false</saveIncidenceAngleFromEllipsoid>
        <saveLocalIncidenceAngle>false</saveLocalIncidenceAngle>
        <saveProjectedLocalIncidenceAngle>false</saveProjectedLocalIncidenceAngle>
        <saveSelectedSourceBand>true</saveSelectedSourceBand>
        <outputComplex>false</outputComplex>
        <applyRadiometricNormalization>false</applyRadiometricNormalization>
        <saveSigmaNought>false</saveSigmaNought>
        <saveGammaNought>false</saveGammaNought>
        <saveBetaNought>false</saveBetaNought>
        <incidenceAngleForSigma0>Use projected local incidence angle from DEM</incidenceAngleForSigma0>
        <incidenceAngleForGamma0>Use projected local incidence angle from DEM</incidenceAngleForGamma0>
        <auxFile>Latest Auxiliary File</auxFile>
        <externalAuxFile/>
    </parameters>
</node>

Default SNAP resolution

You can override default SNAP resolution (in meters) when geocoding SAR bands by setting the following environment variable:

  • EOREADER_SAR_DEFAULT_RES (0.0 by default, which means using the product's default resolution)

Documentary Sources

SAR data

Sentinel-1

Others

Expand source code
"""
SAR products.

.. include:: ../../../documentation/sar_detailed.md
"""

Sub-modules

eoreader.products.sar.csk_product

COSMO-SkyMed products. More info here.

eoreader.products.sar.rs2_product

RADARSAT-2 products. More info here.

eoreader.products.sar.s1_product

Sentinel-1 products

eoreader.products.sar.sar_product

Super class for SAR products

eoreader.products.sar.tsx_product

TerraSAR-X products. More info here.