SAR data¶

You will find a SAR tutorial here.

Implemented SAR satellites¶

Satellites	Class	Use archive
`COSMO-Skymed 1st Generation`	`CskProduct`	❌
`COSMO-Skymed 2nd Generation`	`CsgProduct`	❌
`ICEYE`	`IceyeProduct`	❌
`RADARSAT Constellation Mission`	`RcmProduct`	❌
`RADARSAT-2`	`Rs2Product`	✅ for ground range data, ❌ for complex data
`Sentinel-1`	`S1Product`	✅
`SAOCOM-1`	`SaocomProduct`	❌
`TerraSAR-X`, `TanDEM-X`, `PAZ SAR`	`TsxProduct`	❌

Warning

Satellites products that cannot be used as archived have to be extracted before use, mostly because SNAP doesn’t handle them.

Product type handling¶

Sensor	Product Type	Handled
`COSMO-Skymed`	SCS	✅
`COSMO-SkyMed` 1st Generation	DGM	✅
`COSMO-SkyMed` 2nd Generation	DGM	⚠️
`COSMO-SkyMed`	GEC, GTC	⚠️
`ICEYE`	SLC	❌*
`ICEYE`	GRD	✅
`ICEYE`	ORTHO	💤
`RADARSAT Constellation Mission`	SLC	⚠️
`RADARSAT Constellation Mission`	GRC, GCC, GCD	⚠️
`RADARSAT Constellation Mission`	GRD	✅
`RADARSAT-2`	SLC	✅
`RADARSAT-2`	SGX, SCN, SCW, SCF, SCS, SSG, SPG	⚠️
`RADARSAT-2`	SGF	✅
`Sentinel-1`	SLC	✅
`Sentinel-1`	GRD	✅
`SAOCOM-1`	SLC	✅
`SAOCOM-1`	ID	⚠
`SAOCOM-1`	GEC	✅
`SAOCOM-1`	GTC	✅
`TerraSAR-X`, `TanDEM-X`, `PAZ SAR`	SSC	✅
`TerraSAR-X`, `TanDEM-X`, `PAZ SAR`	MGD	✅
`TerraSAR-X`, `TanDEM-X`, `PAZ SAR`	GEC	⚠️
`TerraSAR-X`, `TanDEM-X`, `PAZ SAR`	EEC	✅

*always given with a GRD image

✅: Tested
⚠️: Never tested, use it at your own risk!
❌: Not handled
💤: Waiting for the release

The goal of EOReader is to implement every sensor that can be used in the Copernicus Emergency Management Service. The sensors that can be used during CEMS activations are (as of 09/2021):
cems_sensors

SAR Bands¶

Warning

EOReader always loads SAR bands in a GRD format. This library is not (yet ?) meant to manage inSAR or other complex processes.
Only the Intensity bands are used (not the I, Q for complex data or Amplitude for ground range data)
Some SAR band may contain null pixels that are not really nodata (COSMO for example).
In this case, the Terrain Correction step applied by SNAP can create large nodata area.
If this is the case, you can set the keyword SAR_INTERP_NA to True when loading or stacking SAR data

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

VV
VH
HH
HV
RH (only for RADARSAT-Constellation)
RV (only for RADARSAT-Constellation)

You also can load despeckled bands:

VV_DSPK
VH_DSPK
HH_DSPK
HV_DSPK
RH_DSPK (only for RADARSAT-Constellation)
RV_DSPK (only for RADARSAT-Constellation)

DEM bands¶

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

DEM
SLOPE

SAR satellites can only load DEM and SLOPE bands as the sun position does not impact SAR data. The SLOPE band is given in degrees. Please post an issue if you need this band in percent.

These bands need a valid worldwide DEM path positioned thanks to the environment variable EOREADER_DEM_PATH. You can use both a local path e.g. /mnt/dataserver/dems/srtm_30_v4/index.vrt or \\dataserver\DEMS\srtm_30_v4\index.vrt or a URL pointing to a web resources hosted on a S3 compatible storage e.g. https://s3.storage.com/dem-bucket/srtm_cog.tif (not available on Windows for now).

Default resolution¶

The default resolution of SAR products depends on their type. Complex data are always converted back to ground range to be used, so the complex resolution is never used by EOReader.

The product resolution is read in the metadata file if possible, except for complex data. For them, Grand Range values from the constructor are used.

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 1st Generation¶

COSMO-Skymed 1st Generation	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

COSMO-Skymed 2nd Generation¶

Only for Standard products

COSMO-Skymed 2nd Generation	Single-look Complex Slant (SCS)	Detected Ground Multi-look (DGM)Geocoded Ellipsoid Corrected (GEC) Geocoded Terrain Corrected (GTC)
SPOTLIGHT_2_A	~0.25m	#1: 0.15m (apodized: 0.12m) #2: 0.30m #3: 0.45m
SPOTLIGHT_2_B	~0.45m	#1: 0.25m (apodized: 0.2m) #2: 0.50m #3: 1.0m
SPOTLIGHT-2C	~0.56m	#1: 0.30m (apodized: 0.24m) #2: 0.60m #3: 0.9m
STRIPMAP & QUADPOL	≤ 3.0m	#1: 1.25m #2: 2.5m #3: 5.0m
SCANSAR1	14.0m	#1: 5.0m #2: 10.0m #3: 15.0m
SCANSAR2	27.0m	#1: 10.0m #2: 20.0m #3: 50.0m
PINGPONG	8.0m	#1: 2.0m #2: 4.0m #3: 10.0m

#1, #2 and #3 correspond to the MultiLook ID.

TerraSAR-X & TanDEM-X & PAZ SAR¶

TerraSAR-X & TanDEM-X & PAZ SAR	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

RADARSAT-Constellation¶

RADARSAT-Constellation	Resolution*
Spotlight [FSL]	≈ 1.0 x 3.0m à 35°
Very-High Resolution, 3 meters [3M]	≈ 3.0 x 3.0m à 35°
High Resolution, 5 meters [5M]	≈ 5.0 x 5.0m
Quad-Polarization [QP]	≈ 9.0 x 9.0m
Medium Resolution, 16 meters [16M]	≈ 16.0 x 16.0m
Medium Resolution, 30 meters [SC30]	≈ 30.0 x 30.0m
Medium Resolution, 50 meters [SC50]	≈ 50.0 x 50.0m
Low Noise [SCLN]	≈ 100.0 x 100.0m
Low Resolution, 100 meters [SC100]	≈ 100.0 x 100.0m
Ship Detection	Variable

* Same resolution for every product type according to that page.

ICEYE¶

For GRD products:

ICEYE	Ground sample spacing (pixel size)
Spotlight [SL(H)]	0.5m
StripMap [SM(H)]	2.5m
Scan [SC]	6.0m

ICEYE	Resolution
Spotlight [SL(H)]	1.0m
StripMap [SM(H)]	3.0m
Scan [SC]	< 15.0m

SAOCOM-1¶

SAOCOM-1	Single-Look Complex (SLC)	Detected Image (DI) Geocoded Ellipsoid Corrected (GEC) Geocoded Terrain Corrected (GTC)
StripMap (SM) Single and Dual Pol	10x5m	10.0m
StripMap (SM) Quad Pol	10x6m	10.0m
TOPSAR Narrow (TN) Single and Dual Pol	10x30m	30.0m
TOPSAR Narrow (TN) Quad Pol	10x50m	50.0m
TOPSAR Wide (TW) Single and Dual Pol	10x50m	50.0m
TOPSAR Wide (TW) Quad Pol	10x100m	100.0m

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.

You can change the DEM used for the Terrain Correction step by positioning the EOREADER_SNAP_DEM_NAME environment variable. Available DEMs are:

ACE2_5Min
ACE30
ASTER 1sec GDEM
Copernicus 30m Global DEM (buggy for now, do not use it)
Copernicus 90m Global DEM (buggy for now, do not use it)
GETASSE30 (by default)
SRTM 1Sec HGT
SRTM 3Sec
External DEM

If External DEM is set, you must specify the DEM you want by positioning the EOREADER_DEM_PATH to a DEM that can be read by SNAP.

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.

SNAP graphs are run on every band separatly.

The pre-processing graph should also have a Calibration and a Terrain Correction step with the following wildcards that are set automatically in the module:

$calib_pola: Polarization of the band to calibrate
$dem_name: SNAP DEM name
$dem_path: DEM path (that can be use by SNAP, so only TIFF DEMs)
$res_m: Resolution in meters
$res_deg: Resolution in degrees
$crs: CRS
The nodata value should always be set to 0.

The default Calibration step is:

<node id="Calibration">
    <operator>Calibration</operator>
    <sources>
        <sourceProduct refid="ThermalNoiseRemoval"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
        <sourceBands/>
        <auxFile>Latest Auxiliary File</auxFile>
        <externalAuxFile/>
        <outputImageInComplex>false</outputImageInComplex>
        <outputImageScaleInDb>false</outputImageScaleInDb>
        <createGammaBand>false</createGammaBand>
        <createBetaBand>false</createBetaBand>
        <selectedPolarisations>${calib_pola}</selectedPolarisations>
        <outputSigmaBand>true</outputSigmaBand>
        <outputGammaBand>false</outputGammaBand>
        <outputBetaBand>false</outputBetaBand>
    </parameters>
</node>

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>${dem_name}</demName>
        <externalDEMFile>${dem_path}</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

SAR data

Contents

SAR data¶

Implemented SAR satellites¶

Product type handling¶

SAR Bands¶

DEM bands¶

Default resolution¶

Sentinel-1¶

COSMO-Skymed 1st Generation¶

COSMO-Skymed 2nd Generation¶

TerraSAR-X & TanDEM-X & PAZ SAR¶

RADARSAT-2¶

RADARSAT-Constellation¶

ICEYE¶

SAOCOM-1¶

GPT graphs¶

What to know if you are changing a graph¶

Default SNAP resolution¶

Documentary Sources¶

Copernicus¶

Sentinel-1¶

RADARSAT¶

COSMO-Skymed¶

TerraSAR-X, TanDEM-X and PAZ SAR¶

ICEYE¶

SAOCOM-1¶