Loss of resolution in s1 processing

s1tbx
#1

I downloaded Sentinel 1 imagery and processed it with this workflow:

<graph id="Graph">
  <version>1.0</version>
  <node id="Read">
    <operator>Read</operator>
    <sources/>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <file>inputFile</file>
    </parameters>
  </node>
  <node id="Subset">
    <operator>Subset</operator>
    <sources>
      <sourceProduct refid="Read"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <sourceBands>Amplitude_VH,Intensity_VH,Amplitude_VV,Intensity_VV</sourceBands>
      <region>0,0,10710,10004</region>
      <geoRegion>POLYGON</geoRegion>
      <subSamplingX>1</subSamplingX>
      <subSamplingY>1</subSamplingY>
      <fullSwath>false</fullSwath>
      <tiePointGridNames/>
      <copyMetadata>true</copyMetadata>
    </parameters>
  </node>
  <node id="Calibration">
    <operator>Calibration</operator>
    <sources>
      <sourceProduct refid="Subset"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <sourceBands/>
      <auxFile>Product Auxiliary File</auxFile>
      <externalAuxFile/>
      <outputImageInComplex>false</outputImageInComplex>
      <outputImageScaleInDb>false</outputImageScaleInDb>
      <createGammaBand>false</createGammaBand>
      <createBetaBand>false</createBetaBand>
      <selectedPolarisations>VH,VV</selectedPolarisations>
      <outputSigmaBand>true</outputSigmaBand>
      <outputGammaBand>true</outputGammaBand>
      <outputBetaBand>true</outputBetaBand>
    </parameters>
  </node>
  <node id="Speckle-Filter">
    <operator>Speckle-Filter</operator>
    <sources>
      <sourceProduct refid="Calibration"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <sourceBands/>
      <filter>Lee Sigma</filter>
      <filterSizeX>3</filterSizeX>
      <filterSizeY>3</filterSizeY>
      <dampingFactor>2</dampingFactor>
      <estimateENL>true</estimateENL>
      <enl>1.0</enl>
      <numLooksStr>1</numLooksStr>
      <windowSize>7x7</windowSize>
      <targetWindowSizeStr>3x3</targetWindowSizeStr>
      <sigmaStr>0.9</sigmaStr>
      <anSize>50</anSize>
    </parameters>
  </node>
  <node id="Terrain-Correction">
    <operator>Terrain-Correction</operator>
    <sources>
      <sourceProduct refid="SAR-Simulation"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <sourceBands/>
      <demName>SRTM 3Sec</demName>
      <externalDEMFile/>
      <externalDEMNoDataValue>0.0</externalDEMNoDataValue>
      <externalDEMApplyEGM>true</externalDEMApplyEGM>
      <demResamplingMethod>BILINEAR_INTERPOLATION</demResamplingMethod>
      <imgResamplingMethod>BILINEAR_INTERPOLATION</imgResamplingMethod>
      <pixelSpacingInMeter>40.0</pixelSpacingInMeter>
      <pixelSpacingInDegree>3.593261136478086E-4</pixelSpacingInDegree>
      <mapProjection>GEOGCS[&quot;WGS84(DD)&quot;, 
  DATUM[&quot;WGS84&quot;, 
    SPHEROID[&quot;WGS84&quot;, 6378137.0, 298.257223563]], 
  PRIMEM[&quot;Greenwich&quot;, 0.0], 
  UNIT[&quot;degree&quot;, 0.017453292519943295], 
  AXIS[&quot;Geodetic longitude&quot;, EAST], 
  AXIS[&quot;Geodetic latitude&quot;, NORTH]]</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>
  <node id="SAR-Simulation">
    <operator>SAR-Simulation</operator>
    <sources>
      <sourceProduct refid="Speckle-Filter"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <sourceBands/>
      <demName>SRTM 3Sec</demName>
      <demResamplingMethod>BICUBIC_INTERPOLATION</demResamplingMethod>
      <externalDEMFile/>
      <externalDEMNoDataValue>0.0</externalDEMNoDataValue>
      <externalDEMApplyEGM>true</externalDEMApplyEGM>
      <saveLayoverShadowMask>true</saveLayoverShadowMask>
    </parameters>
  </node>
  <node id="BandMaths">
    <operator>BandMaths</operator>
    <sources>
      <sourceProduct refid="Terrain-Correction"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <targetBands>
        <targetBand>
          <name>Sigma0_VH_masked</name>
          <type>float32</type>
          <expression>if layover_shadow_mask_VH &gt; 0 then 0 else Sigma0_VH</expression>
          <description/>
          <unit/>
          <noDataValue>0</noDataValue>
        </targetBand>
      </targetBands>
      <variables/>
    </parameters>
  </node>
  <node id="Write">
    <operator>Write</operator>
    <sources>
      <sourceProduct refid="BandMaths"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <file>outputFile</file>
      <formatName>GeoTIFF</formatName>
    </parameters>
  </node>
  <applicationData id="Presentation">
    <Description/>
    <node id="Read">
            <displayPosition x="37.0" y="134.0"/>
    </node>
    <node id="Subset">
      <displayPosition x="159.0" y="14.0"/>
    </node>
    <node id="Calibration">
      <displayPosition x="206.0" y="164.0"/>
    </node>
    <node id="Speckle-Filter">
      <displayPosition x="149.0" y="229.0"/>
    </node>
    <node id="Terrain-Correction">
      <displayPosition x="370.0" y="318.0"/>
    </node>
    <node id="SAR-Simulation">
      <displayPosition x="179.0" y="280.0"/>
    </node>
    <node id="BandMaths">
      <displayPosition x="487.0" y="240.0"/>
    </node>
    <node id="Write">
            <displayPosition x="455.0" y="135.0"/>
    </node>
  </applicationData>
</graph>

when I compare the result with the data that I can download from the EO-Browser, I see that my resolution is way worse. See the comparison:

06
Bildschirmfoto 2019-11-08 um 22.13.06.png1228×1290 91.5 KB

51
Bildschirmfoto 2019-11-08 um 22.12.51.png1234×1296 402 KB

What am I doing wrong?

Thanks!

#2

I think the first thing is the DEM you selected in SAR simulation, select 1 sec SRTM, yes the resolution is taken from the source SAR image, but might it affects.

Also make the TC the last step not before SAR simulation.

Apply orbit should be the fist operator.

I think the graph should be recreated the steps.

image
image.png773×335 12.8 KB

#4

the terrain correction pixel spacing is set to 40m

<pixelSpacingInMeter>40.0</pixelSpacingInMeter>

also try it without the speckle filter