Contours

The following example XML file shows a reanalysis of sea surface temperature as a colour map, with the analysis error as contours.

<?xml version="1.0" encoding="ISO-8859-1"?>
<StyledLayerDescriptor version="1.1.0" xsi:schemaLocation="http://www.opengis.net/sld
StyledLayerDescriptor.xsd" xmlns="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:se="http://www.opengis.net/se" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:resc="http://www.resc.reading.ac.uk">
  <NamedLayer>
    <se:Name>OSTIA/analysed_sst</se:Name>
    <UserStyle>
      <se:Name>Red-blue palette showing SST</se:Name>
      <se:CoverageStyle>
        <se:Rule>
          <se:RasterSymbolizer>
            <se:Opacity>1.0</se:Opacity>
            <se:ColorMap>
              <resc:Segment fallbackValue="#FF006400">
                <se:LookupValue>Rasterdata</se:LookupValue>
                <resc:BelowMinValue>extend</resc:BelowMinValue>
                <resc:ValueList>
                  <se:Name>div-BuRd2</se:Name>
                </resc:ValueList>
                <resc:AboveMaxValue>extend</resc:AboveMaxValue>
                <resc:Range>
                  <resc:Minimum>270.0</resc:Minimum>
                  <resc:Maximum>310.0</resc:Maximum>
                  <resc:Spacing>linear</resc:Spacing>
                </resc:Range>
                <resc:NumberOfSegments>250</resc:NumberOfSegments>
              </resc:Segment>
            </se:ColorMap>
          </se:RasterSymbolizer>
        </se:Rule>
      </se:CoverageStyle>
    </UserStyle>
  </NamedLayer>
  <NamedLayer>
    <se:Name>OSTIA/analysis_error</se:Name>
    <UserStyle>
      <se:Name>Contours showing error</se:Name>
      <se:CoverageStyle>
        <se:Rule>
          <resc:ContourSymbolizer>
            <se:Opacity>1.0</se:Opacity>
            <resc:NumberOfContours>10</resc:NumberOfContours>
            <resc:ContourLineColour>black</resc:ContourLineColour>
            <resc:ContourLineStyle>SOLID</resc:ContourLineStyle>
            <resc:ContourLineWidth>1</resc:ContourLineWidth>
            <resc:Range>
              <resc:Minimum>0</resc:Minimum>
              <resc:Maximum>2.5</resc:Maximum>
              <resc:Spacing>linear</resc:Spacing>
            </resc:Range>
          </resc:ContourSymbolizer>
        </se:Rule>
      </se:CoverageStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

The resulting output image and its legend are shown below: