GeoServer rendering transformation

raster-to-vector.sld.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<StyledLayerDescriptor version="1.0.0" xsi:schemaLocation="http://www.opengis.net/sld StyledLayerDescriptor.xsd"
    xmlns="http://www.opengis.net/sld"
    xmlns:ogc="http://www.opengis.net/ogc"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <NamedLayer>
        <Name></Name>
        <UserStyle>
            <Title>Contour DEM</Title>
            <Abstract>Extracts contours from DEM</Abstract>
            <FeatureTypeStyle>
                <Rule>
                  <Name>color</Name>
                  <Title>color</Title>
                  <RasterSymbolizer>
                     <ColorMap>
                       <ColorMapEntry color="#5b9dd3" quantity="-40" />
                       <ColorMapEntry color="#5792c2" quantity="-30" />
                       <ColorMapEntry color="#5595bb" quantity="-20" />
                       <ColorMapEntry color="#5097b3" quantity="-20" />
                       <ColorMapEntry color="#57a8ab" quantity="-10" />
                       <ColorMapEntry color="#6b7e82" quantity="0" />
                       <ColorMapEntry color="#afa906" quantity="10" />
                       <ColorMapEntry color="#08c601" quantity="20" />
                       <ColorMapEntry color="#08c601" quantity="30" />
                       <ColorMapEntry color="#08c601" quantity="40" />
                       <ColorMapEntry color="#08c601" quantity="50" />
                       <ColorMapEntry color="#08c601" quantity="60" />
                    </ColorMap>
                 </RasterSymbolizer>
                </Rule>
            </FeatureTypeStyle>
            <FeatureTypeStyle>
                <Transformation>
                    <ogc:Function name="ras:Contour">
                        <ogc:Function name="parameter">
                            <ogc:Literal>data</ogc:Literal>
                        </ogc:Function>
                        <ogc:Function name="parameter">
                            <ogc:Literal>levels</ogc:Literal>
                            <ogc:Literal>-40</ogc:Literal>
                            <ogc:Literal>-30</ogc:Literal>
                            <ogc:Literal>-20</ogc:Literal>
                            <ogc:Literal>-10</ogc:Literal>
                            <ogc:Literal>0</ogc:Literal>
                            <ogc:Literal>10</ogc:Literal>
                            <ogc:Literal>20</ogc:Literal>
                            <ogc:Literal>30</ogc:Literal>
                            <ogc:Literal>40</ogc:Literal>
                            <ogc:Literal>50</ogc:Literal>
                            <ogc:Literal>60</ogc:Literal>
                        </ogc:Function>
                    </ogc:Function>
                </Transformation>
                <Rule>
                    <Name>contour</Name>
                    <Title>Contour Line</Title>
                    <LineSymbolizer>
                        <Stroke>
                            <CssParameter name="stroke">#000000</CssParameter>
                            <CssParameter name="stroke-width">1</CssParameter>
                        </Stroke>
                    </LineSymbolizer>
                    <TextSymbolizer>
                        <Label>
                            <ogc:PropertyName>value</ogc:PropertyName>
                        </Label>
                        <Font>
                            <CssParameter name="font-family">Arial</CssParameter>
                            <CssParameter name="font-style">Normal</CssParameter>
                            <CssParameter name="font-size">10</CssParameter>
                        </Font>
                        <LabelPlacement>
                            <LinePlacement/>
                        </LabelPlacement>
                        <Halo>
                            <Radius>
                                <ogc:Literal>2</ogc:Literal>
                            </Radius>
                            <Fill>
                                <CssParameter name="fill">#FFFFFF</CssParameter>
                                <CssParameter name="fill-opacity">0.6</CssParameter>
                            </Fill>
                        </Halo>
                        <Fill>
                            <CssParameter name="fill">#000000</CssParameter>
                        </Fill>
                        <Priority>2000</Priority>
                        <VendorOption name="followLine">true</VendorOption>
                        <VendorOption name="repeat">100</VendorOption>
                        <VendorOption name="maxDisplacement">50</VendorOption>
                        <VendorOption name="maxAngleDelta">30</VendorOption>
                    </TextSymbolizer>
                </Rule>
            </FeatureTypeStyle>
        </UserStyle>
    </NamedLayer>
</StyledLayerDescriptor>