MapServer Symbology – How to Style MapServer Layers Easily

mapfilemapserversldstylesymbology

I am working with MapServer WMS in the form of mapfiles and consuming them into a OpenLayers map.

I am trying to find out a way to ease the symbolization process of the various layers in a mapfile.

I have not started diving into the STYLE directive yet, but before I do that I'd like to know whether there's an easy way to (let's say) preview the style of my layers (an application?) and export it into a (e.g.) SLD which the MapServer can read.

I don't know if this is the best (or feasible) way to go about styling mapfile's layers, but I am open to any kind of suggestion.

Best Answer

You can't use SLD to internally style a MapServer WMS map, you'll have to use the STYLE directives.

However

MapServer will take an SLD as part of a GetMap request, either by reference (you link to a URL of the SLD), using the SLD=[your link to your SLD]& parameter or directly as part of the SLD_BODY=[your SLD]& parameter.

You can review this in a browser.

Exercise

Consider a MapServer WMS providing radon information.

A GetMap request using the default style might look like:

http://ogc.bgs.ac.uk/cgi-bin/BGS_BGS-HPA_Radon_Potential/wms?language=eng&VERSION=1.3.0&REQUEST=GetMap&CRS=EPSG:4326&BBOX=50.179445759563,-4.41340973640857,50.9615344710795,-3.2834397199341&WIDTH=877&HEIGHT=607&LAYERS=GBR_BGS-HPA_625K_RADON_POTENTIAL&STYLES=&EXCEPTIONS=XML&FORMAT=image/png&BGCOLOR=0xFEFFFF&TRANSPARENT=TRUE&

Giving a map like:

The map file definition of the style is:

    CLASS
        # Dummy for legend title
        MINSCALEDENOM 250000
        NAME "Bq m3"
        EXPRESSION ""
        STYLE
            COLOR 255 255 255
        END
    END
    CLASS
        MINSCALEDENOM 250000
        NAME "> 499.99"
        EXPRESSION ">499.99"
        STYLE
            COLOR 255 0 0
        END
    END
    CLASS
        MINSCALEDENOM 250000
        NAME "200 - 499.99"
        EXPRESSION "200 - 499.99"
        STYLE
            COLOR 230 152 0
        END
    END
    CLASS
        MINSCALEDENOM 250000
        NAME "100 - 199.99"
        EXPRESSION "100 - 199.99"
        STYLE
            COLOR 255 255 0
        END
    END
    CLASS
        MINSCALEDENOM 250000
        NAME "50 - 99.99"
        # EXPRESSION "50 - 99.99"
        EXPRESSION "[50 - 99.99]"
        STYLE
            COLOR 190 210 255
        END
    END
    CLASS
        MINSCALEDENOM 250000
        NAME "20 - 49.99"
        EXPRESSION "20 - 49.99"
        STYLE
            COLOR 0 112 255
        END
    END
    CLASS
        MINSCALEDENOM 250000
        NAME "< 20"
        EXPRESSION "< 20"
        STYLE
            COLOR 0 77 168
        END
    END

But a general user can't see this. A user though can make a GetStyles request like:

http://ogc.bgs.ac.uk/cgi-bin/BGS_BGS-HPA_Radon_Potential/wms?version=1.3.0&service=WMS&request=GetStyles&sld_version=1.1.0&layers=GBR_BGS-HPA_625K_RADON_POTENTIAL&STYLE=default&

Which is MapServers effort at converting the internal style to SLD, so here it gives us:

<?xml version="1.0" encoding="UTF-8"?>
<StyledLayerDescriptor version="1.1.0" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/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">
    <NamedLayer>
        <se:Name>GBR_BGS-HPA_625K_RADON_POTENTIAL</se:Name>
        <UserStyle>
            <se:FeatureTypeStyle>
                <se:Rule>
                    <se:Name>Bq m3</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal></ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#ffffff</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
                <se:Rule>
                    <se:Name>&gt; 499.99</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal>>499.99</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#ff0000</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
                <se:Rule>
                    <se:Name>200 - 499.99</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal>200 - 499.99</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#e69800</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
                <se:Rule>
                    <se:Name>100 - 199.99</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal>100 - 199.99</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#ffff00</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
                <se:Rule>
                    <se:Name>50 - 99.99</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal>50 - 99.99</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#bed2ff</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
                <se:Rule>
                    <se:Name>20 - 49.99</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal>20 - 49.99</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#0070ff</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
                <se:Rule>
                    <se:Name>&lt; 20</se:Name>
                    <ogc:Filter><ogc:PropertyIsEqualTo><ogc:PropertyName>AM_GFRn</ogc:PropertyName><ogc:Literal>&lt; 20</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Filter>
                    <se:MinScaleDenominator>250000.000000</se:MinScaleDenominator>
                    <se:PolygonSymbolizer>
                        <se:Fill>
                            <se:SvgParameter name="fill">#004da8</se:SvgParameter>
                        </se:Fill>
                    </se:PolygonSymbolizer>
                </se:Rule>
            </se:FeatureTypeStyle>
        </UserStyle>
    </NamedLayer>
</StyledLayerDescriptor>

We could take this style, modify it, put it on a server, and request it as part of a GetMap request like:

http://ogc.bgs.ac.uk/cgi-bin/BGS_BGS-HPA_Radon_Potential/wms?language=eng&VERSION=1.3.0&REQUEST=GetMap&CRS=EPSG:4326&BBOX=50.179445759563,-4.41340973640857,50.9615344710795,-3.2834397199341&WIDTH=877&HEIGHT=607&LAYERS=GBR_BGS-HPA_625K_RADON_POTENTIAL&STYLES=&EXCEPTIONS=XML&FORMAT=image/png&BGCOLOR=0xFEFFFF&TRANSPARENT=TRUE&sld=http://ogc.bgs.ac.uk/sld/radon1.sld&

Giving us:

Related Solutions

[GIS] How to apply a raster style to multiple layers using MapServer

Not yet.. Here's what we're left with...eg: the copy and paste method. Example:

LAYER                                                   #-> BEGIN LAYER DEFINITION: Land Cover <-#
    NAME    landcover                                   # Layer identifier
    DATA    "data/wgs84/landcover_360.tif"              # Name of the data (in this case, string identifying a raster)
    STATUS  DEFAULT                                     # Default (always on) <-OR-> ON/OFF (passed into query string)
    TYPE    RASTER                                      # Data type (point, line, polygon or raster)
    OPACITY 100                                         # Layer transparency (0-100 <-OR-> ALPHA)
    OFFSITE 0 0 0                                       # Image background colour

    CLASS                                               #-> BEGIN CLASS
        NAME    "Land Cover: Urban"                     # Name of class (used in legend)
        EXPRESSION ([pixel] = 2)                        # Attribute query

        STYLE                                           #-> BEGIN STYLE
            OPACITY 100                                 # Transparency
            COLOR 0 0 0                                 # Fill colour
        END                                             #-> END STYLE
    END                                                 #-> END CLASS

    CLASS                                               #-> BEGIN CLASS
        NAME    "Land Cover: Agriculture"               # Name of class (used in legend)
        EXPRESSION ([pixel] = 1)                        # Attribute query

        STYLE                                           #-> BEGIN STYLE
            OPACITY 80                                  # Transparency
            COLOR 0 0 0                                 # Fill colour
        END                                             #-> END STYLE
    END                                                 #-> END CLASS
END                                                     #-> END LAYER DEFINITION: Land Cover <-#

LAYER                                                   #-> BEGIN LAYER DEFINITION: Roads <-#
    NAME    roads                                       # Layer identifier
    DATA    "data/wgs84/roads_360.tif"                  # Name of the data (in this case, string identifying a raster)
    STATUS  DEFAULT                                     # Default (always on) <-OR-> ON/OFF (passed into query string)
    TYPE    RASTER                                      # Data type (point, line, polygon or raster)
    OPACITY 100                                         # Layer transparency (0-100 <-OR-> ALPHA)
    OFFSITE 0 0 0                                       # Image background colour

    CLASS                                               #-> BEGIN CLASS
        NAME    "Roads: Within 2km"                     # Name of class (used in legend)
        EXPRESSION ([pixel] = 2)                        # Attribute query

        STYLE                                           #-> BEGIN STYLE
            OPACITY 100                                 # Transparency
            COLOR 0 0 0                                 # Fill colour
        END                                             #-> END STYLE
    END                                                 #-> END CLASS

    CLASS                                               #-> BEGIN CLASS
        NAME    "Roads: Between 2 and 15km"             # Name of class (used in legend)
        EXPRESSION ([pixel] = 1)                        # Attribute query

        STYLE                                           #-> BEGIN STYLE
            OPACITY 50                                  # Transparency
            COLOR 0 0 0                                 # Fill colour
        END                                             #-> END STYLE
    END                                                 #-> END CLASS
END                                                     #-> END LAYER DEFINITION: Roads <-#

Style holds parameters for symbolization and styling. Multiple styles may be applied within a CLASS or LABEL.

This object appeared in 4.0 and the intention is to separate logic from looks. The final intent is to have named styles (Not yet supported) that will be re-usable through the mapfile. This is the way of defining the appearance of an object (a CLASS or a LABEL).

[GIS] Rotating PIXMAP based symbols correctly in MapServer

I have tested on 5.0.3 (could not find 5.0.4, so it might have been a developing version). The following mapfile works for me (line50.map):

MAP
  SIZE 300 75
  IMAGETYPE png24
  EXTENT 0 40 60 55
  UNITS meters

  SYMBOL
    NAME "o-flag-gap"
    TYPE pixmap
    IMAGE "o-flag.png"
    GAP 30
  END # SYMBOL

  LAYER  # Line - pixmap overlay
    STATUS DEFAULT
    TYPE LINE
    FEATURE
      POINTS
        5 45
        25 50
        55 45
      END # Points
    END # Feature
    CLASS
      STYLE
        COLOR 0 0 0
        SIZE 6
      END # STYLE
      STYLE
        COLOR 102 0 0
        SYMBOL "o-flag-gap"
        SIZE 20
      END # STYLE
    END # CLASS
  END # LAYER
END # MAP

Run:

shp2img -m line50.map -o line50.png

The result is:

mapserver output

I have been using a basic 5.0.3 configuration:

$ mapserv -v
MapServer version 5.0.3 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP OUTPUT=PDF OUTPUT=SVG SUPPORTS=FREETYPE INPUT=EPPL7 INPUT=JPEG INPUT=SHAPEFILE

The sign of GAP does not seem to have an any effect - the symbol is always oriented according to the direction of the line.

Best Answer

Related Solutions

[GIS] How to apply a raster style to multiple layers using MapServer

[GIS] Rotating PIXMAP based symbols correctly in MapServer

Related Question