Graphic symbology in GeoServer¶

Standard symbols¶

The SLD specification mandates the support of the following symbols:

Shape symbols¶

The shape symbols set adds extra symbols that are not part of the basic set.

1. To enable ensure that the WMS Settings :guilabel:Mark Factory Precedence has ShapeMarkFactory selected.

2. The shape symbols are prefixed by shape://

   Name	Description
   shape://vertline	A vertical line (suitable for hatch fills or to make railroad symbols)
   shape://horline	A horizontal line (suitable for hatch fills)
   shape://slash	A diagonal line leaning forwards like the “slash” keyboard symbol (suitable for diagonal hatches)
   shape://backslash	Same as shape://slash, but oriented in the opposite direction
   shape://dot	A very small circle with space around
   shape://plus	A + symbol, without space around (suitable for cross-hatch fills)
   shape://times	A “X” symbol, without space around (suitable for cross-hatch fills)
   shape://oarrow	An open arrow symbol (triangle without one side, suitable for placing arrows at the end of lines)
   shape://carrow	A closed arrow symbol (closed triangle, suitable for placing arrows at the end of lines)

Weather Symbols¶

The weather symbols are prefixed by the extshape:// protocol in the SLD:

1. To enable ensure that the WMS Settings :guilabel:Mark Factory Precedence has MeteoMarkFactory selected.

2. These symbols are:

   Name	Description	Produces
   extshape://triangle	cold front
   extshape://emicircle	warm front
   extshape://triangleemicircle	stationary front

3. You can use extshape:// for a few additional built-in shapes:

   extshape://narrow	North Arrow
   extshape://sarrow	South Arrow

More complex symbols like Wind Barbs can be created with the windbarbs:// prefix.

1. To enable ensure that the WMS Settings :guilabel:Mark Factory Precedence has WindBarbsmFactory selected.

2. There are some examples:

   Name	Description
   windbarbs://default(15)[kts]	15 wind intensity with [kts] unit of measure
   windbarbs://default(9)[m/s]?hemisphere=s	9 wind intensity with [m/s] unit of measure, in the south hemisphere

Custom WKT Shapes¶

Custom shapes can be defined using your own Geometry, to enable use WMS Settings :guilabel:Mark Factory Precedence to select WKTMarkFactory.

Geometry is defined using the same well-known-text format used for CQL_FILTER.

<LineSymbolizer>
  <Stroke>
    <GraphicStroke>
      <Graphic>
        <Mark>
          <WellKnownName>wkt://MULTILINESTRING((-0.25 -0.25, -0.125 -0.25), (0.125 -0.25, 0.25 -0.25), (-0.25 0.25, -0.125 0.25), (0.125 0.25, 0.25 0.25))</WellKnownName>
          <Fill>
            <CssParameter name="fill">#0000ff</CssParameter>
          </Fill>
          <Stroke>
            <CssParameter name="stroke">#0000ff</CssParameter>
            <CssParameter name="stroke-width">1</CssParameter>
          </Stroke>
        </Mark>
        <Size>6</Size>
      </Graphic>
    </GraphicStroke>
  </Stroke>
</LineSymbolizer>

Which produces double dashed line:

You can also make use of curves when defining WKT:

<LineSymbolizer>
  <Stroke>
    <GraphicStroke>
      <Graphic>
        <Mark>
          <WellKnownName>wkt://COMPOUNDCURVE((0 0, 0.25 0), CIRCULARSTRING(0.25 0, 0.5 0.5, 0.75 0), (0.75 0, 1 0))</WellKnownName>
          <Fill>
            <CssParameter name="fill">#0000ff</CssParameter>
          </Fill>
          <Stroke>
            <CssParameter name="stroke">#0000ff</CssParameter>
            <CssParameter name="stroke-width">1</CssParameter>
          </Stroke>
        </Mark>
        <Size>10</Size>
      </Graphic>
    </GraphicStroke>
  </Stroke>
</LineSymbolizer>

Producing an “emi circle” line:

Bulk TTF marks¶

It is possible to create a mark using glyphs from any decorative or symbolic True Type Font, such as Wingdings, WebDings, or the many symbol fonts available on the internet. To enable use WMS Settings :guilabel:Mark Factory Precedence to select TTFMarkFactory.

The syntax for specifying this is:

ttf://<fontname>#<hexcode>

where fontname is the full name of a TTF font available to GeoServer, and hexcode is the hexadecimal code of the symbol. To get the hex code of a symbol, use the “Char Map” utility available in most operating systems (Windows and Linux Gnome both have one).

For example, to use the “shield” symbol contained in the WebDings font, the Gnome charmap reports the symbol hex code as shown:

The SLD to use the shield glyph as a symbol is:

 1 <PointSymbolizer>
 2     <Graphic>
 3       <Mark>
 4         <WellKnownName>ttf://Webdings#0x0064</WellKnownName>
 5         <Fill>
 6           <CssParameter name="fill">#AAAAAA</CssParameter>
 7         </Fill>
 8         <Stroke/>
 9       </Mark>
10     <Size>16</Size>
11   </Graphic>
12 </PointSymbolizer>

This results in the following map display:

Extending the Mark subsystem using Java¶

The Mark subsystem is user-extensible. To do this using Java code, implement the MarkFactory interface and declare the implementation in the META-INF/services/org.geotools.renderer.style.MarkFactory file.

For further information see the Javadoc of the GeoTools MarkFactory, along with the following example code:

• The factory SPI registration file

• The TTFMarkFactory implementation

• The ShapeMarkFactory implementation

SVG Parameters¶

GeoServer can handle SVG images in which parts of the SVG-attributes are named parameters, as outlined the SVG Parameters 1.0 specification. This capability is also supported by QGIS.

SVG Parameters are represented in a file like: poi_peak.svg as:

<svg enable-background="new 0 0 580 580" height="580" viewBox="0 0 580 580" width="580" xmlns="http://www.w3.org/2000/svg">
<path d="m290.565 67.281l-255.498 442.534-1.087 1.885 511.229.393 2.18.002z" fill="param(fill)"
 fill-opacity="param(fill-opacity)" stroke="param(outline)" stroke-opacity="param(outline-opacity)" stroke-width="param(outline-width)"/>
</svg>

The ‘param’-constructs mean that you can define the parameters: fill, fill-opacity, outline, outline-opacity and outline-width as part of an SVG URL reference, where a reference to this image with red fill would be: poi_peak.svg?fill=#FF0000.

Note: When editng SVG files (e.g. in Inkscape) save using ‘simple svg’ format.

Default behaviour:

• OnlineResource href URI without any parameters.

  <se:OnlineResource xlink:href="poi_peak.svg" xlink:type="simple"/>
  

• Displays poi_peak.svg with the default black fill.

  

Using #ff000 red parameter:

• OnlineResource href URI with parameter:

  <se:OnlineResource xlink:href="poi_peak.svg?fill=#ff0000" xlink:type="simple"/>
  

• Displays poi_peak.svg with supplied red fill.

  

To define several parameters, the query-parameters should be url-encoded.

• A green peak with 25% opacity: ?fill=#00ff00&opacity=0.25, requires encoding both the ‘#’ ( %23 ) and the ‘&’ ( & ) signs:

  <se:OnlineResource xlink:href="poi_peak.svg?fill=%2300ff00&amp;opacity=0.25" xlink:type="simple"/>
  

• Displayed with white fill, red outlined peaks:

  

Parameters names are defined by the SVG file:

• The parameter ‘stroke’ above is called ‘outline’ in the original svg file:

  stroke="param(outline)"
  

• OnlineResource href URI referencing parameters fill, outline and outline-width:

  <se:OnlineResource xlink:href="poi_peak.svg?fill=%23ffffff&amp;outline=%23ff0000&amp;outline-width=5" xlink:type="simple"/>
  

• Displayed as:

  

The use of SVG parameters can be combinded with dynamic symbolizers (covered below) to supply SVG parameter values based on feature attribute data and expressions.

• OnlineResource href URI referencing SVG Parameter with dynamic CQL expression:

  <se:OnlineResource xlink:href="poi_peak.svg?fill=${COLOR}" xlink:type="simple"/>
  

• Display depends on the feature attribute COLOR.

Bulk WKT Shapes¶

It is possible to create a symbol set of your own custom marks using a property file.

Here is an example.properties:

zig=LINESTRING(0.0 0.25, 0.25 0.25, 0.5 0.75, 0.75 0.25, 1.00 0.25)
block=POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))

The SLD to use the symbols defined in example.properties is:

 1 <PointSymbolizer>
 2   <Graphic>
 3     <ExternalGraphic>
 4       <OnlineResource
 5         xlink:type="simple"
 6         xlink:href="example.properties#zig" />
 7       <Format>wkt</Format>
 8     </ExternalGraphic>
 9     <Size>20</Size>
10   </Graphic>
11 </PointSymbolizer>

Symbol Positioning¶

Graphic symbols are rendered so that the center of the graphic extent lies on the placement point (or points, in the case of repeated or tiled graphics). If it is desired to have a graphic offset from a point (such as a symbol which acts as a pointer) it is necessary to offset the visible portion of the graphic within the overall extent. For images this can be accomplished by extending the image with transparent pixels. For SVG graphics this can be done by surrounding the shape with an invisible rectangle with the desired relative position.