PointSymbolizer

The PointSymbolizer styles points, Points are elements that contain only position information.

Syntax

The outermost element is the <Graphic> tag. This determines the type of visualization. There are five possible tags to include inside the <Graphic> tag:

Tag Required? Description
<ExternalGraphic> No (when using <Mark>) Specifies an image file to use as the symbolizer.
<Mark> No (when using <ExternalGraphic>) Specifies a common shape to use as the symbolizer.
<Opacity> No Determines the opacity (transparency) of symbolizers. Values range from 0 (completely transparent) to 1 (completely opaque). Default is 1.
<Size> Yes Determines the size of the symbolizer in pixels. When used with an image file, this will specify the height of the image, with the width scaled accordingly.
<Rotation> No Determines the rotation of the graphic in degrees. The rotation increases in the clockwise direction. Negative values indicate counter-clockwise rotation. Default is 0.

Within the <ExternalGraphic> tag, there are also additional tags:

Tag Required? Description
<OnlineResource> Yes The location of the image file. Can be either a URL or a local path relative to the SLD.
<Format> Yes The MIME type of the image format. Most standard web image formats are supported.

Within the <Mark> tag, there are also additional tags:

Tag Required? Description
<WellKnownName> Yes The name of the common shape. Options are circle, square, triangle, star, cross, or x. Default is square.
<Fill> No (when using <Stroke>) Specifies how the symbolizer should be filled. Options are a <CssParameter name="fill"> specifying a color in the form #RRGGBB, or <GraphicFill> for a repeated graphic.
<Stroke> No (when using <Fill>) Specifies how the symbolizer should be drawn on its border. Options are a <CssParameter name="fill"> specifying a color in the form #RRGGBB or <GraphicStroke> for a repeated graphic.

Example

Consider the following symbolizer taken from the Simple Point example in the Points section in the SLD Cookbook.

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       <PointSymbolizer>
         <Graphic>
           <Mark>
             <WellKnownName>circle</WellKnownName>
             <Fill>
               <CssParameter name="fill">#FF0000</CssParameter>
             </Fill>
           </Mark>
           <Size>6</Size>
         </Graphic>
       </PointSymbolizer>

The symbolizer contains a <Graphic> tag, which is required. Inside this tag is the <Mark> tag and <Size> tag, which are the minimum required tags inside <Graphic> (when not using the <ExternalGraphic> tag). The <Mark> tag contains the <WellKnownName> tag and a <Fill> tag. No other tags are required. In summary, this example specifies the following:

  1. Data will be rendered as points
  2. Points will be rendered as circles
  3. Circles will be rendered with a diameter of 6 pixels and filled with the color red

Further examples can be found in the Points section of the SLD Cookbook.

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