Layer Styling

By default, Pozi will display layers using generic colours and symbols. Here are options to make your layers more meaningful to users.

Styling Vector Points

Map layers of a small number of point features are best represented by vector points. Most browsers can handle up to several hundred vector points. Vector points enable features to be represented by clickable symbols that are visible at any scale.

You can choose the icons from either of these libraries:

A chart of standard colour names and codes can be found here:

Send Groundtruth the link or name of the icons and the colours you want to use, and we'll configure it for you.

For example:

If you want different colours/symbols for different classes within the layer, provide a simple list of all the class values with the desired symbol and colour.

Styling WMS

WMS is the ideal publishing format for layers with hundreds of features or large regions.

Organisations can control how WMS layers are rendered by by creating a style file and sending it to Groundtruth for publishing (see Publishing section below).

Using QGIS to create layer styling:

  • Open QGIS
  • Layer > Add Layer > Add Vector Layer
  • Double-click layer name to open Layer Properties
  • Select the Style tab on the left


Simple styling:

This dialog is showing styling of a Single Symbol, but there is also the option to create multi-symbols thematic maps by using the Categorised, Graduated, or Rule-Based symbolism.

Please refer to the following document for more details on symbol styling:

Once you have created the style, export it as an SLD file:

Important note regarding Polygon Styling:

Polygons with no fill appear to be rendered by OpenLayers as a border only, with an unselectable hollow centre, ie. the only way to select the polygon is to select somewhere along the border. This is obviously not the desired functionality.

In this circumstance it is suggested that when styling a polygon in QGIS to always apply a fill to the polygon layer, with a 0.01 opacity, such that it is effectively transparent but has a selectable centre.


With the introduction of QGIS 3, labeling configuration created within QGIS is included within an exported SLD. (Previous versions of QGIS do not export any label configuration to the SLD file).  If you require labelling it will be necessary to use QGIS 3 when creating your SLD.


You may also wish to change the font and font size. `DejaVu Sans` is recommended for labelling. It is a 'sans serif' font, which means doesn't have tails at the end of the strokes, making it more legible on a map.


Historically the process has been to upload the SLD file to along with your zipped SHP file (or add the SLD to the dataset at a later date). However, due to issues experienced with using to host the SLDs it has become necessary to find an alternative host.

In the interim, Groundtruth will host the SLDs on its own servers. This means that when you have a new SLD you will need to contact Groundtruth and ask them to load it onto its servers.