Customizing Placemarks

KML output can leverage some powerful visualization abilities in Google Earth. Titles can be displayed on top of the features. Descriptions (custom HTML shown when clicking on a feature) can be added to customize the views of the attribute data. In addition, using Google Earth’s time slider, time-based animations can be created. Finally, height of features can be set, as opposed to the default ground overlay. All of these can be accomplished by creating Freemarker templates. Freemarker templates are text files (with limited HTML code), saved in the GeoServer Data Directory, that utilize variables that link to specific attributes in the data.

Titles

Specifying labels via a template involves creating a special text file called title.ftl and placing it into the featuretypes directory inside the GeoServer Data Directory for the dataset to be labeled. For instance, to create a template to label the states layer by state name, one would create the file: <data_dir>/workspaces/topp/states_shapefile/states/title.ftl. The content of the file would be:

${STATE_NAME.value}

Descriptions

When working with KML, each feature is linked to a description, accessible when the feature is clicked on. By default, GeoServer creates a list of all the attributes and values for the particular feature.

It is possible to modify this default behavior. Much like with featuretype titles, which are edited by creating a title.ftl template, specifying descriptions via a template involves creating a special text file called description.ftl and placing it into the featuretypes directory inside the GeoServer Data Directory for the dataset to be labeled. For instance, a sample description template would be saved here: <data_dir>/workspaces/topp/states_shapefile/states/description.ftl. The content of the file could be:

This is the state of ${STATE_NAME.value}.

The resulting description will look like this:

Warning

Add SS: A custom description

It is also possible to create one description template for all layers in a given namespace. To do this, create a description.ftl file as above, and save it here:

<data_dir>/templates/<namespace>/description.ftl.

Please note that if a description template is created for a specific layer that also has an associated namespace description template, the layer template (i.e. the most specific template) will take priority.