Exporting OpenLayers.Layer.WMS to GeoJSON / KML

Question

I'm looking for a way to export a specific region of a WMS layer to some XML format (GeoJSON, GML, KML) using OpenLayers and Geoserver. I've found how to export feature objects with OpenLayers.Format.GeoJSON.write(), but this method only allows converting feature objects or geometry objects.

An example of my idea: I'm viewing a map of a certain country with a couple of WMS layers with some data. Then I zoom to a particular state of that country and I want to export what I'm viewing to GeoJSON or KML for use that in a desktop GIS application (like QGIS).

Does anyone know how to do this?

Thanks.

Answer 1

GeoServer WMS can return data in KML format, since it's a styled format like SVG, but not in GeoJSON, which is instead generated by WFS, since it's just raw data. In order to return KML just make the same request you would have made for a PNG, but ask for "kml" as the output format

Answer 2

Web Map Service (WMS) only deals with images. To 'export' as XML you would need to use something like Web Map Context (WMC) as detailed here :

• http://dev.openlayers.org/docs/files/OpenLayers/Format/WMC-js.html

• http://dev.openlayers.org/releases/OpenLayers-2.12/examples/wmc.html

• http://www.opengeospatial.org/standards/wmc

I'm not sure if Qgis supports the use of WMC though.