This demo shows querying of pixel data.
Selected pixel value (RGBA): none selected
Area selected: none
This example uses a OpenLayers.Raster.Operation
to query composite data from a WMS layer. Click on the map to
query pixel data. The results of the query are displayed on
the map as a OpenLayers.Layer.Raster.
See the raster-query.js source for details on how this is done.