Charts for raster layer

[gannebamm]

Description

The chart widgets do not work for raster layers. I would like to create e.g. barcharts for categorical rasters like CORINE Land Cover (https://land.copernicus.eu/en/products/corine-land-cover). The WPS process from GeoServer should be able to use WCS as input for the gs:aggregate function (https://docs.geoserver.org/main/en/user/services/wps/processes/gs.html) even though there is no example of the usage listed in the documentation.

Acceptance criteria

• Bar charts can be created with rasters

Other useful information

We will try to implement this as part of Thuenen-GeoNode-Development/thuenen_atlas#29

If there are any preliminary works or experience in that regard, please notify us.