Q:

Geoserver WMTS Tile Metadata

I am using Geoserver to deploy a WMTS service with the help of an already existing WMS service. In general it works out well but i need to add some "terms of use". Is there a way to add something like that to the metadata of the tiled images (png) or to watermark the tiles?

A:

WMTS doesn't really have the concept of metadata associated with tiles, the best you could do is a note in the layer abstract which would appear in the capabilities document (and is unlikely to be read by a human).
One possibility for watermarking is create a polygon layer that is larger than your existing WMS layer, then create a graphic fill for it using your watermark using a graphic-margin to spread it out if necessary. Then combine the two layers in a layer group so that it is suitably watermarked in the tiles. Make sure to mark the WMS layer as not Advertised to prevent people requesting it without the marks.  

