How to proceed with work on the spatial ontology task?

Dear chairpeople, Josh,

In the teleconference of 2016-04-27
<https://www.w3.org/2016/04/27-sdw-minutes> we discussed the spatial
ontology mentioned in the charter as a part of the BP deliverable. Although
no official actions or resolutions were recorded, we did agree that working
on this topic was needed, that the work would be separate from work on the
BP document, that Josh and I would try to take point and that we would take
the current GeoSPARQL standard as a starting point.

How can we take this forward? Should we first try to form a group of
interested people? Or should we just start somewhere, for example by making
a wish list for a next version of GeoSPARQL, and making that interesting
enough for many people to get involved?

Regards,
Frans