Introduction

The SDWWG charter mentions that the Best Practices deliverable will include

"an agreed spatial ontology conformant to the ISO 19107 abstract model and based on existing available ontologies such as GeoSPARQL, NeoGeo and the ISA Core Location vocabulary"

The purpose of this page is to collect ideas on

• Why developing an agreed spatial ontology would be a good or bad idea
• How development of an agreed spatial ontology could take place
• Requirements for the agreed spatial ontology

Please feel free to restructure this page if you want to share an idea for which there seems to be no place.

Definition

What is a spatial ontology? Some ideas are gathered in this W3C Geospatial Incubator Group report.

The list of requirements for a spatial ontology, i.e. the description of what is is supposed to do, can also serve as a definition.

Why

An agreed spatial ontology could help to:

• Provide a bridge or common ground between geographical and non-geographical spatial data.
• Provide a foundation for harmonization of the many different geometry encodings that exist today.
• Provide basic semantics for the concept of a reference system for spatial coordinates.
• Provide a link between W3C standards and OGC standards.
• Define a basic datatype, or basic datatypes for geometry.
• Agree on how geometry and real world objects are related and how different versions of geometries for a single real world object can be distinguished. For example, it makes sense to publish different geometric representations of a spatial object that can be used for different purposes. The same object could be modelled as a point, a 2D polygon or a 3D polygon. The polygons could have different versions with different resolutions (generalisation levels). And all those different geometries could be published with different coordinate reference systems. Regardless of geometry encoding, we need agreement on how to relate different geometries with different characteristics to an object/resource.

A risk is that the agreed spatial ontology will be yet another standard next to the numerous standards that already exist (see https://xkcd.com/927/)

How

Options for developing an agreed spatial ontology are:

• Start with the current GeoSPARQL standard. As an OGC standard based on W3C standards, it already is a bridge between the web world and the geospatial world. The current set of BP requirements could be used to investigate if and how GeoSPARQL could be improved or extended. This approach is described in Further development of GeoSPARQL.
• Start with the official ISO/TC 211 OWL implementation (https://github.com/ISO-TC211/GOM/tree/master/isotc211_GOM_harmonizedOntology).
• Start with a mathematical description of geometry and reference systems. At a minimum, this could include a definition of a point in one, two or threedimensional space, and a definition of a coordinate system (which can be considered a special geometry). More elaborate models could be bases on those foundations (e.g. a line or polygon as a sequence of points, cartesian and spherical coordinate systems,...). This approach could reduce the risk of ending up with an ontology that is useful for only some specific use cases, because modelling will not be based on any use case.
• Start with the W3C basic geo vocabulary.

Requirements

The following requirements for the spatial ontology can be considered:

• It must be as simple as possible.
• (Therefore) it must have a modular or layered structure, so users won't be bothered with things they don't need.
• It must evaluated by relevant communities.
• It will help data providers, data consumers and developers of software for data storage and data processing.
• It can be used to underpin as many current standards as possible.
• It must be extensible.
• It must be a standard/recommendation from both OGC and W3C.