The Spatial Data on the Web Working Group (SDWWG) aims to determine best practices for integrating spatial data on the web. It has identified several deliverables including use cases and requirements, best practice recommendations, and completing standards for the OWL Time and Semantic Sensor Network ontologies. Key issues being addressed include representing different levels of spatial metadata, coordinate reference systems, vagueness, versioning, and machine usability. The group plans to finish all deliverables by January 2017.

1. Spatial Data on the Web:
Experiences and outlook
Frans Knibbe - Geodan

3. Spatial Data on the Web Working Group
http://www.w3.org/2015/spatial/wiki

4. SDWWG Timeline
● March 2014: Linking Geospatial Data
workshop
● January 2015: First teleconference
● March 2015: First face to face meeting
● January 2017: All deliverables should be
finished.

5. SDWWG Mission
From the Charter:
1. To determine how spatial data can best be integrated with other data on
the Web;
2. to determine how machines and people can discover that different facts in
different datasets relate to the same place, especially when 'place' is
expressed in different ways and at different levels of granularity;
3. to identify and assess existing methods and tools and then create a set of
best practices for their use;
4. where desirable, to complete the standardization of informal technologies
already in widespread use.

6. SDDWG scope
● Also concerned with OWL Time, so actually it is about
spatiotemporal data;
● Not limited to Linked Data / Five Star Data;
● Mindful of the needs of front end Web developers but
rendering technologies will not be developed;
● Not only for experts.
● Spatial data, not only geographical data;

7. Spatial data
Small kitchen - perspective - textures" by Elektron - Own work. Licensed under CC BY 3.0 via Wikimedia Commons - https://commons.wikimedia.
org/wiki/File:Small_kitchen_-_perspective_-_textures.PNG#/media/File:Small_kitchen_-_perspective_-_textures.PNG

8. Spatial data

9. Spatial data

10. Spatial data
● Eschenbachgasse 9, 1010 Wien
● Αθήνα
● That nice restaurant near the Como lake
● The top drawer of my night table
● pirate.dealings.suppers
● 8FWR6C84+83
● Atlantis?

11. SDWWG Deliverables
1. Use Cases & Requirements (Note)
2. Spatial Data on the Web Best Practices
(Note)
3. OWL Time Ontology (Recommendation)
4. Semantic Sensor Network Ontology
(Recommendation)
5. Coverage in Linked Data (Recommendation)

12. Deliverable: Spatial Data on the Web Best
Practices
It should include:
1. 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;
2. advice on use of URIs as identifiers in GIS;
3. advice on providing different levels of metadata for different usage
scenarios (from broad sweep metadata to metadata about individual
coordinates in a polygon);
4. develop advice on, or possibly define, RESTful APIs to return data in a
variety of formats including those defined elsewhere, such as GeoJSON,
GeoJSON-LD and TopoJSON.

13. Deliverable: OWL Time
The WG will work with the authors of the existing Time
Ontology in OWL to complete the development of this
widely used ontology through to Recommendation status.
Further requirements already identified in the geospatial
community will be taken into account.

14. Space and time
image source:
NASA

15. Why time?
1. The OGC is involved in time (e.g. time series);
2. Serious data sets have serious requirements for time
and space;
3. Time and space have similarities:
○ compare Allen’s Algebra for time (precedes, meets, overlaps,
contains, starts, equals, ...) with the DE-9IM for 2D geometry (equals,
overlaps, covers, crosses, touches ...)
○ different Reference Systems
○ similar requirements for expressing vagueness and uncertainty
4. Spatial Coordinate Reference Systems can be time
dependent

16. ISO 8601
2015-09-14T17:51:31+00:00

17. Deliverable: Semantic Sensor Network
Ontology
The WG will work with the members of the former Semantic
Sensor Network Incubator Group to develop its ontology
into a formal Recommendation, noting the work to split the
ontology into smaller sections to offer simplified access.

18. Deliverable: Coverage in Linked Data
Develop a Recommendation for coverage data, based on
existing work (e.g. ISO 19123, Data Cube Vocabulary).
Coverage: a feature whose properties vary with space
and/or time; for example, the variation of air temperature
within a given geographic region, or the variation of flow
rate with time at a hydrological monitoring station.

19. First deliverable: Use Cases and
Requirements
● 50 use cases
● 57 requirements
● Still some issues to resolve

20. Coordinate Reference Systems
http://www.opengis.net/def/crs/EPSG/0/4326
http://www.opengis.net/def/crs/OGC/1.3/CRS84
http://data.ign.fr/id/ignf/crs/NTFLAMB2E
● Should only geographic CRS be standardized?
● Should there be a default CRS?

21. CRS (1)

22. CRS (2)
image from U.S.
Geological Survey

23. Other issues
● Vagueness
● Versioning

24. Requirements for best practices
● Metadata (bounding box, centroid, CRS,
spatial resolution);
● Linkable, crawlable;
● Usable by machines;
● 3D;
● Tiling (raster & vector), compression;
● Spatial relationships and spatial operators.