INSPIRE Coverages: From Mystery to Mastery

EU member states shall implement the INSPIRE directive by 2020, says the INSPIRE roadmap. Still, there is a significant amount of uncertainty especially on coverages, that is: raster data and services: Here is the good news: it's not that difficult actually, know-how and technology is available! This site educates on and demonstrates INSPIRE coverage services, established by a team of key OGC and INSPIRE experts and powered by OGC-certified rasdaman.


Coverages and WCS: Basics

So what is a coverage? Coverages are the worldwide accepted concept for representing raster data, used by OGC, ISO, and INSPIRE (they can also represent point clouds and general meshes, but typically focus is on raster). OGC maintains a large collection of tutorials, webinars, and working examples in the coverage data and service model.

The coverage data model: A coverage consists of a domain set ("where are the data located?"), a range set (the pixel payload), a range type ("what is the semantics of these data?)", and some arbitrary metadata ("what else should I know about these data?"). While OGC and ISO agree on an interoperable coverage definition with broad format encoding support, INSPIRE has established its own, non-interoperable definition which is causing significant confusion in the INSPIRE community; moreover, this coverage model contains several technical flaws, and some experts also consider it unnecessarily complicated. We have made a proposal to realign with OGC and simplify INSPIRE coverages, with corresponding schemas amending the OGC Coverage Implementation Schema (CIS) 1.0 with INSPIRE metadata for orthoimagery, elevation, and land cover.

The coverage service model: The INSPIRE WCS Technical Guidance mandates OGC WCS Core and optionally adds OGC WCPS. As OGC WC(P)S operates on the OGC coverage model, INSPIRE WCS consequently operates on the OGC coverage model, Coverage Implementation Schema (CIS), and bypasses the INSPIRE coverage definition. However, such coverages must duly contain INSPIRE metadata in the coverage's metadata compartment, in coherence with the OGC CIS and WCS provided extension mechanisms. The open-source rasdaman engine used by this portal is OGC WCS certified and, at the same time, provides proper INSPIRE metadata.

OGC OAPI-Coverage: Currently an effort is underway to unify OGC feature, coverage, map, and processing services based on the OpenAPI concepts. From a WCS perspective, this is an evolution, not a disruptive replacement: first, the new OAPI-Coverage specification is based on the OGC Coverage Implementation Schema (CIS) 1.1. Second, effort is devoted to maintain coherence - OAPI-Coverage from a WCS perspective should resemble just another "protocol binding" which can be used interchangeably with GET/KVP, POST, and SOAP.

The OGC/ISO Coverage ecosystem: The coverage data and service model, including OAPI-Coverage, form a powerful, versatile ecosystem of coverage functionality. The following diagram shows the complete WCS suite with its components and their relationships:


Conformance testing: OGC provides a rigorous conformance test suite validating implementations down to pixel level. The INSPIRE conformance test inspects validity of INSPIRE metadata; all other properties are addressed by the OGC conformane tests. Hence, an INSPIRE conformant WCS implementation must pass both tests.

Coverage standards: The authoritative source for coverage data is the OGC Coverage Implementation Schema, which is also ISO standard (ISO 19123-2:2018) and (via WCS) also authoritative for INSPIRE. Further definitions, such as by W3C or definitions solely relying on the abstract model of ISO 19123, are not authoritative, not interoperability-proven, not as rigorously implementation-tested as OGC CIS is, and not with the multitude of implementations supporting it. OGC/ISO coverages can be served via OGC WCS/WCPS (which has the most dedicated coverage functionality), but also OGC WMS, WPS, and SOS.

More on INSPIRE Coverages

Questions? Need Help?

Contact us - we gladly share our experience and insight from many years of writing and implementing OGC, ISO, and INSPIRE standards.

This service demonstrates use of coverages and WCS/WCPS for several INSPIRE themes, powered by the rasdaman WCS reference implementation and offering data provided by Institut Cartogràfic i Geològic de Catalunya (ICGC). Bringing INSPIRE coverages to life is a passion of the "gang of three" (in inverse alphabetical order), supported by the rasdaman team:

This service is for demonstration purpose only. It does not offer authoritative data nor services, and it may not be used for any kind of geospatial decision making.

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