INSPIRE Thematic Clusters

OGC Coverage Implementation Schema (CIS) v1.1 already available

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Dear colleagues,

This is to inform you that the new the OGC Coverage Implementation Schema (CIS) v1.1 approved in March 2017 is already available from the OGC site, from the page: http://www.opengeospatial.org/standards/wcs

Concretely:

It specifies a concrete, interoperable, conformance-testeable coverage implementation model based on OGC Abstract Topic 6 (topic equivalent to ISO 19123 abstract model), which:

  • Is independent of the format chosen for the encoding the coverages (e.g. GML, JSON, RDF, etc.), and independent of the service from which they can be accessed - i.e. a Web Coverage Service WCS).
  • Let coverages to be represented by a single document or by a hierarchically organised set of documents (e.g. multipart representations).
  • Allows the encoding of partitioned or "tiled" coverages in space, time or both (in general, in any dimension of the coverage in hand).

Additionally, this new standard is backwards compatible with the previous version of CIS - CIS v1.0 (namely GMLCOV), extending it with additional features, and also compatible with GML.

The document is fully in the scope of data implemented in form of coverages, and therefore in the scope of Elevation, Orthoimagery and other INSPIRE themes using such kind of raster data. 

 

Comments

  • 162 Views
    Emmanuel DEVYS

    Dear Jordi, and all

    I'd like to provide additional information on the CIS 1.1 Coverage model, which allows other encoding than the GML only and also additional Coverage classes as regards the ones in CIS1.0 (= GMLCOV) that is being adopted by ISO TC211 as 19123-2 Coverage Implementation Schema (CIS 1.0, based on existing ISO 19123).

    This new CIS 1.1 Coverage Implementation schema has been standardized by the OGC on basis of 3 encodings in GML, JSON and RDF, and are based on a new Coverage model (whose UML diagrams are provided in html, or other document formats such as pdf or MS word), which is different from the existing OGC AS topic 6 / ISO 19123:2005 (for which a new project has been started). Figure 16 provides a view of the integration of the previous GridCoverage, RectifiedGridCoverage and ReferenceableGridCoverage (coming from ISO 19123 and GMLCOV, and widely used in INSPIRE data specifications for Coverage-based data), and the parallel emergent (as of CIS 1.1) GeneralGridCoverage and GeneralGrid classes. This new UML Coverage model has not been provided to the OGC nor TC211 in order to secure its consistency (both internal and external with other relevant TC211 standards - such as GFM, CRS, ...). This effort has not been done (up to now) because OGC worked on a implementation standard (CIS 1.1) and UML is only informative. The validation of the new UML model has not been done by OGC (under some AS Topic 6), and not by TC211, as of the revision of 19123-1 project, nor integration in the TC211 HMMG model. Consequently, this CIS 1.1 UML model can't presently be considered as standardized, or the people doing so would do it under their own responsibility.

    As (for the GML encoding) the CIS1.1 schema (based on this new Coverage UML model) as updated/changed some Coverage concepts, the name of classes / elements and even the encoding of the coordinates, the "backward compatibility" has been achieved (in order to solve comments sent during the balloting period by IGN, DGIWG, as well as other stakeholders) by inclusion of CIS1.0 into CIS1.1 (see requirement #1 and conformance clause. In fact, the new CIS1.1 schema is not - by itself - backward compatible with CIS 1.0 schema, and the specifications provides no mapping of CIS1.0 elements to CIS1.1.

    Such a mechanism for backward is acceptable in the XML domain, but might create problems for integration in the TC211 HMMG. Therefore I would strongly recommend to consider that the UML description in this "Coverage Implementation Schema" be considered as not formally validated by OGC nor TC211.

    As a result, in the context of INSPIRE, where specifications and schemas are supposed to be derived from standardized (and validated) UML models, I would urge the involved experts and stakeholders to double-check whether the INSPIRE Coverage model has an interest to upgrade to this new model (that is not available as an EA - or equivalent), and evaluate how the existing data specifications may be upgraded / mapped to the new schemas.

     

    Hoping this helps

Elevation, Orthoimagery, Reference Systems and Geographical Grids Cluster

Elevation, Orthoimagery, Reference Systems and Geographical Grids Cluster

INSPIRE Thematic Cluster Elevation, Orthoimagery, Reference systems, Geographical grids - Join this group to share your knowkledge, learn and collaborate in solving issues related to the Elevation, Orthoimagery, Reference systems and Geographical grids themes