Houbie F

Marchetti P-G

Martin J

Smolders S

Woolf A

English

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Geophysical Research AbstractsVol. 12, EGU2010-14875, 2010EGU General Assembly 2010© Author(s) 2010The ESA GML Application Schema for EO Products: extension to newproduct typesAndrew Woolf (1), Steven Smolders (2), Frédéric Houbie (3), Jolyon Martin (4), and Pier Giorgio Marchetti (4)(1) STFC Rutherford Appleton Laboratory, Harwell, UK, (2) Geographic Information Management (GIM), Heverlee,Belgium, (3) ERDAS, Liège, Belgium, (4) ESA ESRIN, Frascati, ItalyThe Heterogeneous Missions Accessibility (HMA) project is a joint activity of the European and Canadian SpaceAgencies lead by ESA through its Ground Segment Coordination Body (GSCB). It aims to provide a seamlessand harmonised access to heterogeneous Earth observation (EO) datasets from multiple mission ground segments.To achieve this goal of interoperability, the HMA project is developing standardised metadata descriptions atcollection- and product-level, as well as standardised network service interfaces for data discovery, ordering,planning, user management, and data access. These interfaces will be implemented in the EO Data Access andIntegration Layer (DAIL), providing an integrated, harmonised access across multiple mission ground segments.A standardised description of EO data products is provided through a GML Application Schema for EOProducts, endorsed as a Best Practice paper (06-080) by the standards body, Open Geospatial Consortium (OGC).Product-level metadata conforming to this schema may be ingested into an HMA standard catalogue serviceimplementing the ebRIM profile of OGC’s CSW interface with an extension package for EO products (OGCdocument 06-131). The GML application schema is based on the GML observation, adding detail to the followingproperties for an Earth observation:• general metadata describing identifier, downlink, archiving information, etc.• the acquisition duration• the platform/instrument/sensor used for the acquisition, and other acquisition parameters• the observed ground footprint• the observation result (browse, mask, and product descriptions)In addition, the schema takes a layered form: a foundation ‘Earth Observation’ schema is applicable for anytype of EO product, with more specialised schemas derived from this for specific product types (optical, radar,atmospheric) .We report on new work sponsored by ESA (in the ‘HMA Follow-On’ project) which is extending the ex-isting application schemas to additional product types: altimetry, limb-sounding, and ‘synthesis’ products. Theseproduct types present new challenges for the application schema. For limb-sounding products, the verticalsampling geometry is as important as a ground footprint, and the observed property (e.g. radiance, spectra, orderived geophysical parameters) is a crucial part of the description. For altimetry, along-track products have a verydifferent footprint geometry to gridded products. Systematic and synthesis products are derived from multiplesource EO products, with the range of geophysical product types demanding a rigorous use of controlled terms.As well as the metadata extensions themselves, new implementation techniques are being considered. First,the model-driven approach enhances quality by maintaining a single normative artefact (a UML model), withGML application schemas and documentation automatically derived. Second, a new standard (ISO 19156) onObservations and Measurements is likely to be adopted as a replacement for the GML observation model onwhich the EO schemas have been based. Third, parallel work on an EO data access service and the new releaseof a GML-based OGC Web Coverage Service specification, offers the potential for harmonisation between theproduct metadata and exploitation metadata.

The ESA GML Application Schema for EO Products : extension to new product types

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