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Prod-Trees Project

Extending netCDF to support enhanced Earth Observation Ontology services (Prod-Trees)

Space Applications Services (B), National Research Council CNR (I), National and Kapodistrian University of Athens (GR)

Access to Earth Observation products remains not straightforward for end users in most domains. Semantically enabled search engines, generally accessible through Web portals, have been developed. They allow searching for products by selecting application-specific terms and specifying basic geographical and temporal filtering criteria. This mostly suits the needs of the general public, but the scientific communities require more advanced and controlled means to find products. Ranges of validity, traceability, accuracy, uncertainty, are concepts that must be taken into account in research activities.

RARE and SMAAD are two such semantically-enabled search engines: RARE permits to search for EO Products by entering terms used by the users in their application domains. In SMAAD, the focus is on the interoperability between the available ontologies: the Web interface allows the users to navigate ontologies and terms that characterize EO products. RARE and SMAAD rely on a preparatory work (ontology mapping, EO product characterization, reasoning rules) that is barely re-usable in other systems without integrating the original software components. Also, they require the EO products to be annotated with controlled vocabularies that have not been standardized. These limitations prevent other organizations (scientific communities, commercial companies) from implementing their own compatible solutions, adapted to their own requirements and application domains.

The Prod-Trees project will enhance the netCDF product format and vocabulary to allow storing metadata that better describe the products, and in particular EO products. It will also extend existing software (official and third-party) for bringing full support of the new format to the community and will demonstrate the results with a prototype software based on the RARE platform.

Project a Glance

The Prod-Trees project is divided in Work Packages that have been grouped in 5 logical parts. Part 0 - which concerns the management activities - is not described further here.

In Part 1, from the start of the project, netCDF and CF-netCDF experts and users will be invited to contribute to the elicitation of the user requirements and the definition of the validation use cases.

At the same time, a state-of-the-art analysis will be conducted on the (CF-)netCDF standard and the related activities, including the standardization, the definition of the metadata model, the applicability to specific domains, and the development of software libraries.

In Part 2, extensions to the netCDF product format will be defined, in particular to address the gaps and the shortcoming of the current standard, and to meet the requirements of the validation use cases. Work on the new controlled vocabulary and the mapping from relevant ontologies will also be conducted.

In Part 3, several software libraries and tools will be updated or implemented during the project. This includes (1) the adaptation of software libraries for supporting the new netCDF products format and (2) the development of a cross-ontology browser and of an EO-netCDF reasoner.

In Part 4, a technology demonstrator will be developed. This will permit to demonstrate at the end of the project the novel capabilities of the new netCDF extension.

Parts 1 and 4 start at the beginning of the project. Part 4 is performed all along the project. Parts 2 and 3 are performed simultaneously, after the end of Part 1.

Part 1

State-of-the-Art and Project Definition
• User Requirements
• Validation Use Cases
• State-of-the-Art
• Enhancements Specification

Part 2

Knowledge Engineering
• Vocabulary Enhancement
• Ontology Mapping

Part 3

Software Engineering
• Libraries Design & Implementation
• Ontology Browser & Reasoner

Part 4

Technology Demonstrator
• Prototype Requirements
• Prototype Design & Implementation
• Prototype Testing & Validation

Objectives and Benefits

The project will bring a standardized solution that permits annotating EO products, in netCDF and related conventions, in a manner that official and third-party netCDF software will be able to search for products using advanced tags and controlled parameter names.

Annotated EO products will be automatically supported by software compatible with the extended netCDF standard. The entire product information will come from the annotations and the standards and there will be no need for integrating extra components and data structures that have not been standardized.

In the course of the project, the most important and popular open-source software libraries and tools will be extended to support the proposed netCDF extensions. The result will be provided back to the opensource community for ensuring the best dissemination and adoption of the extended format.

Application and Result Expected

The following results are expected from the Prod-Trees project:

  • Definition of EO Conventions for netCDF (EO-netCDF) compliant with other relevant conventions including CF Conventions and Uncertainty Convention (netCDF-U)
  • Definition of the EO Vocabulary and its publication as SKOS/RDF accessible with a SPARQL interface
  • Mapping of the EOP O&M onto the EO-netCDF
  • Mapping of ISO 19115-1/2 onto the EO-netCDF basing on previous works (ncISO, and GI-cat data model)
  • Extension of netCDF Java APIs to fully support the EO-netCDF
  • Extension of GI-cat, GI-axe and GI-sem framework to support discovery and access of EO-netCDF datasets
  • Enhancement of the RARE system to allow semantic queries based on several ontologies to discover EO-netCDF datasets
  • Ontology Browser and Reasoner for EO-netCDF

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