1. HMA Follow On Task 1 Standards evolutions
HMA-FO Workshop, 29 September 2009, Fraunhofer (Darmstatd)
Frédéric Houbie, ERDAS
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2. Reminder
HMA objectives and solutions regarding metadata structure and discovery.
Objective 1 - Metadata format : define a common metadata format to store earth observation product metadata information.
Objective 2 - Metadata catalog: store the product metadata in a catalog and allow a user to discover products based on some criteria.
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3. Metadata format
Requirement: the metadata format should be extensible to store all kind of products (present and future).
The ISO format was proposed but it does not allow to store earth observation business information nor defining easily new kind of products.
A new format EO GML was defined to store earth observation information.
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4. EO GML The EO GML is a profile of the GML standard.
The EO GML format allows to easily create new kind of products by extending existing ones.
EO GML contains information about
The products
The acquisition platform
The archiving station
The browse and mask information
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5. Metadata catalog
Requirement: The catalog should be generic to store different kind of metadata (ISO, SensorML). It should be extensible to allow storing new kind of EO products.
The OGC CSW-ebRIM catalog was chosen for its extensibility features using Extension Package.
A new Earth Observation Extension Package defines the Earth Observation model to store in the CSW-ebRIM catalog.
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6. HMA-T2 feedback
The EO GML and EO Extension package was created during the HMA initiative.
This solution is flexible, business oriented and interoperable.
Based on the HMA-T phase 2 experience, several points could be improved to make the solution more robust and extensible.
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7. First issue
The first issue: “Large number of requests needed to retrieve all the products metadata matching some criteria ”
First the client sends a GetRecords request including the search criteria to get the matching EO Products (in ebXML).
Then for each received product, a GetRepositoryItem request is send to retrieve the EO GML.
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8. Second issue
The second issue: “Complexity of the EO model structure with information not used for the discovery”.
All the information of the EO GML metadata are mapped in the EO Extension Package model.
The structure of the model is well designed but contains a lots of information not needed for the discovery of products.
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9. Third issue
The third issue: “Evolution of the EO Extension Package is unmanageable since all the EO GML attributes are mapped to the EO model.”
Since all the EO GML attributes are mapped to the EO model, a simple change in the EO GML must be reported to the EO model (either if not needed for discovery).
The Extension Package must be updated/extended for each new product types.
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10. Fourth issue
The fourth issue: “Redundancy between EO GML and SensorML regarding the acquisition platform”.
Now, the SensorML metadata format allows to precisely describe an acquisition platform (like a satellite)
We need to harmonize EO GML and SensorML regarding the acquisition platform metadata.
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11. Proposition 1
Simplify the model with the minimal information needed for discovery
Simplify the structure: only EOProduct and EOAcquisitionPlatform are usually needed for discovery.
Remove some attributes (like orbitNumber of processorVersion) not needed for discovery.
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12. Proposition 1
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13. Proposition 2
Allow to piggyback the metadata in a CSW GetRecords response.
We must extent the CSW-ebRIM spec to include the metadata in a GetRecords response
using RepositoryItemRef and MIME-Multipart like for Transaction Insert request.
The metadata are piggybacked if the elementSetName (view mode) is equal to full.
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14. Proposition 3
Replace the EOAcquisitionPlatform by a SensorML platform.
We need to create the Sensor Extension Package.
We need to describe platform in SensorML metadata format
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15. G-Hmafo-Task1@spacebel.be http://wiki.services.eoportal.org/
Summary
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