CDI Extensions for seismic data
In the case of seismic data it was necessary to make significant changes to the CDI metadata format to accommodate this data type. However, it was also highlighted that significant extensions to the CDI could potentially lead to the ‘speciation' of the CDI. This would then be detrimental to the ability of the CDI to be a single tool which is applicable to a diverse range of data types. Therefore in order to accommodate the additional content fields which were required for the geophysical data types, it was decided to extend the CDI format with Observation & Measurements and SensorML schemas, whereby the linkages between these and the CDI is being provided by URLs. The O&M schema can contain the additional content fields, so called "user metadata", required for describing geophysical data such as seismic and side scan sonar which are supported by the common vocabularies. The resulting extended format is documented in a technical document.
The adoption and implementation of the extended seismic format required a further upgrading of the MIKADO metadata XML editor tool. Upgrading of the central CDI portal applications was not necessary because the O&M and SensorML XML objects are to be managed at the data providers and can be retrieved using URLs whereby 1 CDI links to 1 O&M linking to 1 to many SensorML files. The Seismic CDIs can also give access to thumb nail low resolution images of the seismic data for previewing, before users decide to request access to the high resolution data using the CDI shopping mechanism.
Seismic data has a specific commercial value. Therefore access to the high resolution seismic viewing service needs to be regulated because seismic data are normally only accessable to users after positive negotiation with their data providers. To account for this it was decided to develop also a high resolution viewing service for seismic data as an alternative to the downloading service. Therefore a web based viewer application has been developed that has to be installed at the data centres to give users regulated access for viewing seismic data that are managed at these data centres. Activities are now underway for integrating the high resolution seismic viewing service into the CDI Data Discovery and Access Service and for installing and configuring the service at the seismic data centres. It is foreseen that this alternative service for accessing these type of data sets will be operational from November 2012 onwards.