Note: This is the first in a series of posts that examines the next stage of the CIC GDDP project: incorporating maps.
One of the exciting aspects of the CIC Geospatial Data Discovery project is that we are gathering geospatial resources in the form of both GIS records and scanned map images. These two types of resources differ from one another in terms of repositories and metadata standards. Most of our GIS records are from public agencies, such as a state’s department of natural resources and are described with the FGDC or ISO standard. Most of the maps are from University libraries and are described with the MARC or Dublin Core standard. Combining these resources into one portal presents challenges in to form of choosing compatible metadata standards and appropriate tools.
The initial decision of the task force was to convert all resources into the ISO19115 standard. Although this standard is primarily for digital datasets, it can be applied to images. As we began the project, we encountered a few issues that caused us to change our mind:
All of the maps that had digitized versions online used Dublin Core.
- One of our outcomes will be a GeoBlacklight discovery metadata record for each map. This schema is essentially an extension to the Dublin Core standard. Therefore, the process would have involved a transformation from Dublin Core to ISO and back to Dublin Core.
- Most of the digitized maps were harvestable using the OAI-PMH method, which transfers the metadata as a version of Dublin Core.
- Our chosen editor, GeoNetwork, has enabled templates for Dublin Core. We have also been following the work at NYU, which uses Omeka to collect metadata as the GeoBlacklight extension of Dublin Core.
- ISO is a highly nested and detailed metadata standard. The metadata for the scanned maps would only need a small fraction of the standard.
- Dublin Core is a flat standard, which can be easily transformed to other formats, such as spreadsheets.
At this time, we have switched to using Dublin Core as the metadata standard for maps. This decision is not without its own challenges, because the standard includes minimal elements. This means that some fields get reused and do not provide as much specificity as we might like. For example, a Dublin Core record might include a call number, a collection management system ID, a landing page link, and a thumbnail URL. All four of these values would be entered under the Identifier element. Another element that gets reused is Coverage. This field is used for temporal extents, geographic extents, and place keywords.
The GeoBlacklight extension is useful in that it addresses several of the duplicated elements. For example, the extension includes a UUID field that is separate from the Identifiers. There are also separate fields for geographic extents and place keywords.
The GeoBlacklight extension is useful in that it addresses several of the duplicated elements. For example, the extension includes a UUID field that is separate from the Identifiers. There are also separate fields for geographic extents and place keywords.