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Use Case NLL Digitized Map Archive

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NLL Digitized Map Archive


Uldis Bojars (see http://lists.w3.org/Archives/Public/public-lld/2010Oct/0065.html)

Background and Current Practice

The digital version of the Cartographic Collection of the National Library of Latvia (NLL) contains scans of historical maps from the 16th to the 18th century. Currently maps are presented as HTML index pages pointing to PDFs of scanned maps. Index pages contain semi-structured textual information about these maps: title, author, location in a publication, catalogue number, geographic info (scale, cooradinate system) and a transcription of notes on the map.

A new project is planned to digitize ~5000 maps in NLL's collection. These maps will be georeferenced and structured metadata will be associated with maps. A place name (toponym) database will be developed as a part of the project and maps will be annotated with place name information. Existing database of current place names in Latvia will act as a foundation for toponym database, but it will need to be enriched with historical place names used on older maps.


  1. RELATE(new): to enable enrichment of map metadata (e.g., with information about places located on the map)
  2. RELATE(aggregate): pages may contain multiple maps, maps may have various objects on them -- though this information would normally be provided when adding maps to the system. in that case it is not creating new relations (after the data was added) as RELATE would imply.
  3. REUSE-SCHEMAS: reuse existing RDF schemas (DC, SKOS, W3C Geo vocab, ...) for describing maps and objects on them.
  4. REUSE-VALUE-VOCABS: use existing linked data for annotating objects in the system (Geonames is mentioned, VIAF could be linked to as authority data)
  5. URIS: Maps and other objects (areas and objects on maps, points of interest, ...) that the system contains information about are given HTTP URIs so that they can be globally referred to. The use case also describes a toponym database which would provide URIs and linked data about placenames.
  6. PUBLISH: allow users to retrieve metadata (as RDFa or RDF/XML) about digitized maps [enabling users to find and interrelate maps independent of any particular user interface]
-- how is NAME WITH URI different from URIS ?

Target Audience

Scholars, general public, map curators, computer programs.

Use Case Scenario

Visitors to the map archive retrieve map metadata and use them it to find related resources (e.g. other maps from the same publication) or to browse the collection in a novel way. Their work is assisted by applications (e.g., browser extensions) that help in browsing maps and may "mash-up" maps with other information available on the Web (e.g., photos of places).

Map curators or volunteers from general public may annotate maps or regions within maps with additional information (e.g., transcribe text notes or link map locations to place names).

Developers create software programs that access the map archive and provide new services to users. These applications may integrate map information and data from other sources.

Application of linked data for the given use case

Maps and other objects that the system contains information about (e.g., areas on a map) are given HTTP URIs so that they can be globally referred to.

Map metadata can be made available as linked data by using RDFa or by using HTTP 303 redirects to point to various representations of resources and their metadata. Maps are linked to other related resources (e.g. place names or authority data about persons) which may also be expressed as linked data.

Users can annotate maps by publishing RDF statements on their site or by adding annotations directly into map metadata (provided the system allows 3rd parties to update its information).

The toponym (place name) database has a supporting role for this use case. Benefits of making this data available as linked data are:

  • The map archive can refer to placenames using linked data principles. This achieves loose coupling between the applications and each can be developed independent of the other.
  • The toponym database can be enriched by adding relations between entities (e.g., that one entity is contained within another) that could not be expressed if place names were just a simple list of entities inside an application. Data can be further enriched by adding [limited] inference (e.g., over transitional properties).
  • If the system provides URIs that identify geographical locations, anyone can use these URIs in their data and applications. This facilitates information integration.

Existing Work (optional)

David Rumsey Map Collection has over 22'000 historical maps and images online. Map browsing system displays and allows search by metadata. To my knowledge, the site does not provide linked data.

Related Vocabularies (optional)

  • Dublin Core
  • SKOS (for place name, person thesaurus)
  • W3C Geo vocabulary

Vocabularies for other infromation may need to be located or created:

  • dimensions of maps
  • geographic information (geo coordinates, map projection, scale, [historical] units of measurement)

Related datasets that the system could link to:

  • GeoNames
  • authority data

Problems and Limitations (optional)

Vocabularies for describing map-specific metadata will need to be identified. New vocabularies may need to be created if some data can not be expressed using existing ones.

Historical maps use place names that may have changed or disappeared since. This will create difficulties relating locations on the map to a geographical name taxonomy. Such a taxonomy would need to be enriched with historical names and their locations. The area covered by a particular place may have changed as well.

Depending on applicability of OCR to recognizing place names and notes on maps, significant manual annotation work may be involved.

How to handle annotations from users? Shall users be able to change map metadata? If users are allowed to add annotations, an API for adding annotations would be need to be provided.

Related Use Cases and Unanticipated Uses (optional)

Although maps have their specifics, a framework developed for publishing maps as linked data could be reused for publishing other kinds of digital objects (e.g., scanned posters). In a generic case, the same system would be used for publishing any kind of scanned information and map-specific information could be added as RDF annotations using appropriate vocabularies.

Use Case NDNP (National Digital Newspaper Program) is related to this use case as it publishes a scanned and OCRed newspaper archive as linked data.

References (optional)

Electronic version of the Cartographic Collection of the National Library of Latvia, created in 2002:

The Digital Library of the National Library of Latvia: