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ISAW Papers 7.9 (2014)

Beyond Maps as Images at the Ancient World Mapping Center

Ryan Horne

Background

When the Barrington Atlas (Talbert and Bagnall 2000) reached publication in 2000, it represented the culmination of nearly a decade of development using both traditional cartography and modern GIS systems, providing the first comprehensive coverage of ancient Mediterranean geography since Smith and Grove (1872). The atlas features 102 maps, extensive metadata in a map-by-map directory, and served as the catalyst for the establishment of the Ancient World Mapping Center (AWMC) at the University of North Carolina, Chapel Hill and for the subsequent development of the Pleiades Project.

The goals of the AWMC are in part to refine, expand, and curate the data created for the atlas, to continue research into ancient geography, and to present data in an accessible, instructive form. This includes the production of maps for publications and larger projects such as a series of wall maps. It was during the production of the wall maps that limitations to the AWMC's previous approach of primarily viewing maps as flat images became readily apparent. The sheer scale of the project, coupled with the myriad changes suggested by reviewers, revealed the necessity of an easily reproducible, readily searchable, and scalable system to display and sort the over 200,000 individual objects residing in the center's database. As an outgrowth of this realization, the AWMC began an initiative to create an end-user customizable web application to generate maps and replace the older static images provided by the center. The first result of these efforts, the Antiquity À-la-carte application, was launched in March 2012 with a major update following in October of the same year.

In order to complete these projects, the AWMC began to catalog, analyze, and offer its data to the larger scholarly community under a Creative Commons CC BY-NC 3.0 license. AWMC's data is primarily geographic and contained within Shapefiles, with coastlines, water coverage, water courses, and other natural and human constructed features adjusted for their state in the ancient world. All of the data was initially offered as Shapefile and GeoTiff downloads that presented easily accessible resources which nevertheless had severely limited potential for dynamic linking, searching, and other complex interactions. Further steps were needed to move beyond these largely static data sets.

As the AWMC is partnered with the Pleiades project, the association of geographic items with Pleiades IDs coupled with a database-driven interface was the obvious next phase in the evolution of the center's offerings. Key to this step was the creation of an interface and the modification of the AWMC's data in order to adhere to URI best practices and 5-star principles as outlined by Tim Berners-Lee (1998 and 2007), including permanence, simplicity, and a naming scheme that is agnostic to the underlying content of data. The alignment of the center's resources with Pleiades IDs for all features, along with adding custom metadata where appropriate, became the foundation for the center's movement towards these goals. The first step at the AWMC was the creation of a PostGIS database to house and display Pleiades data, which is followed by the use of GIS software to identify and add appropriate metadata to the Shapefiles produced by the center (a task which is largely done by hand), then the subsequent importation of completed Shapefiles into the PostGIS database. As this work was underway, a further step towards deeper integration with the linked data community occurred in January 2013, when the AWMC created an API interface to its database using RESTful URIs and joined the Pelagios Project. Due to the earlier use of Pleiades IDs, creating the relevant RDF files and linking to the Pelagios system proved to be a trivial matter (for further technical discussion on the linkages of the AWMC to Pelagios, please consult the AWMC blog post on the Pelagios site).

Results

An example of the API and linkages can be found at http://awmc.unc.edu/api/omnia/168940, representing the urban area of Rome c. 200 CE. The default splash page is generated dynamically by PHP with a PostGIS backend, presenting a reference map, links to Pleiades and Pelagios, and general information on the entry in a human-readable format as shown below:

AWMC API image

Any entry in the database can easily be displayed in JSON, RDF, or WKT by clicking on the provided buttons or appending the desired representation to the end of the base URI as follows:

Each one of these links leads to a dynamically generated page that presents the desired format and content. This grants easy access to the center's data without creating a local data dump or mirroring data in a remote machine, and can be consumed directly by mapping libraries such as OpenLayers.

The current iteration of Antiquity À-la-carte deploys the results of the API work by providing a web-based GIS application to display, sort, search, and disseminate the center's data. The application is built upon a suite of GIS technologies, exports a user-created map into GeoJSON, KML, CSV, and PDF formats, and can import a custom map generated from GeoJSON objects. The application also allows for the selection of different display languages, time periods, and the creation of new features to meet a user's needs, along with offering a set of interactive tools and in-map linkages to Pleiades and Pelagios content.