Workshop Report
Digital Gazetteers: Integration into Distributed Digital Library Services
ACM-IEEE Joint Conference on Digital Libraries
Portland, Oregon
July 18, 2002
By Linda Hill
Alexandria Digital Library Project
University of California, Santa Barbara,
lhill@alexandria.ucsb.edu

A workshop on Digital Gazetteers: Integration into Distributed Digital LibraryServices was held on July 18, 2002 in conjunction with the ACM-IEEE Joint Conference
on Digital Libraries in Portland, Oregon. This workshop was sponsored by theNetworked Knowledge Organization Systems/Services (NKOS) group as the 5th in theirworkshop series: see http://nkos.slis.kent.edu/. The 38 participants represented aworldwide community of researchers, implementers, and librarians for whom gazetteers
are important components of information systems. These included those from cultural
history, biology and environmental data collections, library cooperative projects, digital
library research, information service companies, and state and national projects related togazetteers. Participants came from Germany, Taiwan, Norway, Canada, and the United
Kingdom as well as the United States. Presentation slides from the workshop areavailable on the NKOS website through the link to the workshop.
Linda Hill, University of California – Santa Barbara (UCSB), presented the basicelements of a content standard for gazetteer data, pointing out that gazetteers are a type ofreference tool along with thesauri, dictionaries, taxonomies, and so forth that arecomponents of digital libraries, valuable for their role in establishing meaning andnavigating collections. Details of representing placenames, geographic location (inlongitude and latitude coordinates), and type were discussed and issues of fuzziness ofplace and time and the need for community-based support for gazetteer content standards
and typing schemes. Different structures for gazetteer data were compared: thesaurus
structure vs. metadata-like structure and the ISO specification vs. the Alexandria Digital
Library (ADL) model. The issue of the ranking of places in terms of their “importance”
was raised.
Jim Frew, UCSB, presented an overview of the Textural-Geospatial Integration (TGI)
Project, part of the NSF’s National Science Digital Library initiative. The goals of thisproject are (1) geospatially-augmented search and (2) geospatially indexing documents.
Text documents (includes query statements, metadata, full-text documents, etc.) are theinput for TGI. Geographic parsing, thesaurus and gazetteer lookup, analysis ofgeographic “facts”, and evaluation to select the “best” data are the major components of
the TGI process. The goal is to have a service to which you can submit a document andget in return geospatial locations and alternative placenames that are ranked as best, alsorans, and alternatives.
Ruth Mostern, Berkeley, presented the work of the Electronic Cultural Atlas Initiative(ECAI) toward developing digital gazetteer standards for history and culture. They are
not focusing on building a gazetteer, but on adapting and developing a content standard,feature type thesaurus, and best practice guidelines for their global, multilingual
community of historians and humanities scholars. Language, cultural perspectives,
uncertain information about historical places and their names and locations, scholarly
documentation, and changes through time are all challenges for developing community
standards in this domain.
Greg Janée, UCSB, presented work on the development of gazetteer and thesaurus
protocols to support search and retrieval over distributed resources. The gazetteer
protocol is also designed to handle the submission of new and modified data to agazetteer. These protocols are lightweight and stateless and operate over HTTP toencourage implementation. Queries and reports are specified in XML and a small numberof basic services are supported. The two protocols are complementary. The ADL modelof gazetteer data is used and the model for thesaurus data is based on the NISO Z39.19
standard. The issue of standard relationship types between gazetteer entries was raised:should a small set of basic relationships be adopted? should they reside in the server orthe client? should the protocol allow multiple relationship types?
Jens Fitzke, University of Bonn, presented his gazetteer protocol work. It is structured
within the framework of the Open GIS Consortium (OGC), which has close liaison withthe ISO TC 211 standards work supporting georeferenced data. The OGC Web Gazetteer
Service is built on the OGC Web Feature Service and adopts the model of gazetteer
specified in the ISO TC 211 DIS 19112 standard for spatial referencing by geographic
identifiers. Unresolved issues include handling feature changes over time. The issue ofhow to harmonize the two gazetteer service approaches was raised.
Dagobert Soergel presented a report on current NKOS activities sent by Gail Hodge. Of
note is that NISO is planning to revamp the wording of their Z39.19 thesaurus guidelines
to be more accessible to non-lexicographers and to reissue the standard without extensivechanges. Discussion questioned the wisdom of this move since discussions have alreadybeen held to identify the important changes needed for the standard.
Ya-ning Chen (Arthur Chen), Academia Sinica, presented work toward a digital gazetteer
service in the context of Chinese culture. He compared the support for gazetteer
information in three standards representing the approach of a digital library, a museum,and the library world: the ADL Gazetteer Content Standard (GCS), the Thesaurus of
Geographic Names (Getty), and USMARC standard. They have translated much of theGCS into Chinese and have added links into a GIS system and to the map layers that
contain the place, perhaps at different scales of resolution. Representation of change innames and in location through time is an important factor. Results of this work include anonline Taiwan gazetteer, online Chinese Civilization in Time and Space, an XML testbed

for the GCS, a Chinese version of the GCS, and a set of feature types for Taiwan. Future
work includes development of a hybrid approach to the use of GCS, TGN, and USMARC
gazetteer data; gazetteer sharing services for file exchange and distributed retrieval, andthe development of relationship attributes for gazetteer entries.
James Reed and Andy Corbett, Edinburgh Data and Information Access (EDINA),
presented the UK Geo-Crosswalk project whose aim is to develop gazetteer services for
the UK tertiary education and research community. Their approach, based on ADL, is tosupport geo-parsing and enhanced geospatial searching and provide reference services,
metadata creation services, and tools for spatial searching for the academic communityand beyond. Technical issues stem from the variety of sources that need to be used fromplacename and geometry data and include complexity, feature typing, positionalaccuracy, alternative names, time stamping, and incompleteness of data. Licensing is also
an issue. They have developed their own spatial searching software which is being usedwith an Ingress database.
Humphrey Southall, University of Portsmouth, presented the Great Britain Historical
Boundary Project which includes a gazetteer component but is much more than that. This
raises issues of the degree to which their gazetteer component can be compliant with theADL GCS. A fundamental problem with the analysis of social statistics through time isthe complexity of changes in administrative boundary and organizational hierarchies.
This project seeks to improve the metadata documenting these boundary changes and todevelop an integrated and comprehensive gazetteer/place-name authority list forhistorical administrative units in Great Britain, linking information about the same placefrom different sources (primarily census data). They are basing their system on an Oracle
database and their spatial search datablade and GeoTools open-source visualization
toolkit for the client. Complexity and abundance of the census data available is a major
issue, as is adopting the social science Data Documentation Initiative (DDI) standard for
representing details of survey data. Other issues include anticipating the number of users
and their uses for their website; implementing ADL GCS in such a large, complex systemwith time-variant footprints; developing a set of feature types for their administrative
categories; language-specific preferred names; supporting both longitude/latitude andgrid spatial geometries; the degree to which the statistical data resides in or out of thegazetteer structure; and explicit relationship types among entries.
David Smith, Tuffs University, presented his work on mining gazetteer data from digital
library collections done as part of the Perseus Project. Here one challenge is to recognize
placenames in parallel corpora in different languages; e.g., an English translation of an
original Greek document. Knowing this mapping is an aid to aligning the text of the twodocuments. In a fashion similar to the way in which words and their meanings are
extracted from texts for dictionaries (a process known as “slipping”), the proposal here isfor text to be mined for their placenames and variant forms of the placenames, especiallyvariant language expressions for those placenames, and to populate gazetteers with thisknowledge. Interesting statistics on the nature of placenames has come out of their work,
showing cultural/locational differences in the frequency of multiple names for the sameplace versus the frequency of the same name designating different places. Recall andprecision measures on the effectiveness of their methods for identifying placenames intext in different languages show high performance in the range of 0.89 to 0.96 (F measure
combining recall and precision measures).
Patrick McGlamery, University of Connecticut, presented his work involving the use ofdigital cartographic sources to estimate the geographic extents for 718 named populated
places in Connecticut, some of which have naturally indistinct boundaries that cannot beobtained from official sources. The process involved starting with the populated placename set from the USGS GNIS dataset for Connecticut, which includes point location
data only, and a set of satellite imagery which has been processed to represent Land Use /Land Cover (LULC). The LULC data classify the terrain into classes; two of the classes,"residential" and "rural residential," were used for this analysis. The process resulted in
258 successful matches of GNIS points with single residential polygons. Unsuccessful
matches included 193 instances of multiple points per residential area and 267 points
with no corresponding residential polygons. Many of the latter places were named"Corners" indicating, perhaps, minor populated places at road intersections. The process
is considered to be a satisfactory way to obtain polygon boundaries for gazetteer data, but
it must include local authentication. Since there were also residential areas identified forwhich there was no GNIS populated place entry, additional analysis into if or how they
are included in GNIS is necessary.
Rhian Evans, Atlas of Canada, presented the current activities of the Atlas of Canadaproject and some of the issues they have encountered that are related to their gazetteer
services and “find a place” application. Both the Atlas project and the Canadian
Geographic Names Service (CGNS) operate under the umbrella of the Canadian
Geospatial Data Infrastructure (CGDI). Challenges for the Atlas project include problems
with the structure and content of the CGNS and duplicate names for the same featuresthat show up in other sources; relationships between the data in different GIS layers;
features with fuzzy boundaries (e.g., bays); and data tagged at different scales. The CGDI
gazetteer services attempts to perform “on the fly” linking of placenames to feature datain the Atlas. Multiple sources of data (e.g., census data, environmental data) are linked toa particular feature. Future plans include adding names for features such as healthdistricts and ecozones and adding additional thematic layers to the Atlas.
Cliff Lynch, executive director of the Coalition for Networked Information (CNI),
summed up the workshop and led the discussion period. He began by pointing out thetension that gazetteers present between the view that language (placenames) is a nuisanceto real geography and the view that named geographic places represent more thangeometric inclusion. He cautioned against the desire of some to have gazetteers include
encyclopaedic knowledge about places rather than serving their role as reference sourcesthat link or provide access to extensive datasets and publications about those places.
There are nasty engineering problems to deal with, including persistent IDs whenreferencing texts. An important short-term goal should be to deal with the issues of
distributed gazetteers, dealing with issues of scooping, provenance, and versioning. Hecautioned against combining in one gazetteer service protocol the search and retrieval
functions with the submission and update functions; much more agreement among parties

is required for update than for retrieval. There are questions about how much context tocarry with gazetteer queries. Experience with Z39.50 should be considered; moving
elaborate semantics can be tricky, with implications for processing speed and usefulness.
On standards development, he supported the role of ground-up standards processes whereapplications and implementations make the case for adoption by others. A killerapplication can make the case for such a standard. He pointed out that simple
visualization of documents geographically is a mere party trick; the real value ofgeoreferenced information services lies in finding associated concepts and doing query
expansion and assisting in cataloguing and metadata creation. He suggested that theNational Science Digital Library initiative offers an opportunity for local gazetteer
development driven by the needs of education. Data quality issues that are revealed
through geographic access is an intriguing issue.
The discussion period was lively and can’t be completely summarized here. Topics
included (1) security and privacy issues with gazetteer data; (2) importance of feature
type schemes for information description and retrieval; need for customized/localizedfeature type schemes; interoperability of such schemes; tension between complexity andsimplicity in these schemes; (3) announcement about the ESRI gazetteer services
available free over the Internet and the distinction between placenames and addresses –geoparsing vs. geocoding; and (4) interest of CNI in gazetteers; increasing interest instructured reference sources.
In addition to the workshop proceedings, Jordan Hastings, UCSB, gave a presentation on
duplicate detection challenges for gazetteers at a Workshop Preview session the evening
before the workshop. He presented his work on developing a methodology for comparing
gazetteer entries to determine if they are about the same place. This is a difficult
challenge because no single piece of data about a place is unique: the same names can belinked to different places; a place can have multiple names (sometimes because ofdifferent languages, variant spellings, and changes through time); geometries come indifferent forms (e.g., points and polygons) and at different scales, from different
suppliers, and for different time periods. Types can also vary, and have differing
hierarchical levels of representation, but have proved to be the most reliable clue for
duplicate detection. The methodology uses a weighted combination of measures based on
a comparison of types, locations, and names. Other factors that might improve
performance is whether the feature can be expected to have a crisp or diffuse boundary;whether the feature’s geometry is compact or extended; and whether the feature istangible or abstract. Map visualization of potential duplicates, with appropriate
background layers, aids in human evaluation. The database challenges for this processing
are significant, calling for custom data types, multiple (unlimited) attribution, andefficient geospatial processing. A proposed processing cycle is described.