The name of the place: towards a model for interconnection of geographical entities

The name of the place : towards a model for
interconnection of geographical entities

Øyvind
Eide
The Museum Project,
University of Oslo
oyvind.eide@muspro.uio.no

Lars-Jørgen
Tvedt
The Documentation Project,
University of Oslo
l.j.tvedt@muspro.uio.no

Jon
Holmen
The Museum Project,
University of Oslo
jon.holmen@muspro.uio.no

2002

University of Tübingen

Tübingen

ALLC/ACH 2002

editor

Harald
Fuchs

encoder

Sara
A.
Schmidt

Introduction
The Documentation Project and the Museum Project are cooperative projects
between the four universities in Norway. Since 1991, these projects have
performed retro-conversion and digitization of analogue archives, books,
images and other media types. During the building up of our diverse
collections, the need for a model expressing relationships between place
names has been strongly felt, both in the modelling and the presentation of
each collection and in the present work towards deeper integration between
the various collections.
In our paper, we will present an object-oriented model for expressing
relations between geographical objects applied on Norwegian geographical
information taken from our digital collections, followed by a discussion
about further development and implementation of the model.

Previous efforts
In connection with geographical reference systems for digital libraries we
commonly find the use of UTM coordinates in the specification of
geographical entities, as seen e.g. in the Alexandria project (Beard 1997).
Whereas this method gives many possibilities both for use in single
collections and in the interconnection of heterogeneous collections of
information object, this method is not suitable for collections that
contains a large number of references to geographical entities for which it
is impossible or unfeasible to enter this type of coordinates.
Whereas the use of UTM coordinates will be an important part of our system,
we have to design a system which does not depend on this type of
information. As the basic structure in the organization of the geographical
information objects, we use the political geography of Norway. At any single
point in history, this structure takes the form of a tree, as seen in fig.
1. However, this tree structured model is too restricted to cover
collections spanning a time period. It have to be expanded, as we will see
below.

Vegard Elvestrand has published a standard for geographical classification
(Elvestrand 1977) with municipalities as the smallest unit. The number of
municipalities in Norway has changed a great deal through splits and
unifications. His model is effective for the classification of literature;
one of our collections is classified according to his standard (Eide, 1998
p. 287-288), but the underlying model is also too restricted for our use.
His model contains classification symbols for every municipality that has
existed, but it has no linking showing the actual changes.
Norsk samfunnsvitenskapelig datatjeneste
(Norwegian Social Science Data Services, NSD) has designed various databases
based on the administrative structure of Norway, directed towards the needs
of the social sciences to present data on present and historical statistics
(NSD 1997, chapter 3). Their model is effective for historical models of
municipalities, but it does not allow us to include the multiple systems of
geographical information needed for cultural and natural historical
information systems, as we will see below.
The model described here is conform with the CIDOC object-oriented Conceptual
Reference Model (CIDOC 1999), and we will follow the further development of
the CIDOC model closely as we develop and implement our model of
geographical information.

Places vs. place names
There are several other structures interconnected with the simple structure
of fig. 1, e.g.:
Other administrative regions, e.g. police districts, clerical
districts
Named geographical formations, e.g. lakes, mountains,
rivers
Property structures, e.g. farms, common land

In the geographical model in fig. 1, there is no distinction between a place
and a place name. The difference between a geographical unity in the real
world and the name we use to refer to this unity must be expressed in any
geographical model. There are two main reasons for this:
The same word often refer to several distinct places. One example
of this is a municipality called Våler, which is found in the county
of Hedmark as well as in the county of Østfold.
Political structures may change. The area of the town of Hamar is
larger today than it was ten years ago, whereas the municipality of
Vang no longer exists (in a bureaucratic sense of the word exist),
as it is included in the expanded town of Hamar.

In fig. 2, our basic geographic model is
sketched, populated with several geographical objects. The idea behind the
model is not to represent all potential information about geographical
entities and their relations, but to include enough information to perform
computer search, browse and interconnection between objects in an effective
way.

Each object in our model may have an attribute showing the time span that the
geographical entity was known in that form. This does not mean that the
object is placed in a time continuum, as it has a distinct, everlasting
geographical location, which may be expressed in geographical coordinates.
The time span is just an attribute showing which time period this specific
geographical object was referred to. This is especially important for legal
entities such as municipalities. Municipalities described as old or new in the
figure have been split up or united.
The direction of the graph is always from the bigger unit to the smaller
unit: a unit pointed to is a part of the unit pointing from. To make this
possible, we have split geographical entities covering parts of several
other entities into parts shown on the figure as hp for hill parts and sp for sea
parts. Each such part is part of both the sea as a whole and the
municipality that this part is located in.
The known place object contains a name, an optional time span, and references
to other objects forming the graph. As some of our collections contain UTM
data, and as we will be able to import such data for all our municipalities
from e.g. NSD, the object also contains an optional UTM attribute.

Expansion into the unknown
We define each actual mentioning of names in texts and other media as an
observation. In this context, observations are all references to
geographical entities in information objects. Their relation to the model is
seen in fig. 3. These observations are external
to the model; whereas the model shows the objective reality (in the meaning
agreed upon, checked), observations are subjective references made by a
human being at a specific time, although this time may be uncertain or
unknown.

An observation will never refer to more than one place-name by definition. If
there is more than one link from an observation to known facts, such a split
expresses an insecure fact, in which case an observation may relate to one
out of several possible known places, but we do not know which one.
There is no limitations as to what kind of entities may be included in an
implementation of this model, but we will have to decide on standards when
we use the model in actual work. The development of such standards will be
be discussed in our paper, together with search facilities and matters of
implementation.

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