TOP10DK, THE NATIONAL TOPOGRAPHIC DATABASE OF DENMARK
Lars Tyge Jorgensen, National Survey and Cadastre - DENMARK
Commision IV, Working Group IV/1
KEY WORDS:
Photogrammetry, Mapping, Specification, Database, GIS, Production.
ABSTRACT:
In 1994 The National Survey and Cadastre - Denmark began the establishment of a digital topographic database. The name of the
database is TOP10DK indication that the database is intended for TOPographical mapping in the scale of 1:10.000 (and smaller) in
DenmarK. The purpose of the database is to serve as a background for intelligent GIS where the users install their own keys and for
production of plain, cartographic products without any human Interference. On the first hand, effort is concentrated to establish the
database nationwide. This is due to user wishes, stating, that coverage was more important than content. Therefore the first version of
the database is reduced in number of object types, but not in geometry. On a long term basis, the database will form the basis of map
production for medium and small scale topographic maps in Denmark. The database will be established using EU tendering leaving less
than 10% of the work for in-house production. Except for_test areas no areas have been completed but production is taking place in
approximately 30% of the contry and total coveridge is expected to be reached in year 2001.
1. BACKGROUND
The National Survey and Cadastre - Denmark is responsible for
the geodetic networks of Denmark, Greenland and the Faroe
Islands, the topographic mapping of these areas, the nautical
charts covering the waters surrounding these areas, and the
cadastral service in Denmark.
The National Survey considers it as one of its prime tasks to
provide modern and up to date maps and map data to the Danish
society. Therefore, the National Survey has decided to rearrange
the production of topographical maps in Denmark. The production
methods are now almost reorganized to digital manners and it has
been decided to produce a modern topographical database. This
database will be suitable for modern GIS and on long terms form
the basis of holding the updating of all scales of topographical
map series in Denmark.
This database, named TOP10DK should reach an accuracy of one
metre for well-defined points and have an updating frequency of
five years. On the long term updating data should be bought from
the municipalities, which produces the digital technical maps in
Denmark. The number of municipalities is 275 and it is doubtful
wether they all can handle this task in near future. Therefore the
National Survey will carry out the updating until the municipali-
ties are cable of carrying out the updating of maps in Denmark.
2. PRECONDITIONS
In the beginning of the 1980 the utility companies forced the
private photogrammetic companies to introduce digital methods
in the production of technical maps in Denmark. During the
eighties most of the urban areas in Denmark except big cities were
digitally mapped. During this process standards for technical maps
and for data exchange were developed. In the same period the
National Survey went on plotting analog manuscripts for the
production of the base map of Denmark scale 1:25.000. The
production of this map was the third mapping of Denmark and
was planned to end in the beginning of the nineties. In 1988 the
major utility companies asked the National Survey to participate
in a digital small scale mapping of all rural areas of Denmark,
because they needed an overview map to put behind the registra-
tion of their utility networks. A major problem was disagreement
concerning copyright. Another problem was that utility companies
owned much digital map data covering small areas, and these
areas were to be included in the mapping. Since the urban area
maps were large scale maps produced using different standards,
problems arose concerning homogeneity. The National Survey
had no money for such a project and the utility companies
continued, without the participation of the National Survey, to
define and produce the map. The map was to be produced from
aerial photographs scale 1:25.000-1:30.000, and no areas were
defined except buildings, and topology was not considered. The
consequence was, that in four years starting in 1989 all rural areas
of Denmark were digitally mapped using standards, which were
not designed for future use. The National Survey succeeded to
cooperate with some utility owners and participated in one project
covering app. as third of the area of Denmark.
3. STANDARDS
During the eighties several standards for technical maps devel-
oped in Denmark. The development took place rather uncoordi-
nated but after a while some standard were developed. In 1988
this standard for technical maps was redesigned describing three
levels of maps, from the most detailed maps to overview maps in
scale 1:10.000. The mapping of the rural areas caused a new
standard in 1989, which did not fit into the hierarchy of the other
types of maps. A working group was created to write a new
standard and solve the problem of hierarchy. The intention was
that the National Survey would end its own collection of data for
updating databases and analog map production. Instead updating
should be based on data collected for updating large scale
technical maps. Unfortunately we did not succeed in incorporating
all the wishes of the National Survey in the new standard, but
many problems were solved. Besides the hierarchic extensions,
which were incorporated to make it easier to build up topology, it
was stated that all map data should be 3D data.
In the same period the standard for data exchange was also revised
and updated to meet new defined context in data.
390
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996
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