Internc
STRATEGIES FOR UPDATING A NATIONAL 3-D TOPOGRAPHIC DATABASE
AND RELATED GEOINFORMATION
P. Frederiksen, J. Grum, L.T. Joergensen
National Survey and Cadastre — Denmark, Rentemestervej 8, DK-2400 Copenhagen NV, Denmark
(pof, jrg, Itj)ukms.dk
Inter-Commission WG II/IV
KEY WORDS: Photogrammetry, Topographic Databases, Revision, Production, Infrastructure, DEM/DTM
ABSTRACT:
A national topographic database for Denmark was established during the 1990'ies and completed at the end of year 2000. The
database comprises three components: A 3-D vector database with full topology, a database with names of places and points of
interest and an elevation database.
This paper is about the revision and maintenance of the databases.
The vector geometry was captured photogrammetrically. The update takes place in a 5 years cycle, i.e. 2096 of the country is revised
every year according to detailed specifications. Due to user needs focus is now on administrative revision in order to update specific
object types with a higher frequency than 5 years. Roads, road names, hydrographical networks and building are of special interest TOPIO
for the geo-data infrastructure. frequen
The origin of the database for place names and points of interest goes back to the 1970'ies. It is maintained by an extensive use of
sources in the public and private sectors utilising the Internet. It's a dynamic process where new sources are identified frequently In gene
and agreements concluded with the data providers. all thre
The third database component, the elevation model, is based on digitised contours and heights from selected objects from the 3-D accurac
vector database. Spot heights, i.e. maximum and minimum elevation points, measured in connection with the photogrammetric a data n
revision of vector data are also included. Heights in the elevation model are estimated by a data fusion approach considering on both
| characteristics of the individual data points. Data is stored in a grid structure and as computed contours.
i The ge
| 1:25.00:
| years, 1.
| 1. INTRODUCTION 2. CONCEPT OF THE TOPOGRAPHICAL DATABASES
i When |
The topographical mapping in Denmark (scale 1:10.000 and The objective was to establish one single topographical defined
smaller) is the responsibility of the National Survey and database where data should be collected only once, stored and
Cadastre (KMS) - an institution under the Ministry of the updated. Data redundancies should be avoided as much as
Environment. possible. From this database all other application databases
should be derived.
In 1995 the TOPIODK topographical database was defined. The
abbreviation TOPIODK is the synonym of the topographical The derived databases are defined from the degree of details in
database with the reference scale 1:10.000 in Denmark. The the data rather than a specific scale factor. The degree of details
geometrical part was established during the late nineties by implies
photogrammetry. e À list of objects in each derived database
e Corresponding generalisation specification.
Since then the TOPIODK has developed into a concept e Scale interval for proper use of data
comprising a number of more or less integrated databases.
The more important databases are: From the derived databases thematic maps, data for GIS
e The database holding geometry of objects purposes, printed maps or data specifically meant for screen
* The database for place names and points of interest maps in Internet services are extracted.
(POI) :
e The elevation database It is crucial that all updates are stored in the TOPIODK
databases, i.e. geometry, heights as well as POI and names.
Conceptually, TOPIODK also holds a separate road network
database.
3. GEOMETRY
The TOPIODK was completed covering the entire country at
the end of year 2000. Since then the task has been to develop 3.1 Geometry Characteristics
and implement a revision strategy.
The geometry part of the database includes 51 object types
subdivided into 8 object classes - ail described in details in the
604
