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FURTHER DEVELOPMENT OF THE HUNGARIAN DTM AND LAND COVER TELECOMMUNICATION DATABASE
Dr. Ákos DETREKÓI, Dr. Gábor MÉLYKÜTI, Gyórgy SZABÓ
Department of Photogrammetry, Technical University of Budapest, Hungary
Commission IV, Working Group 4
KEY WORDS: Geomatics, Land_Use, Updating, Database, DEM/DTM, Quality
ABSTRACT:
The increasing importance of complex telecommunication systems take into focus the efficient spectrum management
techniques. In the past the conventional radio and broadcast systems have been planed based on empirical wave
propagation models. The limited radio frequency spectrum and upcoming digital services set considerably higher
requirements in wave propagation models.
In the period from 1990 until 1993 the Hungarian Digital Terrain Model (DTM-50) and Land Cover Database was
realized.
The paper discussed the possibilities of revision, updating and quality control of the database in a complex digital
photogrammetric environment.
1. Historical background
At the end of the last decade based on the available data
sources and relatively poor east-European technical
background a robust technology was developed to stand
up the Hungarian Digital Terrain Model (DTM-50) and
Land Cover Database. The key words was the following:
time effectiveness, limited cost, limited technical
background, limited technical expertise, robust
technology, homogenous global accuracy.
In the period from 1990 until 1993 the Hungarian Digital
Terrain Model (DTM-50) and Land Cover Database was
realized. The Frequency Management Institute of Hungary
(FGI) cooperation with the Military Mapping Agency
(MHTATI), Department of Photogrammetry TU Budapest
and Geomatik Ltd. realized the integrated GIS based DTM
and Land Cover Database of Hungary.
After the initial data capturing the next step was the
integration of the digital database to the different
application systems.
The technology "GIS" gives an unique possibility to solve
complex tasks. In the telecommunication the GIS
systems managed the land surface dates and the
different technical dates connected to it in solving wave
propagation problems of government tasks and
engineering planning. Land surface data types can be
modeled by complex structures. The tasks of
telecommunication need the reflection properties of the
surface besides the height data of the land. The reflection
properties of surface is determined by the land covering.
The height and covering of the surface give enough
information together to solve the telecommunication
tasks. An user environment to solving government
controlling or planning tasks can build up on an
information system, which is using these data together.
Up to now the following areas applied the DTM and Land
Cover Database:
- Government frequency management
- Point-point microwave planing
- Microwave broadcasting
- Radar planing optimization
- Flying object visibility simulation
219
1.1. The countrywide DTM-50 database.
One main element of the information system is the
countrywide elevation database of Hungary, DTM-50*50
m^. it is a raster structuring database, of density 50 and
contains about 40 million grid points. The grid net is
parallel with the axes of Unified National Mapping System
(EOTR). The DTM-50 system was derived from 1:50.000
scale topographical maps. MHTATI made the data
collection, using scanner techniques. The height values
was derived from the digitized contour lines, computing in
the intersection points of the grid net. The derived height
values were filling into the database across more
controlling phase. The requirements of accuracy were
changing by the character of land surface. The
topographical map sheets were classified into categories,
based on the represented relief.
1.2. The Land cover Database
The natural and artificial terrain object's height and
character determine the reflection of land surface. In this
project 14 different covering type were determined. There
were point, line and surface type elements among them.
The determination of the different elements were made by
topographical maps, aerophotos and field control.
The different covering types: singular object (chimney,
antenna, tower, ect), river, road, electrical aerial line,
bridges, meadow, low vegetation, water surface, low-
medium-high vegetation, low-medium-high buildings.
The covering information stored in two different database
structure. One is the vector and the other is raster. The
vector covering database is include the point and line
elements coded with symbol key, according to their
position on the map, area elements with their borderlines.
The raster covering database - in keeping with the
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996
