3. STATUS OF THE GEODETIC SURVEY
3.1 Control networks
Unified National Horizontal Network (EOVA)
- 22 sites of the National GPS Network (OGPSH) have been completely measured and both in HD72 and three dimensional,
- 139 sites of 1st order (completed),
- 2120 sites of 3rd order (completed),
- 4790 sites of principal 4th order together with 10306 -orientation sites (completed),
- 44000 sites of 4th order (completed).
The EOVA datum is the Hungarian Datum 1972 (HD72), the network orientation is provided
by 40 Laplace-points and the scale is maintained by 6 baseline and 17 EDM lines.
Parameters of connection of the Hungarian control network to the EUREF system have been
computed and finalized.
Unified National Vertical Network (EOMA)
- 41 principal fundamental benchmarks (completed),
- 5778 sites of 1st order (completed),
- 2670 sites of 2nd order (ready at 50%),
- 5521 sites of 3rd order (ready at 50%),
- a vertical network consisting of 20000 benchmarks with earlier determination also exists.
The reference system was classified for decades in Hungary, even the information on the projection system was
not available for users outside of Hungary. To meet the requirements of the domestic and international
professional community, these pieces of information were released for public use in the last four years. Recently,
based on earlier results achieved in IAG and CERCO WG VIII, a Description Directory of Hungarian Reference
and Projection Systems (4th revised Edition) June 1995 has been issued by FÖMI. The paper gives an overview
on the EOV (Unified National Projection) parameters, the HD72, the Hungarian altitude system and the relation of
HD-72 to the WGS-72 and EUREF-89 (WGS-84) systems.
This Directory allows the user (e.g. the MEGRIN Data Service Centre) to perform per point coordinate
transformation between the systems mentioned (EOV to EUREF-89 and WGS and vica versa). This capability
provides a wide range of interdisciplinary utilisation in geo-referencing, spatial data handling and GIS applications
even in regional and continental level. (To obtain a copy of the document in Hungarian or English please write
Dr. Sz. MIHÁLY, Scientific vice director, FÖMI, Sas u.19, 1051 Budapest Hungary). The Description Directory is
aimed to be introduced as Hungarian Standard. A centralized Geodetic Point Database of horizontal, vertical and
3D networks of Hungary has been elaborated and introduced by FÖMI. Loading the data into the database has
already been started and is expected to be finished next year.
Some of the recent and anticipated follow-on activities are:
- Finishing the vertical network using GPS technology and spirit levelling
- Some minor actions to connect the Hungarian geodetic fundamentals to EUREF and UELN
- Densification of the National Zero-Order GPS Network in order to obtain the 1000-site National GPS Network
- National GPS Observation Service for use in different applications
- Maintaining and analysing the Hungarian GPS Deformation Network
- Participating the International GPS Geodynamic Service
- Adapting GPS technologies for application in different survey tasks.
Upon the call of IAG/EUREF subcommission of 1994 Hungary has prepared data expressed in geopotential index
numbers for the purpose of connecting the Hungarian vertical network to the UELN frame. The Hungarian
IAG/EUREF contact person, Dr. József Ádám handed over the data to Prof. Augath on the Subcommission's
Technical Working Group meeting on 15-16 December, 1994 in Germany.
Talks have been held with Croatian and Slovenian colleagues on works of connecting the neighbouring national
vertical frames.
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