16
January 2017
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
Gellérthegy. (The observatory was torn down and replaced
by a stone fortress on Gellért hill. The old point was then
later found to be on the rampart of that fortress, and a
National Report to the IUGG portrayed a photograph of
the point marked by a gazebolike canopy!) The origin of the
coordinate system was defined where: Latitude of Origin (
f
o
)
= 47° 29´ 09.6380˝ North, with a Central Meridian (
l
o
) =
36° 42´ 53.5733˝ East of Ferro (Ferro = 17° 39´ 46.02˝ West
of Greenwich as derived from astronomic observations
in 1907). The defining azimuth was from Gellérthegy to
Nagyszal where: α
o
= 191° 28´ 52.19˝ as retained from the
1874 datum values from Vienna University. The ellipsoid of
reference was the Bessel 1841 where: the semi-major axis (a)
= 6,377,397.155 meters and the reciprocal of flattening (
1
/
f
)
= 299.1528128. The False Easting and False Northing were
each 500 km.
The northern part of Transylvania, occupied by the
Hungarian Army inWWII, was mapped with a system defined
as the “Marosvásárhely Stereographic System” with a Datum
Origin point at the cadastral triangulation station Kesztej
where: Latitude of Origin (
f
o
) = 46° 33´ 09.12˝ North, and
with a Central Meridian (
l
o
) = 42° 03´ 20.955˝ East of Ferro.
The defining azimuth from Kesztej to Tiglamor was: α
o
= 146°
57´ 41.052˝. The False Easting and False Northing were each
600 km, and this local Datum and Grid was referenced on the
Bessel 1841 ellipsoid.
The Hungarian surveying and mapping agencies went
through a series of reorganizations after WWII through 1952-
54 when the country began to follow the pattern established
by the USSR. The Gauss-Krüger Transverse Mercator
projection was adopted in 1957 with the Grid parameters of a
scale factor at origin equal to unity, and false origin 500 km
West and 5000 km North. Since 1954, the Krassovsky 1940
ellipsoid was used where: the semi-major axis (a) = 6,378,245
meters and the reciprocal of flattening (
1
/
f
) = 298.3. Prior
to 1957, the Central Meridians (
l
o
) for military mapping
were 18° and 21°, and after 1957, 15° and 21° were used.
For cadastral mapping since 1957, the Central Meridians
of 17°, 19°, 21°, and 23° were used. The Hungarian Datum
of 1957 with origin coordinates at Erdóhegy and associated
parameters were kept secret for military purposes.
The new national Hungarian Datum of 1972 (HD 72), also
known as the “Unified National Horizontal Network of 1972”
(EOVA Datum of 1972), is defined with origin coordinates at
Sztlthegy where: Φ
o
= 47° 17´ 30.44˝ North, Λ
o
= 19° 36´ 10.18˝
East of Greenwich. The defining azimuth is from Sztlthegy to
Erdthegy: α
o
= 209° 55´ 27.79˝. The corresponding geodetic
parameters of this origin are:
f
o
= 47° 17´ 32.6156˝ North,
l
o
= 19° 36´ 09.9865˝ E. The defining geodetic azimuth is: α
o
=
209° 55´ 26.64˝ and the ellipsoid of reference is the Geodetic
Reference System (GRS) 1980. For the origin, h
o
= ellipsoid
height, H
o
= height above the Baltic Sea and N
o
= geoid
undulation. Therefore, h
o
= 235.80 meters = H
o
+ N
o
= 229.24
m. + 6.56 m. The published transformation parameters from
HD-72 to WGS 84 are:
Δ
X = –5.3 m,
Δ
Y = +157.77 m,
Δ
Z =
+31.6 m, k = –2.11 ppm, R
z
= –1.11”, R
y
= –0.50”, R
x
= –0.97”.
Remember the Hungarian transverse cylindrical Grids of
1908 mentioned several paragraphs ago? Well, the new
system is based on a new definition of that old Hungarian
favorite.
The Egységes Orzágos Vethleti rendszer (Uniform
National Projection system) “EOV Grid” is a conformal
double transverse cylindrical projection. The Grid is defined
at:
f
o
= 47° 08´ 39.8174˝ North, Central Meridian,
l
o
= 91°
02´ 54.8584˝ E. The false origin is 200 km east (+X), 650 km
north (+Y), and the scale factor is = 0.99993. The national
fundamental benchmark is at Nadap where H = +173.1638
meters above the Baltic Sea and H = +173.8388 meters above
the Adriatic Sea.
U
pdate
The Institute of Geodesy Cartography and Remote Sensing
(FÖMI) according to the Hungarian Government’s Decree No.
1312/2016 (13 June) by legal succession – with integration
into the Government Office for the Capital, Budapest – will
be dissolved. FÖMI will continue its professional activities
within the organization framework of the Government Office
for the Capital, Budapest from 1st January 2017.
The GNSS reference system is the 3-dimensional geocen-
tric Cartesian system ETRS89 (realised in Hungary by the
OGPSH). For practical surveying and mapping works, the lo-
cal HG72 system has to be used. The transformation between
the two independent systems is possible based on common
points. The accuracy of the transformation cannot exceed the
accuracy of the geodetic networks (or sub-networks). There
are therefore many possible transformations within the lim-
its. However, it is reasonable to apply the transformation in
a standardised way. To this end, the EHT software was de-
veloped and released by the FÖMI SGO in 2002. Its method
is based on a local transformation using OGPSH points and
provides the best available accuracy. The program automat-
ically selects the suitable nearby reference points from its
data base. It works for the whole territory of the country. The
new version released in 2008 is already capable of transform-
ing the coordinates in both directions. The EHT is available
free of charge from the
web site.
INSTITUTE OF GEODESY, CARTOGRAPHY & RE-
MOTE SENSING, 2016
The contents of this column reflect the views of the author, who is
responsible for the facts and accuracy of the data presented herein.
The contents do not necessarily reflect the official views or policies of
the American Society for Photogrammetry and Remote Sensing and/
or the Louisiana State University Center for GeoInformatics (C
4
G).
This column was previously published in
PE&RS
.
