664
October 2017
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
origins at Gusterberg, St. Stephan Tower (Vienna), Geller-
thegy, Pschow, and coordinates referring to Vienna Univer-
sity Datum, St. Anna Datum, and Hermannskogel Datum.
A new first-order net was started in 1936 and was completed
in 1956. The basic cadastral trigonometric net was connect-
ed with the first-or-der nets of Austria, Germany, Po-land,
and Romania (through the Carpatho-Ukraine and Slovakia).
Be-tween 1918 and 1932, the Military Geographic Institute
(MGI) applied the Lambert conformal conic projection for tri-
angulation computations and mapping. This was based on
the Hermannskogel Datum of 1871 referenced to the Bessel
1841 ellipsoid of revolution where the semi-major axis (a) =
6,377,397.155 meters and the reciprocal of flattening (
1
/
f
) =
299.1528128. The Hermannskogel 1871 Datum has its origin
with
f
o
= 48° 16´ 15.29˝ N,
l
o
= 33° 57´ 41.06˝ Est de I’lle de
Fer (East of Ferro Island in the Canaries), where Ferro = 17°
39´ 46.02˝ East of Greenwich and azimuth to station Hund-
sheimer is α
o
= 107° 31´ 41.7˝. The secant Lambert Grid had
the standard parallels of
f
N
= 50° 15´ N and
f
S
= 48° 30´ N, a
Central Meridian (
l
o
) = 35° 45´ East of Ferro, a False Easting
= 1,000 km, and a False Northing = 500 km. This point corre-
sponds to the center of the southern sheet line of the 1:75,000
sheet titled “4260 Vsetin.”
Professor Ing. Josef Krøvák (commonly spelled Křovák or
Krovak) prepared the Conformal Oblique Conic Projection of
Czechoslovakia in 1922 for the preparation of cadastral (tax)
maps and topographic maps of medium scales for the civil
geodetic service of Czechoslovakia. The “starting meridian”
was termed Ferro where the MGI usage differed from the ci-
vilian definition listed above. The MGI used the relation: Fer-
ro = 17° 39´ 45.90˝ East of Greenwich. The Krovak Projection
is a double projection in that the oblique conic is projected
from the Gaussian Sphere where the radius = 6,380,703.6105
meters. The Gaussian Sphere was “in-vented” by Carl Fried-
erich Gauss, and is also commonly known as the “conformal
sphere.” It is simply the geometric mean of the ellipsoidal
normal (at a point) terminated by the semi-minor axis and
the radius of the ellipsoid (at the same point) in the plane
of the meridian. To be succinct, it’s [υρ]
-1/2
evaluated in this
case at
f
= 49° 30´ N. For the Mapping Scientists and Photo-
grammetrists that do not live in South Louisiana, this is the
same formula used in the commonly used radius of the earth
for the “sea-level correction” in establishing ground control.
For the Czech Republic, they used the Bessel 1841 ellipsoid
at that latitude. Whenever one sees the term “double projec-
tion,” the generating sphere is usually the Gaussian Sphere.
The oblique cone has a pole centered at
f
= 59° 42´ 42.6969˝
N,
l
= 42° 30´ East of Ferro (southwest of Helsinki, Finland).
The spherical cartographic coordinates are trans-formed into
the rectangular plane coordinates of the uniform cadastral
system. For this purpose the reduced (0.9999) Gaussian
Sphere is projected on the surface of an oblique cone touching
the sphere around the central cartographic parallel, having
a cartographic latitude of 78° 30´ N, with the vertex in the
extended axis connecting the center of the sphere at the rota-
tion angle of 30° 17´ 17.3031˝. This is still in use as of 2000,
and is known as Systém—Jednotné Trigonometrické Sítì
Katastrální or S-JTSK (System of the Unified Czech/Slovak
Trigonometrical Cadastral Net). The Czechs state (Prof. Ing.
Bohuslav Veverka, DrSc., Prague, November 1997) that the
“scale, location and orientation of the S-JTSK on the surface
of the Bessel’s ellipsoid was derived from the results of the
historical Austro/Hungarian military surveys in the years
1862-98. There are 42 identical points on the Czech territory
used for transformation computations. Astronomical orien-
tation was measured only on the Hermannsko-gel trigono-
metrical point in Austria, scale factor was derived from the
basis of the geodetic length in Josefov.” Professor Veverka
published a program written in the Pas-cal language that
performs the direct and inverse transformations with the
Krovak Projection. Note that the X-axis normally coincides
with the meridian 42° 30´ East of Ferro increasing
South
,
and the orthogonal Y-axis is increasing
West
. A test point
provided lists:
f
= 48° 07´ 46.2973,
l
= 35° 42´ 35.2147˝, Y =
504,691.675 m, X = 1,289,068.724 m. The Krovak Projection
was officially adopted by the Czech military in 1932.
In 1939, the Germans found that during their occupation
of the “Protectorate of Bohemia and Moravia,” only 5% of the
Protectorate’s territory was covered by the new topo-graphic
survey. The Landesvermes-sungsamt Böhmen und Mähren
(Land Survey of Bohemia and Moravia) was formed. The
subsequent triangulation was incorporated into the final Re-
ichsdreieck-snetz (Triangulation Net of the Empire), with the
datum origin being at Pottsdam where Φ
o
= 52° 22´ 53.9540˝
North, Λ
o
= 13° 04´ 01.1527˝ East of Greenwich. The de-
fining azimuth to station Golmberg is: α
o
= 154° 47´ 32.19˝,
and the ellipsoid of reference is the Bessel 1841. For the pur-
pose of incorporation, the Reichsdreiecksnetz was ex-tend-
ed over the territory of the Protectorate, and 36 first-order
stations were re-observed with two new base lines measured
at Podébradý and Kroměřiž. The Grid system used was the
Deutsche Herres Gitter (DHG) which had the exact same pa-
rameters of the UTM Grid except that the scale factor at or-
igin was unity. The DHG is exactly the same as the USSR’s
Grid (Russia Belts) except for the ellipsoid.
After WWII, the agencies responsible for geodetic, topo-
graphic and cartographic activities in the Second Czechoslo-
vakian Republic were in a stage of re-organization up to the
end of 1953. During the years 1953-54, those agencies were
subsequently organized according to the pattern established
in the USSR. The Ustřední Správa Geodesie a Kartografie
– USGK, (Central Ad-ministration of Geodesy and Cartog-
raphy) was established. The Zakladni Trigonometrickasit –
ZTS (Basic Trigonometric Net), included the first-order net of
the Protectorate and the first-order net established in 1949-
1955 in Slovakia. The adjustment of the net was carried out
by the method of Pranis-Praniévitch on the Krassovsky 1940
ellipsoid where a = 6,378, 245 meters, and
1
/
f
= 298.3. The
Datum is defined as “System 42” where the origin is at Pulko-
vo Observatory: Φ
o
= 59° 46´ 18.55˝ North, Λ
o
= 30° 19´ 42.09˝
