PE&RS June 2015 - page 437

PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING June 2015 437
Republic (704 km) (PE&RS, January 2000), Denmark (140
km) (PE&RS, November 2006), France (418 km) (PE&RS,
January 2001), Luxembourg (128 km) (PE&RS, November
2005), Netherlands (575 km) (PE&RS, February 2003),
Poland (467 km) (PE&RS, September 2000), and Switzerland
(348 km) (PE&RS, August 2001). The terrain has lowlands
in the north, uplands in the center, and Bavarian Alps in
the south. The lowest point in Germany is Neuwndorf bei
Wilster (-3.54 m), and the highest point is Zugspitze (2,963
m) (WorldFactbook, 2015).
The following is taken verbatim from The Western
European Datums by Jacob A. Wolkeau of Army Map
Service, (unpublished manuscript, circa 1950). “The
survey and mapping position of pre-war Germany presented
even greater complexities than were to be found in
France. Practically each German State had its own Survey
Department with its own triangulation and mapping system.
The triangulations were based on different origins computed
on different figures of the earth, and, in general, unconnected
across the frontiers of the States. The maps were reproduced
on a variety of projections and with no common system of
symbols or methods of showing relief, and moreover, at the
frontiers, sheets did not include detail in adjoining States.
The absence of control by one central survey and mapping
authority was further emphasized by the lack of uniformity
in the precision of the various State triangulations and
the varied rates of progress in map reproduction and map
revision.
“The triangulation of the former Prußischen
Landesaufnahme (Prussian Land Survey – Ed.) , extending
over the whole of Prussia and almost all the small North
German States, and the separate triangulations in
Mecklenberg, Saxony, Bavaria, Wurtemberg, Hessen and
Baden, dates from the first half of last century (19th century
– Ed.). The history of the Prussian measures is contained
in twenty-four volumes entitled Abrisse Koordinaten und
Hohen, which give all the information necessary for a
practical trigonometrical knowledge of Prussia and the
Rhine Provinces.
“The particulars of the other States of the German
Confederation are not generally available but they are
probably now only of historical interest, in view of proposals
which have been made for the coordination of all German
surveys.
“In 1921 a special Survey Committee was appointed
to draw up plans for the improvement of the survey and
mapping position, and in 1923 this Committee made various
recommendations to secure a unified triangulation net
and a single coordinate system for the topographical maps
of the Reich. The complete union and adjustment of the
triangulations of the various States into a single network free
of distortion and residual errors desirable as it may be from
a scientific point of view, was realized to be impracticable,
as it would imply a complete re-computation of most of the
nets, a project which was financially impossible. The Survey
Departments of the various States, which were still to be
maintained as separate entities, were therefore enjoined to
employ a simplified solution of the problem, in which only the
specially disturbing errors of the older parts of the network
were to be eradicated and the bulk of the existing network
preserved intact. In this process the chains and networks
of the Prußischen Landesaufnahme lying West of the 13th
Meridian, and the West and east Prussian networks were to
be left undisturbed and joined by the modern chain between
Berlin and Schubin bases, which was to be freshly adjusted.
The remainder of the triangulations of the Reich were to be
joined to the above system and the Prussian Geographical
Coordinate system and datum adopted for the whole of the
Reich.
“The origin of the national survey of Prussia completed
in 1859 was the old Observatory at Enckeplatz, Berlin. The
accepted values for the latitude and longitude were: Φo = 52°
30′ 16.68′′ N, Λo = 13° 23′ 55.23′′ (East of Greenwich). The
longitudes of the Prussian Survey were referred to the
Island of Ferro in the Canaries and the Meridian of Ferro
was conventionally fixed as 20° West of Paris. The new
fundamental azimuth obtained from the adjustment of the
Berlin-Schubin chains the line Potsdam-Golmberg, whose
value is αo = 154° 47′ 32.41′′. The Bessel Spheroid used by
the Prußischen Landesaufnahme is adopted for the proposed
unified triangulation system. The data of this spheroid,
which fits the Geoid particularly well in Mid Europe are: a
= 6,377,397.15500 metres, b = 6,356,078.96325 metres, f =
1/299.1528128.
“At the end of the Great War no less than about fifty
rectangular co-ordinate systems were in general use
throughout Germany. For the purpose of the standardization
of the topographical maps, the Committee therefore
recommended the adoption of a single co-ordinate system
for the whole of Germany plotted on the Gauss transverse
conformal projection directly from the spheroid on to the
plane by Kruger’s formulae (Gauss-Krüger Transverse
Mercator – Ed.) .
“By the circular of the 31 st May, 1935, the uniform
production, printing and publishing of the following maps
for the whole territory of the Reich is centralized in the
Reich Survey office. The uniform production of the 1/50,000
map is an innovation and as a temporary measure some of
the sheets of the 1/100,000 of Bavaria and Wurtembureg will
still be produced by local authorities on behalf of the Reich
Survey Office” (Wolkeau, ibid.).
This system was known as the DHG or Deutches Herres
Gitter (German Army Grid) and has identical specifications
for the U.S. Army’s UTM with just a few differences. The
DHG was referenced only to the Bessel 1841 ellipsoid,
the scale factor at origin is unity (1.0) and each 6° zone is
numbered Eastward from Greenwich, England, and the 500
Km False Easting is preceded by the zone number in the
millions unit place.