PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
October 2016
761
by
Clifford J. Mugnier, CP, CMS, FASPRS
T
his month’s topic features the Kingdom
of Belgium, the birthplace of Mercator,
which gained its independence from the
Netherlands in 1830. Famous Belgian place
names have become prominent in many battles,
including Waterloo and part of the Battle of
the Bulge. Triangulation was originally carried
out by Snellius (1617), Cassini (1745-48),
and General Krayenhoff (1802-11). Although
largescale topographic coverage dates back
to 1744, the organized national mapping was
carried out by the military “Depot de la Guerre,”
originally founded in 1831. This national mapping
organization has gone through a number of name
changes until becoming a civilian agency in 1976
with the present name of “Institut Geographique
National de Belgique” (IGNB).
The classical first-order triangulation of Belgium was
carried out between the years 1851 and 1873, when 84
primary stations were established. The Observatoire
Royale d’Uccle Datum of 1884 was based on the origin of
the old Brussels Observatory: Φ
o
= 51
o
10´ 06.895˝ North,
Λ
o
= 04
o
22´ 05.89 West of Greenwich, and the ellipsoid of
reference was the “Carte de France” (Delambre 1810). The
triangulation was dependent on two measured bases at
Lommel and Ostend with Beverloo as a base of verification.
The ellipsoidal Belgian Bonne Grid was used with this
datum from 1884 to 1919 with no False Easting or False
Northing, and was later referred to as the “Old Convention”
Grid. The lack of a false origin is typical for late 19th century
grid systems, and is a common theme found in European
and colonial grids of that era. Negative grid coordinates
(in the appropriate quadrants) were accepted as a normal
THE KINGDOM OF
The Grids & Datums column has completed an exploration of
every country on the Earth. For those who did not get to enjoy this
world tour the first time,
PE&RS
is reprinting prior articles from
the column. This month’s article on the Kingdom of Belgium
was
originally printed in 1998 but contains updates to their coordinate
system since then.
way of doing things. Note that the Bonne projection is an
authalic (equal-area) projection. Many countries in Europe
followed the French preference for the Bonne, in spite
of the fact that it is a miserable projection for large-scale
military and civilian engineering applications. The Bonne
projection tables were easy to compute on the ellipsoid. That
advantage apparently helped to keep it popular, in addition
to the prestige afforded by adopting the same system as
used by the French.
After the “Great War” (WWI), the Kingdom modified
the Grid such that the False Easting = 150 km and the
False Northing = 120 km. The “New Convention” Bonne
Grid (1919-1950) had a Latitude of Origin (
f
o
) = 50
o
24´
North, and a Central Meridian (
l
o
) = 4
o
22´ 05.91˝ West of
Greenwich. In postwar years, the Belgians continued to re-
observe and re-adjust their triangulation network. In 1924,
Photogrammetric Engineering & Remote Sensing
Vol. 82, No. 10, October 2016, pp. 761–763.
0099-1112/16/761–763
© 2016 American Society for Photogrammetry
and Remote Sensing
doi: 10.14358/PERS.82.10.761
