background image
he collection of the aerial photo-
graphs of the NGI contains about
80,000 greyscale images of Belgium, start-
ing after the Second World War.These
images were used for the photogrammetric
extraction of all necessary information
needed by cartographers to make detailed
maps. As topographic reconstruction of the
altitude of the surface requires a stereo-
graphic view of the landscape, these aerial
photographs were taken in strips with at
least 60% overlap in the flight direction
and at least 15% overlap between adjacent
strips.These historical aerial images are
useful for private as well as professional
purposes ranging from visual to pho-
togrammetric usage.The oldest aerial pho-
tographs are on glass plates of 18 cm x 18
cm; later, polyester film rolls with images
of 23 cm x 23 cm were used but cut into
single photographic sheets for further use.
The KMMA's collection contains 300,000
aerial photographs on glass plates (partly
only in the form of paper contact copies)
taken by the NGI in the Congo, Rwanda
and Burundi after World War II until the
end of the colonial occupation in 1960.
These images are often the only source of
visual information available for ecological
studies concerning erosion, human occu-
pation, and vegetation .The first aerial
photographs were taken on glass plates. A
special machine was designed that made it
possible to exchange the glass plates in the
aerial camera automatically during the
flight. Later, 24-cm film rolls were used. and
in the astrophotographic
plate archive of the Royal
Observatory of Belgium
(KSB, http://www.astro. In collaboration
with the astronomical insti-
tutes of the Vrije Univer-
siteit Brussel (VUB) and the
Universiteit Antwerpen
(UA) and AGFA-Gevaert, a
world-leader in photograph-
ic matters, the goal is to
acquire the necessary know-
how, hardware and software to digitise the
information contained in the photographic
plates, as well as the associated metadata.
The project set out to offer the results to
the public and to make them directly
usable for scientific research through the
modern techniques of the information
roject Co-ordinator
and Project
Scientist Jean-Pierre
De Cuyper,
of the
Royal Observatory in
Belgium, spoke to
DigiCULT about the
digitisation of astronomi-
cal and aerial photograph-
ic plates and the unique
technical challenges posed
by this new archiving
he aim of this pilot project, financed
by the Belgian Federal Public
Planning Service Science Policy
(, is to preserve the
historic-scientific information contained in
the aerial photographic archives of the
National Geographical Institute (NGI, and the Royal
Museum of Central Africa (KMMA,
"Old photographic plates contain valuable
information about the position and the bright-
ness of heavenly objects that cannot be repro-
duced by modern instruments. Digitising these
plates in an optimal way is crucial to the
accuracy of the data."
National Geographic Institute at the old Ter Kameren abbey in Brussels
Used with kind per
mission of N