ON SOME ASPECTS OF TAKING CLOSE-RANGE PHOTOGRAPHS
FOR PHOTOGRAMMETRIC EVALUATION
PRACTICAL EXPERIENCES IN PHOTOGRAPHING
THE MODELS OF THE CABLE-NET ROOFS
FOR THE OLYMPIAD AT MUNICH
Ing. W.-U. BOTTINGER,
University of Stuttgart
The application of close-range photogrammetry to the evaluation of the models of the prestressed cable-net roofs
of the olympic sports facilities serves as an example to show practical aspects of close-range photography. Considera-
tions for the camera set-up, lighting, control point determination and image scale are included and experiences gained
are discussed.
La restitution de modéles de construction de réseaux précontraints pour les centres sportifs olympiques de
Munich est un exemple particulièrement démonstratif des possibilités d'application pratique de la photographie à courte
distance. Les considérations relatives au schéma de prise de vues, aux points de contrôle et à l'éclairage du sujet sont
traitées, et les résultats de cette expérience sont discutés.
Am Beispiel der photogrammetrischen Vermessung der Modelle der vorgespannten Seilnetzkonstruktionen der
Olympiadächer werden praktische Aspekte der photographischen Aufnahme aufgezeigt. Überlegungen und Erfahrungen
zur Aufnahmedisposition, Passpunktbestimmung, Beleuchtung und zum Bildmassstab werden mitgeteilt.
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Remarks about the models
The roofs of the olympic sport facilities - stadium, athletic arena, and swimming hall -
and the roof of the olympic center connecting stadium and athletic arena were drafted and built
as light-weight structures, For the development of the geometrical shape and for determination
of the cutting pattern of the prestressed cable-nets models at scale 1:200 and 1:125 were construc-
ted at the Institute of Light Weight Structures (IL) of Prof. Frei Otto, These models were to have
geometrical and elastical properties similar to those of the roofs at the site of the buildings.
The first type of models was made of a polyester fabric and served only in the geometric
form finding process. In a second step "measuring models" were built in which the surface was
realized by a net of steel wires with equallengths of meshes of about 24 mm, except of the boun-
dary areas, In these measuring models the final geometric figure of the roofs was realized, and
it was also possible to judge the behaviour of the nets under loading conditions after determination
of the wire tension. The results of this step were used to construct the "cutting pattern models"
which were to be transferred into reality.
The models of the athletic arena, the swimming hall, and the olympic center consist of
a rectangular frame of about 2. 0 x 1.5 m2 reinforced by several struts. On the struts the founda -
tion points of the masts bearing, the net and the bracing anchors were mounted,
The model of the stadium was considerably larger ; its size was about 3.3 x 1.7 m2, The
vertical extension of the net above the frame was about 0. 7 m in all models,
All points of each model that should be measured were classified in net intersections,
boundary cable points, and system points. The net intersections are formed by two net cables X 4
realized in the model by spring steel wires with a diameter of 0.2 mm lashed with copper wire. 0 4
In the boundary cable points the net cable and the boundary cable were soldered, The system
points can be classified in intersections of two boundary cables, intersections of boundary cables
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