62 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1976
d tony we + + 574 <8
Frc.6. A much reduced copy of the plotted
west elevation of Huby's Tower, Fountains
Abbey, Yorkshire. The distance between
neighbouring grid intersections is 5 m. The
original plot was at a scale of 1:50. Structural
weaknesses and masonry cracks are clearly
shown and are most numerous just below
the lower Latin inscription.
photogrammetric analysis in recent years.
The work of Professor K. Linkwitz and his
colleagues atthe University ofStuttgartis well
known in connexion with the digital model-
ling of roof structures for the Montreal Expo
67, the Munich Olympic Stadium and, re-
cently, the Mannheim garden exhibition
(Linkwitz, 1967; Linkwitz and Preuss, 1971
and 1974; Happold and Liddell, 1975). At
University College London, we have been
involved in two modest experiments, one of
whichanalysed the effectof wind deformation
on model high rise flats and the other deter-
mined the geometry ofa 1:50 scale model ofa
prestressed cable roof. This experimental in-
vestigation, fully described by Nooshin and
Butterworth (1974), related to a cable roof
which now provides partial cover for the
Farahabad sports stadium near Teheran. The
roofconsists ofa number of suspension cables
which are connected atone end toa reinforced
concrete spatial beam and at the otherend to a
flexible cable which is in turn supported by
two pin-ended steel pylons. A family of pre-
stressing cables is arranged orthogonally to
the suspension cables. The objectofthe inves-
tigation, carried out in the Space Structures
Research Centre of the University of Surrey,
was to check the preliminary design and to
provide information for the final design of the
cable roof. The detailed shape of the net was
determined at one stage during testing by
employing close-range photogrammetry (At-
kinson, 1972a). Stereometric photography of
the model and five premarked control points
was taken with an Officine Galileo camera
mounted on the laboratory ceiling above the
model (Figure 7). From observations in a
Thompson-Watts Mk.2 plotter, the co-
ordinates of all points of cable intersection
were determined with a standard deviation of
+ 0.1 mm in plan and + 0.3 mm in elevation.
The photogrammetric technique provided a
simple and elegant solution to a measure-
ment problem which would have been dif-
ficult to solve by other means.
A PHOTOGRAMMETRIC WRIGGLE SURVEY
In recent years, construction has been tak-
ing place ofa new twin tunnel underthe River
Mersey between Liverpool and Wallasey.
The consulting engineers, Mott, Hay and An-
derson, were in possession of suggestions for
the provision of a photogrammetric wriggle
survey made by the Swedish photogrammet-
rist, Dr. (now Professor) K. Torlegàrd. In order
to test the feasibility of this scheme, we were
FiG. 7. One photograph of a stereopair of the
structural model ofthe Farahabad stadium roof.
Five control points may be seen, as well as the
207 cable intersections which were co-
ordinated.
