with a Tethered Blimp
Survey at Kerkenes was initiated because it was thought that a plan
of the extant remains could be obtained with relative speed and at
comparatively little cost by the employment of remote balloon borne
photography. Experimentation at Yarasli in 1991 had shown that this
was possible (Summers and Summers 1992; Summers 1992). Balloon photography
was a viable alternative to aerial photography from planes, for which
it is still impossible to obtain permission in Turkey. At Kerkenes
photography with a blimp was completed in only two seasons, 1993 and
94, with a few holes in the coverage being filled with a kite in 1997.
Equipment and Method
Equipment used at Kerkenes was unchanged from that described in detail
in Summers 1992. Today we would use lighter equipment and perhaps
groups of smaller balloons or, better still for such a large site,
a motorised paraglider. We would also use narrow angle lenses because
they give less distortion. Essentially we used a helium-filled advertising
blimp to carry a sling containing an Olympus camera with an automatic
winder and a model aircraft radio control to fire the shutter. On
still days, about one third of the days at Kerkenes in the summer
months, the blimp could be flown in a series of traverses at altitudes
of around 300m. Operators can usually hear the shutter or rewind with
each frame so that, with a little practice, good sets of overlapping
pictures can be obtained. On really still days, and with some courage,
the blimp could be flown at altitudes approaching 800m. using a strong
kite line rather than a rope for the tether (because the maximum height
attainable is largely limited by the weight of the tether). Targets
on the ground, in our case marked with white lime and plotted with
a total station, permitted rectification.
Results from blimp photography include:
1 High level oblique pictures that are great aids to interpretation
and are, at the same time, visually striking. Results are, however,
somewhat hit and miss since the operator has to estimate both the
direction and the angle of the camera when the shutter is fired.
2 High level vertical photographs that can be rectified and used for
mapping visible features.
3 Low level vertical photographs that can be rectified and used for
detailed interpretation and mapping of visible structures.
Aerial Photography from
a Manned Hot Air Balloon
The advantages of flying the photographers over the site are self-evident.
Restrictions are cost, availability and weather. Civil aviation authority
is required in addition to the research permit from the Ministry of
from the Turkish Directorate of Land Survey and Registration
The Directorate of Land Survey and Registration (“Tapu ve Kadastro”)
has stereo aerial photographic coverage of much of Turkey. These photographs
are, however, subject to very strict security control that effectively
makes them unavailable for archaeological research. Other official
bodies in Turkey also have photographic archives that are subject
to the same controls. MNG Ltd, however, had the requisite security
authorisation to obtain a set of photographs of the Kerkenes Dag from
which they most kindly made three-dimensional digital map of the site.
Production of this map was crucial to the development of the project.
Completion of the Global Positioning System (GPS) survey in 2000 should
make the earlier MNG map redundant, but the size of the GPS data files
and the complexity of the GPS software mean that the simpler map is
still extremely useful.
Aerial photographs need to be rectified before they can be used to
compile maps. Failure of the camera support to hang vertically below
the blimp, in such a way that the camera is precisely parallel to
the ground, is the most important cause of distortion. Lenses also
distort images, and the wider the angle of the lens the greater the
At Kerkenes we have relied
on AERIAL software produced by John Haigh from the Department of Mathematics
at the University of Bradford. This program is able to rectify single
images provided that there are at least five known points on each
picture. We have rectified actual photographs and, more usually, rectified
features traced from photographs. Software and hardware are advancing
so rapidly that there is not yet a set or standard procedure.
Our present target is to
drape our aerial photographs, and the interpretative plans made from
them, over GPS images.