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New perspectives to save cultural heritage
Altan, M. Orhan

CI PA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
necessary to process each one separately. It is preferable to
create these nets before photographs are taken, although it is
possible to take printed versions of the digital photographs back
to the field and measure marked distances. Once rectified in
AERIAL 5.3, each of the individual photographs were imported
into AutoCAD, the control points and lines matched to the
drawing and each image cropped as necessary to form a photo
mosaic (Fig. 1). The wall elevation thus produced can be
digitised on screen or inked by hand over a scaled printout in
the comfort of the office. The number of individual photos
depends on the level of detail required, the size of the wall, and
the space available for taking the photo (in this case restricted
by the narrowness of the trench).
Photogrammetric recording and some photography of the Iron
Age cyclopean granite masonry used for the Cappadocia Gate
at Kerkenes was done in 1999 and 2000 and reported at CIPA
2001 (Baturayoglu 2001 and Baturayoglu et al. 2001). In 2002,
as excavation of the gate passage continued, the side walls to
the entrance were recorded in the way just described, using a
quality digital camera (photos of 2032 x 1536 pixels) once
control points had been chalk-marked and measured (Fig. 2).
Figure 2. (a) The location of the section across the passage of
the Cappadocia Gate at Kerkenes Dag;
(b) Excavation revealed the addition of the glacis to the front of
the north-east passage;
(c) Accurately measured control points and lines are used for
(d) The drawing, by Gülnur Uçar, was inked over the scaled
printout of the rectified photograph.
3D modelling of the part of the stone glacis, using
PhotoModeler, also produced encouraging results. It was
concluded that, as had been anticipated, the results obtained
from a digital camera with a good resolution were preferable to
scans made from prints or colour slides (Fig. 3).
(a) (b)
Figure 3. A model of part of the glacis at the Cappadocia Gate
produced in PhotoModeler from (a) digital photos and (b) scans
of black and white photos. These 3D models, generated in
PhotoModeler by Refik Toksoz, can be viewed from different
2.2 Planning Stone Pavements
This same technique was particularly successful when used to
record an extensive area of excavated stone pavement at
Kerkenes in July 2002 (Fig. 4). Traditional recording
techniques involve the tedious and time-consuming task of
making pencil drawings, with the help of a planning frame
(usually lm x lm), showing each stone in plan at a scale of
1:20. The technique that was developed uses digital
photographs of each lm by lm square of pavement together
with grid points surveyed with a Total Station. The slope of the
pavement was sufficiently gentle for the rectification of photos
over a plan view using the (x,y) coordinates obtained with a
Total Station. Photographs were taken from the top of a
stepladder in order to have sufficient coverage for use of only
the central portion of each photo, which has minimal distortion.
Chalk marks on the stones or nails with white and/or red tags
were used as control points placed at the corner of each grid
square. AERIAL 5.3 produces grayscale images (Fig. 4b and c)
which were aligned over a grid in AutoCAD to complete the
mosaic. The mosaic can be printed at scale and a hand drawing
made (Fig. 4c).
Other techniques used more sophisticated GIS software (Arc
View and ERDAS Imaging) to produce photo-realistic colour
2D images and 3D models. Ground control points are either
measured with a Total Station, using a local coordinate system,
or plotted by a GPS in UTM (Universal Transverse Mercator)
or similar system. To create a colour photo mosaic of the entire
pavement area, ERDAS Imaging was selected (Fig. 4d). The
polynominal transformation can translate the photo to any
coordinate system, rescale, rotate and skew. A 1st order
transformation or rubber sheeting method requires a minimum
of three control points on the photo although four points are
preferred. When all control points are generated within the
same coordinate system, different images can be combined with
ease into a photo mosaic generated in 3D or, if desired, in 2D as
a plan. Points and vector drawings can be opened
simultaneously in different windows and control points matched
on screen or using a table. A photo realistic plan of the stone
pavement exposed at Kerkenes by the Palace Complex glacis
was thus generated (Fig. 4d).