UN
nation.
cant restoration
of the sanctuary
t the uppermost
man eras in the
| sections of the
c geometry. As
ient dating from
»nysus had been
| transformed to
ns and methods.
f the necessary
he photographic
isation and the
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y procedure for
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LTS
cient theatre of
ure exploitation
xploited for the
nument and for
ge of the image
as well as the
ohs were taken
n conditions in
faces, while not
NON, f: 45mm,
r geometric and
1:300, while the
5, with 12 to 14
delineated level
of the monument, with 70% alongside and 35% wide side
overlapping.
Figure 1. Theatre view
22 Photogrammetric Acquisition
The photographs were taken in May, with criterion the
distinctness of the restituted object. Advantages of the natural
lighting and choice of the suitable time were considered so as to
avoid shadows and samplings with different technical
characteristics in order to achieve the best results during film
development.
The main problem during image acquisition was to find the best
way for the photogrammetric camera's elevation. The initial
plan was to use the WILD P31 metric camera, in combination
with a vehicle having a suitable nacelle. The high elevation
contrast of the monument (about 40m) with regards to the
surface of the monument did not permit the implementation of
the initial planning.
The use of *a balloon" carrying a special construction for
holding the camera, which should be lighter than WILD P31,
was chosen as the best technical solution. For that reason, the
FUZIFILM GA645W1 camera was chosen, which although is
of a less format, it is five times lighter than WILD P31.
Figure 2. Image acquisition from the balloon.
The camera was raised to a height of 19m, while it was held
vertically over the shooting point by special strips of variable
length depending on the conditions.
Figure 3. The rest for the camera with stabiliser.
The critical part was that, concerning the geometry of the image
acquisition. For that reason, the image centres (Nadir points)
were marked so that the initial planning of image acquisition
was followed.
Figure 4. Image centre.
Moreover the above marked centres were geodetically
calculated so as to enable their use as ground control points
(gcp's). Thus, there was a need for 36 more points, which were
placed perimetric to the photogrammetric block. All images
were acquired in colour.
2.3 Geodetic network — calculation of GCP'S
Simultaneously with the acquisition planning a set of gcp's
were marked in advanced targets with dimensions 5cm x 5cm,
in such a way that could be visible in the images.
These points were coded according to the corresponding
number of flight strip that they were depicted. The methodology
that was followed for the measurement and their adjustment for
the calculations of the coordinates was the same with that used
for the polygonometric and checkpoints network.
For the needs of the restitution, a net of points of high accuracy
in horizontal and the vertical level should be measured and
computed. The network covers a horizontal area of about 130m
x 130m, while it was also extended to the outer sides of the
monument which were included in the above surface.
The network points, which include the trigonometric —
polygonometric points and the gcp's, create a “grid” with a cell
size of about 2—5m, covering the whole monument's area.
Initially, there were established and materialised two (2) new
trigonometric points in the monument's area. These points were
placed along to the theatre's axis, in the lowest and highest
level, correspondingly, covering in visibility the whole
monument.
The polygonometric network was drawn and materialised in
such a way that would include all the surrounding points of the
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