Full text: New perspectives to save cultural heritage

CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
Figure 2. The camera and its special-designed platform 
Figure 4. Balloon during flight campaign 
For all the theater, 214 aerial and 275 terrestrial photos are 
taken. Aerial photos have been used for mapping the plan where 
terrestrial photos for evaluation of facades. 
On the aerial photos, ground control points are clearly visible. 
This was the result of painting them blue, so that the effect of 
reflectance had been minimized (Figure 5). On terrestrial 
photos, there wasn’t a reflectance of control points, because 
onto them as a measure marks. 80 ground control points were 
used for all the theater. (Figure 1) 
Another type of control points was defined for the terrestrial 
photogrammetry for facades. Comers of stone blocks have been 
chosen for this purpose. 
All of them have been measured by terrestrial methods with a 
total station Pentax ATS 102. 
Figure 1. Layout view and control points 
2.3 Image Acquisition 
Aerial images have been acquired from a helium balloon with 
an Olympus C-4040. Balloon was 2.5 m in diameter and has a 
volume of approx.8 m 3 . It can lift up to 8 kg, so the 
optimisation of platform and the camera on the balloon has a 
big importance about the weight of them. The camera and 
platform have been selected and built so that their weight will 
be minimum. Even the ropes have been selected so that they 
would be strong enough for this balloon and minimum in 
weight. 
The balloon carries an aluminium frame as a camera platform 
and this platform is hanged downside of the balloon using 6 
ropes. The camera platform was built in the workshop of GGS 
in Speyer. The digital camera was fixed at a axe, which itself 
was connected to the triangle frame, turn able around 2 axes so 
that the weight of the camera forced the platform, to support 
always a nadir view of the camera (Figure 2). To reduce the 
swinging of the platform, a smooth-compensator was built in. 
Phi and Omega values should be small with this construction, 
Kappa had to be influenced by the rotation of the balloon. 
To the ground the balloon was fixed with 3 ropes, each with 
50m length. One rope was used as carrier for a video and a 
remote-control wire. 
The video-out port of the camera was used to transmit the 
cameras view to the ground. The normal PAL-signal was send 
through a coaxial wire. A small portable TV with a video-in 
plug and battery power was used as a cheap monitor solution. A 
frame protected the screen against direct sunlight and the 
control worked fine (Figure 3). 
Figure 3. Ground control unit with monitor and remote control 
The wireless infrared control of the camera was rebuilt and the 
IR LED was connected to a thin wire and fixed before the 
Sensor at the Camera. IR signal only bridge short distance (max 
10 m) and have problems in hot air conditions. Both worked 
fine even with 50 m wired connection, video control and the 
remote control of the camera. Also the sharpness of an image 
has been visible when the image was frozen for a few seconds 
when the camera had shot the photo.
	        
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