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1. THE DATA CAPTURE SYSTEM 
As no aerial view was available and there was no relief 
overlooking the site, we planned a close-range coverage 
(fig.2) with a camera set at the end of a portable L- 
shaped bracket built by ENSAIS (fig. 3). 
  
Fig.2 : nadiral photograph on a monument 
Camera 
  
v 
Comera axis 
h Bull’s eye bubble 
  
  
Fig. 3 : the portable L-shaped bracket 
A Ricoh KR 10 M reflex camera (24mm x 36mm format) 
was turned into a measuring tool after some 
enhancements : calibration on a set of targets for a 
blocked focus at the test field of ENSAIS, and accurate 
setting of 4 fiducial marks (designed by PMS AG, 
Switzerland). 
The mean radial distortion graph of the lens (28 mm 
focal length) was drawn up with the Orient Software. 
dR(mm) 
   
Fig. 4 : the Ricoh KR 10M camera with its four fiducial 
marks and the radial distortion graph 
201 
The camera is screwed onto a small plate at the end of a 
single solid angled support (bracket) made of assembled 
pieces of metal allowing a maximum shooting height of 
6 metres (value chosen for best efficiency). 
The consequent 1/210 image scale is most suitable for 
precise work with enlargements of up to 1/50. 
With pieces shorter than 1.50m and a total weight under 
20 kg, the bracket can be easily transported by plane. 
  
  
  
  
Camera height | coverage area image scale 
above ground (m x m) 
4m 3,4 X 5,1 1: 140 
5m 4,3 x 6,4 17180 
6m 54x77 4: 210 
  
  
  
  
  
Tab.1 : fields and scales allowed by the data capture 
system with a 28mm focal length 
The bracketing option of the Ricoh camera enables 3 
snap-shots to be taken in a row with 2 versions slightly 
more or less exposed than the standard one, in order to 
improve the chance of getting the best contrast. 
Two or three people are necessary for handling the 
bracket while the operator releases the shutter with an 
infrared remote device. 
  
  
Fig. 5 : surveying the curia 
The verticality of the camera axis needs not be perfect 
since its true spatial position will be computed during the 
bundle adjustment before the stereoplotting ; the support 
set up is estimated with a bull's eye bubble and the 
spatial position of the camera can be easily adjusted 
with a screw. 
Meanwhile, before starting the survey, one has to check 
what is really recorded by the camera when vertical, by 
means of targets on the ground. 
For this reason, but also for a quick retaking of a 
possibly missed photograph due to the hazards of the 
operations, photographs must be processed in the field : 
black and white Agfapan 100 Asa films were used. 
Where colors were required to help interpretation, a 
second coverage was made with Ektachrome 200 Asa 
slides which were stored later on CD Rom with Kodak 
CD Photo system [Hanke, 1994] for possible further 
processing. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996