International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
    
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Figure 7. Example of 2D AutoCAD map from the tacheometric 
survey of 2002 (level 4 of the castle). 
  
Coupe 11 
Figure 8. Example of 2D AutoCAD section. 
4. PHOTOGRAMMETRIC DATA PROCESSING 
4.1 Multi-image photogrammetry 
Photogrammetric solutions (Grussenmeyer et al, 2002) are 
either based on the processing of single images (e.g. image 
rectification of plane objects), stereoplottings (for stereopairs of 
photos), or multi-image restitutions when a set of convergent 
photos of an object is available. The last solution has been 
chosen for our project in order to process in one block the sets 
of photos taken from the different types of cameras. We used 
the PhotoModeler software package from EOS System 
(Canada), well known for its applications in close range 
photogrammetry, architecture and archaeology. 
The preparation steps in order to process the images were the 
following: 
- definition of the “camera” file for each type of camera: the 
« camera calibrator » module of PhotoModeler has been used 
for the calibration of the digital cameras; 
- for the archive images, an approximate camera file has been 
edited (camera with four fiducial marks) for further “on the job 
calibration”; 
- edition of the control point table (from the geodetic survey); 
- scan of the film or paper-based images (for the set of archive 
images and the color slides from the Nikon F3 camera). 
The basic steps in this type of project performed with 
PhotoModeler are : 
- choice two or more overlapping photographs from different 
angles of the object ; 
- use the point and line tools to mark on the photographs control 
and tie points; 
- reference the points by indicating which points on different 
photographs represent the same location on the object 
(homologous points); 
- process referenced data to produce 3D model; 
- check the adjustment and view the resulting 3D model in the 
3D viewer ; 
- extract coordinates, distances, curves, surfaces, textures etc. 
within PhotoModeler ; 
- export the 3D model to rendering, animation or CAD 
program. 
4.2 Calibration of the cameras 
Four types of images are used for this project: 
- images from a Nikon Coolpix 5000 camera used in the 
extreme positions of the zoom (7mm and 21mm). This camera 
was calibrated in the two positions using the calibration grid 
proposed in the PhotoModeler software (module "camera 
calibration"); 
- images taken with a traditional reflex camera Nikon F3, 
equipped with a Nikkor 55mm objective. The calibration was 
carried out like previously after scanning the slides of the 
calibration grid; 
- images (prints or copies of film, see paragraph 3.1) of 1930- 
1936 scanned with a resolution of 900dpi: unfortunately no 
photogrammetric information on the characteristics of the 
cameras used has been found. Several types of glass-plates- 
based cameras with focal distances of 20 to 30cm were used at 
that time for the acquisition of aerial and terrestrial views 
(Roussilhe, 1936). The focal length of the camera used for this 
archive images is written on the border of the image (26 cm) 
and the original size of the images (glass plates in the 1930's) 
was supposed to be 24 cm x 18 cm. 
4.3 Adjustment of the block of the images of 2003 
More than 130 images were realized in spring 2003 with the 
Nikon F3 and Nikon Coolpix cameras (a hundred images on the 
ground and about thirty in the helicopter). A first block of 18 
oblique views of the castle was oriented in June 2003 using the 
control points materialized on the ground by targets (figure 6). 
Standard deviations of about 10 cm on the co-ordinates of the 
points measured on the images have been obtained. We then 
selected in this project a set of points simultaneously visible on 
the images of 1931-1936, in order to define approximations of 
the photogrammetric parameters, and to calculate a block based 
on a selection of these archive images. 
4.4 Adjustment of a block of archive images 
Initially we selected 5 oblique photographs (approx. scales of 
1/1000 to 1/2000) in order to document archaeological vestiges 
of the North and West parts (Grussenmeyer & Yasmine, 2003). 
The approximate values of the internal and external orientations 
of the archive images have been computed within the module 
"process & autocalibration" of PhotoModeler with the help of 
control points defined in $4.3. 
4.5 Merger of the two projects and preparation of the 
restitution 
At this stage, the two separately calculated projects are referred 
to the same reference system. The process of merging (ol 
several projects) proposed in the PhotoModeler software allows