712 
Petsa, Kouroupis, Karras 
For creating the sequence following parameters were used. The size of the frame had a typical proportion (1440 x 1152 ). For the 
“rotating video camera” a camera constant c = 1875 pixels was used. The sequence concludes with a zooming of the “stationary 
camera” on the inserted building, during which the camera constant was finally doubled. The constant shift of the principal point, 
mentioned above, was Ay 0 = 200 pixels. Finally, the camera rotation about the vertical axis had a range of f max - f min = 82°, whereby 
successive frames had a step of A(f> = 0.25° during the rotational movement. The final video consists of about 800 frames in total and 
runs at a speed of 25 frames/sec. 
6. FUTURE TASKS 
In the present contribution simple monoscopic techniques have been combined to create an “artificial” video sequence showing a part 
of the central square in Athens, which has been largely rebuilt in the last decades. Cocentric images were acquired, mutually rectified 
and mosaicked into a panoramic image. The 3D model of a demolished building was reconstructed, photo-textured and then 
introduced into the panoramic image. The resulting image was used to generate frames which were finally combined into a sequence. 
This experience indicates the possibility to employ simple means for generating a product which, although not highly accurate, is 
visually powerful and hence very useful in architectural and archaeological representation. 
A question encountered has to do with the somewhat non-uniform perspective of the panoramic image, which might be attributed to 
the fact that the overlapping images were only approximately cocentric. If no panoramic camera is used, image acquisition may cause 
such difficulties. Besides, imprecision may be also explained by errors of manual measurements during rectification (image matching 
is an alternative). Furthermore, the wide-angle lens used here has introduced significant lens distortion. This may be avoided by using 
normal lenses or by correcting distortion with one of the simple methods available. As a consequence, the reconstructed building did 
not fit perfectly into the panoramic perspective. Such questions will be taken into account in the next steps of this work. The intention 
is actually to reconstruct all buildings of this historic square for which old photographs are available. This reconstruction will be used 
both to produce more complete video sequences derived from images taken today but also to fully model the site and produce VRML 
models in a fully virtual environment. 
ACKNOWLEDGEMENT 
The authors wish to thank the Photographic Archives of the Commercial Bank of Greece, the National Gallery in Athens and the 
Benaki Museum for providing most of the photographs used in this project. 
REFERENCES 
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