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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
* dgn files produced by the digital photogrammetric workstation 
as byproduct of the rectifications and the orthophotography 
productions. 
All surfaces were exported from AutoCAD to 3D Studio Max 
for the photorealistic rendering to be carried out. The layering 
of the surfaces was performed utilizing imaging material from 
the project of the geometric documentation, suitably processed 
with the help of Adobe Photoshop v6.0 software. This material 
was raster orthophotographs of very high resolution and quality, 
thus setting a very high standard for the quality of the textured 
model as a whole (Figure 7). 
  
Figure 7: The textured model 
For the realistic visualization of the interior, especially of the 
magnificent mosaics, their orthophotos were used. They were 
suitably processed within the Macromedia Fireworks MX 
environment, in order to artistically adapt their colours to 
reality. The orthophotographs of the mosaics appearing on 
complicated surfaces, were “cut” accordingly, in order to 
enhance the final product. 
4. CONSIDERATIONS FOR THE FINAL RENDERING 
In order to complete the project, a virtual tour of the exterior 
and interior of the church was planned, using the 3D StudioMax 
animation tools. To achieve a realistic feeling for the tour, a free 
50 mm lens camera was selected for the exterior and a 28mm 
lens camera for the interior. The paths of the camera movement 
were predefined by selecting a certain number of animation 
keys which guided the cameras around the main parts of the 
Church. Emphasis was given to certain parts of special interest 
by foreseeing suitable zoomings, as e.g. in the case of the fine 
mosaics (Figure 8). 
  
: The mosaics of the interior 
Another important factor to be considered is lighting. It has 
been found out that the predefined lighting usually proposed by 
the software does not always guarantee the best result. Hence 
lighting should be chosen with the object in mind. In the present 
case four ambient “omnilights” proved to give a better 
impression than direct sunlight, as one might assume. The 
aesthetics of the camera shots were finalized by lighting 
individual angles of the tour, thus giving character and realism 
where needed. The lighting of the interior part of the tour was 
particularly difficult. Ín order to simulate the complicated real 
lighting conditions, a combination of lighting tools was finally 
used after several trial and error efforts. 23 different light 
sources were finally used, with suitable parametrization of their 
attributes, such as intensity, colour, direction etc. (Figure 9). 
  
Figure 9: Light source distribution for the interior 
Last, but not least, is the question of choosing the proper 
surroundings. It may be easy — and lucrative — to produce a 
realistic simulation of the ground surface and layer it with 
suitable aerial images. However, this may lead to excessive 
results and a more subtle and neutral background should be 
preferred. For the interior a neutral background was chosen for 
the various walls without mosaics, in order not to distract the 
viewer. 
With a frame rate of 25 frames per second, the duration of the 
final video resulted to 6 minutes and 30 seconds. The tour starts 
outside the church and aftre completing a full circle, enters the 
Katholikon. The path is chosen in a way to enable the virtual 
visitor to understand the space inside the church, the 
construction of the church, but also to be able to admire the fine 
mosaics via selected zoomings to the most important of them. 
The video has an analysis of 640x480 and uses the Indco® 
Video 5 compression format. Compression was necessary, as 
the quality and resolution of the images are directly related to 
the size of the final animation. In order to achieve maximum 
video quality the frames ought to remain uncompressed and the 
result would be a file of approximately 2GB. This would mean 
that the final product would need.special storage devices and a 
lot of free space on the hard disk in order to be reproduced. 
Moreover uncompressed images lead to unacceptably long 
rendering procedures. Therefore it was necessary to compress 
the images using a certain compression format, which would 
maintain the quality of the final rendering, while keeping the 
size of the video file to a minimum. The time needed for the 
rendering to be performed is also dependend on the technical 
specifications of the computer used.