ERATO Proceedings Istanbul 2006.pdf - Odeon

oofing, the works of Izenour [11] were used instead, due to a more solid hypothesis regarding this
part of the theatre.
3.2 Modeling and texturing
For the realization of the 3D model of the Aspendos site, polygonal modeling techniques were
preferred. Critical parts of the model, such as the Cavea, due to its extremely complex geometrical
features, were given special attention to keep an acceptable trade-off between visual accuracy and
the performance of the real time simulation. In order to model the Aspendos site virtual
environment, accurate topographic data was provided in the form of a 2D elevation map of the area
featuring elevation lines every 1 meter. After the repositioning of these splines in a 3D space, it was
possible to build a high polygon 3D mesh (80.000 polygons) from which a greyscale elevation map
has been extracted to procedurally generate the diffuse textures of the terrain using distribution
parameters such as relative height of the polygons, their orientation and their slope.
Figure 3: low polygon optimized mesh of the terrain (left), textured 3D model (center and right).
In order to meet the needs of a real time simulation, a simplified version of the 3D model of the
terrain (4.500 polygons) has also been prepared (figure 3) through automatic optimization and
manual refining to be mapped with the previously prepared procedural texture. Using as a base the
on-site taken high resolution digital photographs, the creation of a library of the main identified
diffuse material textures present on the site has been made: 150 different color corrected textures
that can be tiled seamlessly on the objects of the 3D scene have therefore been prepared (examples
shown in figure 4).
Figure 4: Samples from the texture gallery (left), 3D scene building with and without textures (center and right)
Unlike the process applied to create the textures for the Hagia Sophia building in the frame of the
CAHRISMA project [7], for the Aspendos site virtual restoration was not considered: the edifice
features in fact little, or none, colored decorative motives, and generally the surface materials consist
of stone pattern variations.
3.3 Edifice Visualization and virtual Restitution
As previously introduced, two models of the Aspendos theatre were developed in order to
visualize the site in its present state and as it was back in the III century. The main difference
between these two versions of the model resides in the elements that were present at the Roman time
and that are now no longer present, such as the Velum, the roofing of the theatre and all the