The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008 
Figure 3. Terrestrial laser scanning of Erechtheion, showing 
some of the difficulties (El-Hakim et al., 2008). 
3. PRELIMINARY RESULTS 
As mentioned above, the project is still on-going. Preliminary 
results are reported in more details in Tsingas et al. (2008), El- 
Hakim et al. (2008) and Remondino et al. (2008). 
A few thousand of balloon images have been acquired for top 
views of the hill, but also the walls and the rock. After camera 
calibration, triangulation and orientation of the images, Digital 
Surface Models (DSMs) and orthoimages have been produced, 
with examples shown in Figures 4 and 5, respectively. 
Terrestrial laser scanning has been performed for the walls 
(from outside and inside) and the rock. An example of the 
textured laser scanner point cloud in shown in Figure 6. 
Regarding the Erechtheion, more then 5 billion points have 
being collected by laser scanning. This amount of data is 
impossible to handle, as a whole. A reduced, but still large, 10 
million polygon model has been produced. Image-based 
modeling results of the Erechtheion are shown in Figure 7. A 
detail from the high-resolution, full 3D model showing one of 
the Caryatid statues is shown in Figure 8. 
Figure 4. A detailed part of the DSM generated by balloon 
images on the Acropolis (Tsingas et al., 2008). 
Figure 5. Detail of an orthophoto from balloon images (Tsingas 
et al., 2008). 
Figure 6. Part of the laser scanner point cloud in the south wall 
(Tsingas et al., 2008). 
Figure 7. Results of the image-based 3D modeling of the 
Erechtheion shown in wireframe, shaded and textured mode 
(Remondino et al., 2008).