CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
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4. 3D MODEL VISUALIZATION
Different tools are available to display 3D models, shareware
and commercial software, with or without real-time
performance, interactive or not. Often the visualization of a 3D
model is the only product of interest for the external world and
remains the only possible contact with the model: therefore
visualization packages are very useful and must provide very
realistic views.
The final 3D model generated with manual measurements is of
rather big size and consists of ca 452 000 triangles.
One of the few portable formats to interactively display a 3D
model like the reconstructed Buddha statue is the VRML. With
free packages like Cosmo Player or Vrweb we can display and
navigate through the model or automatically fly along some
predefined paths (Figure 13). The final VRML model of the
Great Buddha, including also part of the surrounding rock,
occupies ca 98 Mb.
Figure 13: Visualization of the Buddha model with an Internet
browser plug-in (Cosmo Player)
Computer animation software (e.g. Maya) is generally used to
create animations of 3D models. An example is presented in
http://www.photogrammetry.ethz.ch/research/bamiyan/anim/bu
ddha.mpg.
Finally, a way to display attractive static views of 3D models is
based on anaglyph images. An anaglyph mixes into one image
a stereoscopic view using the complementarity of colours in the
RGB channels. With coloured glasses, one can then filter the
image and see the depth information of the model (Figure 15). 5
5. PHYSICAL RECONSTRUCTION
The 3D computer model that we generated with the manual
procedure is used for a physical reconstruction of a scaled
model of the Great Buddha. At the Institute of Machine Tools
and Production, ETH Zurich, R.Zanini and J.Wirth have created
a 1:200 model statue of the Great Buddha (Figure 14, right).
The point cloud of the manual photogrammetric reconstruction
is imported in a digitally programmed machine tool (Starrag
NF100). The machine (Figure 14, left) works on polyurethane
boxes and follows milling paths calculated directly from the
point cloud. The physical model is created in three steps: (1) a
roughing path, (2) a pre-smoothing path and (3) the final
smoothing path. The time needed for preparing the production
data was about 2 hours while the milling of the part itself was
done in about 8 hours.
Figure 14: The milling machine used for the physical
reconstruction of the Bamiyan Buddha (left) and an image of
the 1:200 model (right).
6. CONCLUSIONS
The computer reconstruction of the Great Buddha of Bamiyan,
Afghanistan has been performed successfully using digital
photogrammetric techniques. We have presented here the
results of the 3D model, based on automated point cloud
generation and manual measurements on three metric images.
But we produced also accurate results using simple Internet and
tourist images where typical photogrammetric information (as
interior and exterior orientation parameters) was not available.
While automated matching methods provide for dense point
clouds, they fail to model the very fine details of the statue, e.g.
the folds of the robe. Therefore, only manual measurements
allowed to generate a 3D model accurate and complete enough
to serve as the basis for a possible physical reconstruction in
Bamiyan.
We also reported how digital photogrammetry can be used to
recover 3D models or technical documentation of historical
monuments and sites. As next steps in our work we plan the
following tasks:
• Measurement of the cave surface (backside of the Buddha
after destruction);
• Generation of a photo-realistic 3D model of the cliffs and the
extended vicinity;
• Modeling of the frescos inside the Great Buddha cave;
• Preparation of flyovers and animations.
Before the physical reconstruction of the Great Buddha in
Bamiyan can be performed the damaged and endangered cliffs
around the Buddha cave have to be stabilized. This is currently
discussed at UNESCO and in other international circles.
A web site of the work has been established on our server and is
available at
http://www.photogrammetry.ethz.ch/research/bamiyan/
with more technical details and animations.
ACKNOWLEDGEMENT
The authors would like to thank Yuguang Li for the manual
measurements on the metric images, Robert Zanini, Joachim
Wirth and the Institute of Machine Tools Production, ETH
Zurich, for the physical reconstruction of the statue at scale
1:200, Tom Bilson, Courtauld Institute of Art, London, for
