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CIPA 2005 XX International Symposium, 26 September - 01 October, 2005, Torino, Italy 
is often larger than density for high resolution views. Accuracy 
of laser scan Ilris 3d (Optech) is lesser than accuracy of a 
modem global station, but the acquisition time is much lesser 
and density is considerably larger than a motorized global 
station. Thus, there is a greater productivity and facilities for the 
integration of high resolution scanning files in larger 3d models. 
Some advantages of laser scanning photogrammetry and 
dedicated software (Polyworks Inc) are linked to a larger 
density, radiometric information in original files and the 
friendly user interfaces for basic processing. 
An important bottleneck concerns to the management of very 
large datasets, and the necessity of reducing information 
(sometimes in a dramatic way) for displaying and navigation 
around the object. In this work, we have developed an approach 
to volumetric primitives which depends strongly on the 
expected geometry for the visible boundary (plane, cylinder) of 
the object. Choice of geometric primitives imposes additional 
constraints, which must be avoided in the near future. 
Obviously, there is a long way for pendant research still, which 
concerns in particular to the fusion of information arising from 
different sources (view- and scan-based). Some results for the 
fusion of information arising from different laser devices is 
performed thanks to the flexibility of Polyworks. A particular 
case of this fusion is illustrated with the following hybrid 
example where excavated sepulchres and chapel structures have 
been scanned for a multirresolution model with several 
resolutions and two scanners (Minolta 910 and Ilris 3D, 
Optech). 
Figure 8: A partial view of the 3d model of the San Pedro 
Chapel in the monastery of Valbuena de Duero (Valladolid). 
In this case, one can not expect simple volumetric primitives 
enclosing the objects. Surveying of objects require the 
adaptation of more flexible tools such those related to the 
automatic isosurface extraction [Cignoni et al, 2005]. This 
adaptation is a goal research, and in the near future must allow a 
more adaptive behaviour to the objects, independently of curved 
surfaces appearing in their boundaries. 
6. CONCLUSIONS AND FUTURE WORK 
In this work we present a range scanning approach for 
surveying architectural elements with archaeological vestiges. 
Main technical advantages of laser scan approaches are linked 
to the simplicity of use, the low human cost, and the global 
metric information of scanned sites. All these advantages allow 
to achieve a high productivity for generating and managing a 
global 3d model, supporting metric information with several 
levels of detail on a 3d model which can be validated for future 
reference or easily updated for tracking. The adopted hybrid 
methodology involves to a) the use of two laser scans for 
capturing and inserting fine information in large 3d models and 
b) the design of algorithms for volumetric interpretation of 
irregular data in terms of simplicial 3d decompositions. Next 
steps to be done affect to the design and efficient 
implementation of efficient software tools, for rendering and 
interactive visualization in a low-level Augmented Reality 
module. In this way, we hope to increase the remote 
accessibility to Cultural Heritage sites with archaeological and 
historical contents. 
REFERENCES 
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Berg, M.; Kreveld, M.; Overmars, M.; Schwarzkopf, O.: 
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Cignoni, P.; Montani, C.; Scopingo, R. and Puppo, E.: Optimal 
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