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Drap, Pierre 
  
Least square optimization can thus be helpful for the approach or the identification of an ideal form, i.e. the theoretical 
concept of this form In the case of a gothic pointed arch, for instance, relevant geometrical proportions can thus be 
determined and compared. Applied to more complex structures, the process can help to characterize and to comprehend 
deformations as being related either to the more or less exact or inexact realization of a project, or to statics. 
5.2 3D cad outputs 
The resulting architectural model, entities computed and measured ashlar blocs have a set a 3D writing method able to 
generate ASCII WRML file and binary design file for MicroStation cad software made by Bentley. We choose to 
generate binary design file for MicroStation instead of the widely used DXF file format because we can easily introduce 
non graphical data linked to the architectural element representation. Its now easy to establish a link between the 
architectural element and its MicroStation representation. 
  
  
  
  
Figure 7. Results outputs for Microstation, Bentley and VRML 2.0. 
6 CONCLUSIONS 
As regards architectural and archaeological analysis, two essential issues of ARPENTEUR are to be pointed out : the 
use of the tool for direct measuring structural elements, and the link to be established between the image and a database. 
This second feature is of particular interest, as it combines a representation of the architecture itself to the database 
serving as a tool for the analysis of its units. It will be in fact most useful to locate in or through the virtual image all the 
blocks of one same category, as defined and registered in the database files, such as : type of block (voussoir, 
cornerstone, column, capital... ) or architectural unit (window, buttress, vault, bay... ), type of stone, state of 
preservation, details of surface (mason marks... ). Spotting these categories in their architectural context offers the 
advantage of relevant groups clear perception . It is easy to imagine the wide range of possible applications, far beyond 
the domain of architecture and restoration. 
Mechanical simulation 
Beyond this work presented here this approach of the link between photogrammetric survey and architectural 
knowledge is the first step to another project dealing with a new approach for the mechanical modeling of historical 
monuments built with blocks. (Acary and all., 1999). The computational method, Non Smooth Contact Dynamics 
(NSCD), is used to simulate masonry as a large collection of bodies under unilateral constraints and frictional contact. 
The computational method, NSCD, within an architectural and archeological model are merged in a single tool 
providing a interdisciplinary approach of historical buildings where the presented work, a photogrammetrical survey 
monitored by an architectural and archeological knowledge, gives the buildings morphology and initial deformations. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 193