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Drap, Pierre 
A STONE-BY-STONE PHOTOGRAMMETRIC SURVEY USING ARCHITECTURAL 
KNOWLEDGE FORMALISED ON THE ARPENTEUR PHOTOGRAMMETRIC WORKSTATION. 
Pierre DRAP, Gilles GAILLARD’, Pierre GRUSSENMEYER",, Andreas HARTMANN-VIRNICH 
* MAP-GAMSAU umr CNRS 694, Ecole d'Architecture, Marseille, France 
Pierre. Drap@gamsau.archi. fr 
Gilles.Gaillard(@gamsau.archi.fr 
** ENSAIS-LERGEC, Photogrammetry and Geomatics Group, Strasbourg, France 
Pierre.Grussenmeyer@)ensais.u-strasbg. fr 
**+* LAMM, umr CNRS 6572 
hartmann@mmsh.univ-aix.fr 
Working Group WG V / 5 
KEY WORDS: architectural photogrammetry, stone-by-stone survey, knowledge representation, architectural 
archaeology . 
ABSTRACT 
ARPENTEUR is a web application for digital photogrammetry mainly dedicated to architecture (Architectural 
PhotogrammEtry Network Tool for EdUcation and Research) available at http ://www.arpenteur.net. ARPENTEUR has 
been developed by two complementary research teams: the "Photogrammetry and Geomatics" group of ENSAIS- 
LERGECS laboratory (Strasbourg, France) and the Gamsau-MAP CNRS laboratory located in the school of 
Architecture of Marseilles (France). 
This paper focuses on a new approach of stone-by-stone surveying in which formalised architectural knowledge is used 
as a prerequisite to the photogrammetric measurement process. 
In addition to this morphological definition, the structure point of view is implemented in the model in order to consider 
some architectural elements as containing a set of ashlar blocks. In our approach of stone-by-stone surveying, which has 
been conceived for the study of historical ashlar masonry but can be applied to other types of investigation, the 
measurement is performed directly on each individual stone in its built context. A previous edifice analysis , conducted 
by an archaeologist, is necessary to define the construction characteristics and chronology, and the properties of all the 
measured architectural entities. This results in the definition of an approximate depth for each type of stone, allowing a 
limited survey to the blocks visible part. An extrusion vector is computed in order to inform lacking geometrical 
description of the block. 
Once the instanced block is measured a polyhedron representation of its morphology is generated. The instance is also 
added to a data structure in which it is positioned according to topological or geometrical order. The result is therefore a 
collection of ordered blocks that includes, for instance, for each block data on its neighbours (adjacent blocks). When 
completed, the tool will create a direct link between the architectural object and the database, enabling to locate and 
thus identify the properties of each block registered in the database. The possibilities of this new type of approach to 
architecture extend from archaeology to restoration and maintenance to any type of structure treated by 
photogrammetrical survey. 
Retrieving architectural information (for example the intrados radius of an arch) is the approach we have developed in 
architectural surveying. We are currently working on giving this possibility in the stone-by-stone surveying process on 
which this paper focuses. 
1 INTRODUCTION 
1.1 Architectural survey 
ARPENTEUR is a web tool dedicated to architectural survey. It has the benefit of the two partner laboratories' 
expertise in the field of close range photogrammetry and architectural knowledge representation in a survey process. 
This collaboration is enriching for both researchers and students working on the project. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 187