LSIS, Laboratoire des Sciences de l'Information et des Systèmes

The paper presents an interdisciplinary project which is a work in progress towards a 3D Geographical Information System (GIS) dedicated to Cultural Heritage with a specific focus application on the Castle of Shawbak, also known as the “Crac de Montréal”, one of the best preserved rural medieval settlements in the entire Middle East. We develop a set of tools for medieval archaeological analysis ranging from the production of traditional graphical documentation like orthophotos and low-resolution 3D models (VRML) to the use of 3D/2D GIS through the creation of centralized and exhaustive object storage tool both for archaeological and photogrammetric data. Using these tools archaeologists will be able to produce, store, visualize and manage both archaeological and 3D data, according to their needs. The Shawbak archaeological project is a specific and integrated project between medieval archaeological research, conservative restoration and site's valorization. Focusing mainly on stratigraphical analysis of upstanding structures provides archaeologists with a huge amount of data to collect on site and useful records that will be used to understand the structures from stratigraphical and technological point of views. The foundation stone for this project is the analysis of documents produced and used by archaeologists in order to identify specific archaeological requirements The first phase is to give archaeologists traditional photogrammetric tools so that they can be autonomous in producing graphical documents (taking photographs, photo orientation and traditional orthophoto generation). The second step is to develop a common model structure for both photogrammetric and archaeological data storage using a unique database and allowing to link archaeological data with 3D measurements. Specific photogrammetry tools dedicated to stone by stone measurement have been under development since 2000 to help archaeologists to easily produce photogrammetric surveys. These tools are now integrated in a more complex system which allows automatic production of 2D or 3D representations from archaeological database queries. The graphical 2D documents produced through this process look like the handmade drawings done by archaeologists using orthophotos. The 3D GIS is the last step of this chain and aims the automatic production of 3D models through archaeological database queries: these 3D models are in fact a graphical image of the database and at the same time the interface through which the user is able to modify it. This approach enables automatic 3D thematic representation and new archaeological analysis through bidirectional-links between 3D representation and archaeological data. All these developments are written in Java within Arpenteur framework. (Arpenteur, 2008)

ROV 3D project aims at developing innovative tools which link underwater photogrammetry and acoustic measurements from an active underwater sensor. The results will be 3D high resolution surveys of underwater sites. The new means and methods developed aim at reducing the investigation time in situ, and proposing comprehensive and non-intrusive measurement tools for the studied environment.
In this paper, we are presenting a new method of 3D surveys which are dedicated to high resolution modeling of underwater sites. The main met constraints in situ are taken into account and this method leads to a precise 3D reconstruction. Some examples will present both the main obtained results and their limitations. We will end with the perspectives and the necessary improvements to the method, so as to automate the multimodal registration step.

This paper describes the ongoing developments in Photogrammetry and Mixed Reality for the Venus European
project (Virtual ExploratioN of Underwater Sites, http://www.venus-project.eu). The main goal of the project is to
provide archaeologists and the general public with virtual and augmented reality tools for exploring and studying
deep underwater archaeological sites out of reach of divers. These sites have to be reconstructed in terms of
environment (seabed) and content (artifacts) by performing bathymetric and photogrammetric surveys on the real
site and matching points between geolocalized pictures. The base idea behind using Mixed Reality techniques
is to offer archaeologists and general public new insights on the reconstructed archaeological sites allowing
archaeologists to study directly from within the virtual site and allowing the general public to immersively explore
a realistic reconstruction of the sites. Both activities are based on the same VR engine but drastically differ in
the way they present information. General public activities emphasize the visually and auditory realistic aspect
of the reconstruction while archaeologists activities emphasize functional aspects focused on the cargo study
rather than realism which leads to the development of two parallel VR demonstrators. This paper will focus on
several key points developed for the reconstruction process as well as both VR demonstrators (archaeological and
general public) issues. The first developed key point concerns the densification of seabed points obtained through
photogrammetry in order to obtain high quality terrain reproduction. The second point concerns the development
of the Virtual and Augmented Reality (VR/AR) demonstrators for archaeologists designed to exploit the results of
the photogrammetric reconstruction. And the third point concerns the development of the VR demonstrator for
general public aimed at creating awareness of both the artifacts that were found and of the process with which
they were discovered by recreating the dive process from ship to seabed.

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 ENSAISLERGEC’s
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.

ROV 3D project aims at developing innovative tools which link underwater photogrammetry and acoustic measurements from an active underwater sensor. The results will be 3D high resolution surveys of underwater sites. The new means and methods developed aim at reducing the investigation time in situ, and proposing comprehensive and non-intrusive measurement tools for the studied environment.
In this paper, we apply a pre-processing pipe line to increase the SIFT and SURF descriptors extraction quality in order to solve the problem of surveying an underwater archaeological wreck in a very high condition of turbidity. We work in the Rhodano river, in south of France on a roman wreck with 20 centimeters visibility. Under these conditions a standard process is not efficient and water turbidity is a real obstacle to feature extraction. Nevertheless the mission was not dedicated to an exhaustive survey of the wreck, but only a test to show and evaluate the feasibility.
The results are positive even if the main problem seems now to be the time processing, indeed the poor visibility increase drastically the number of photographs

The paper presents an interdisciplinary project which is a work in
progress towards a 3D Geographical Information System (GIS) dedicated to
Cultural Heritage with a specific focus application on the Castle of Shawbak,
one of the best preserved rural medieval settlements in the entire Middle East).
The Shawbak archaeological project is a specific and integrated project between
medieval archaeological research and computer vision done thanks to a long
cooperation between University of Florence and CNRS, LSIS, Marseille.
Focusing mainly on stratigraphical analysis of upstanding structures we provide
archaeologists with two-step pipeline. First a survey process using
photogrammetry, both in a traditional way with additional annotations and
using the most advanced technique to obtain dense maps and then a tool for
statistical analysis. Two main applications are presented here, stratigraphy
analysis with Harris matrix computed on the fly from the 3D viewer and
statistical tools, clustering operation on ashlar in order to show new
relationships between the measured artifacts.
All these developments are written in Java within Arpenteur framework[

San Domenico Church (Prato, Tuscan, Italy) is a very peculiar case of terrestrial archaeology surveyed with underwater archaeological photogrammetric approach. The vault of the choir was completely filled by a very important numbers of potteries, which is very interesting building technique. To document this technique a complete photogrammetric survey was realized, layer by layer, following underwater archaeology system. It is interesting to note that in underwater archaeology such a case is quite rare, in fact or the wreck is in shallow water and the digging can be made (but this case is now unrealistic because in shallow water all the wreck have been stolen – or already excavated by archaeologist - !) or we are in deep water, with well conserved wreck but the depth doesn’t allow the excavation. In the last case only a surface survey is possible. Also for these reasons this particular case- study is very interesting in order to test underwater methods on real case. This experimentation is a good opportunity to develop and check methods, algorithm and software to obtain a relevant model of the site merging 3D measure and knowledge about the artefact as typology, theoretical model, spatial relationship between them. Even if this work started in 2006, with now obsolete digital camera and with a photographic campaign which not respect always the current constraints for building a dense cloud of point in photogrammetry,it is now used as a case-study for developing a relevant approach for underwater archaeology survey.

The acquisition and processing of 3D data for the documentation of cultural heritage objects is a task gaining more and more importance nowadays. 3D models do not serve only as a valuable means for visualization and presentation of objects, but also represent a form of digital preservation and can additionally serve as a basis for archaeological or architectural analysis. The two NEWTONs IMODELASER and UPGRADE deal with this task by developing practices and tools for efficient data gathering and 3D documentation. While IMODELASER aims to optimize terrestrial image-based D modelling by means of integrating terrestrial laser scan data, e.g. of buildings or other medium scale objects, UPGRADE concentrates on data gathering and representation of underwater sites. In EPOCH Work Package 3, after identification of missing tools in the processing pipeline, various "New Tools Needed" (NEWTONS) were defined to be developed and implemented. Two of these tools, UPGRADE and IMODELASER, deal with 3D data acquisition by means of combinations of different types of sensors and under differ- ent environmental conditions. IMODELASER concentrates on 3D modeling based on terrestrial images and laser scanning, aiming for an optimization of the obtained models by exploiting the strengths of both sensor types in order to overcome their specific weaknesses. These are mainly the weakness of automatic image matching tech- niques when dealing with homogeneously or repetitively textured surfaces and the inaccuracy of laser scan point clouds in terms of edge modeling. Therefore, in IMODELASER we aim for a combi- nation of edges measured in images and highly dense point clouds for homogeneous surfaces yielded by laser scanning.