is an interface to the 
in the XML result 
  
.as the VRML one, 
/ generated after the 
XML result file 
  
1 Detail of the last 
ttom of the wreck 
of amphora. 
>s take advantage of 
of a default value 
easurements of the 
object by using jointly a group of measurements and the 
generic properties of the type of object studied. 
The project is presented on an Internet site 
(http://GrandRibaudF.drassm.gamsau.archi.fr) which 
offers at the same time a work interface for 
archaeologists and a presentation medium of the 
excavation for the public at large. Access to the 
archaeological data can be done using the VRML 
interface and in modification / adding mode by the text 
interface, protected by restricted access. 
3. MANAGING ARCHAEOLOGICAL DATA 
In the context of this project a lot of data are produced 
from various sources. Heterogeneity is one of the main 
problems of this kind of applications, it can be found at 
several levels from the data sources to the target format. 
We mainly focus on three kinds of heterogeneity due to 
(i) multiple data sources, (ii) differences between objects 
of study and (iii) changes between versions. The purpose 
of this section is to describe the troubles at data 
representation and manipulation level to introduce our 
data model. 
3.1 Heterogeneous data sources 
The first kind of heterogeneity comes from the 
differences between data sources. In our application, they 
can be divided in two main families whether they are 
calculated or produced by an expert. The first ones are 
often well structured (i.e. vector or matrices) whereas the 
second ones are less structured (natural language), we 
will call them semi-structured data, it is important that 
they can be more structured than full text. We are dealing 
with multimedia data, mainly pictures and semi- 
structured text. 
That is why the data model must provide a way to 
federate heterogeneous data across multiple data sources. 
The user must be provided with a unified view of data. 
3.2 Dealing with objects specificity 
The second kind of heterogeneity comes from the 
differences between studied objects, for instance between 
amphora and parts of amphora or even between amphorae 
themselves. Many data come from pictures, thus if not 
enough pictures are available, some pieces of information 
can be missing. Another problem comes from the fact 
that some object may be incomplete (i.e. broken 
amphorae). 
The data model must also provide tools to express 
variations between objects from the same class and 
different level of details in the description of an object. 
3.3 Temporal heterogeneity 
And last but not least, we have to deal with changes. The 
changes can take place at several levels from values to 
data structure. For instance, the values can change 
between underwater and surface measurements; this kind 
of changes can be managed with modern database 
systems. But in our application, the classification of data 
(i.e. relation between families of objects) and the inner 
structure of those objects depend on the knowledge of 
experts and this knowledge can change when new 
measures are done. The data model must provide an easy 
way to change the schema of data and application build on top 
of it must be able to deal with change. 
4. USING XML FOR MODELLING 
PHOTOGRAMMETRIC DATA 
For all the reasons presented in the previews section we have 
chosen XML as our data model. XML is the de facto standard 
for federation and exchange of data between heterogeneous 
applications. The purpose of this section is to present the main 
advantages of XML for the description, the manipulation and 
the presentation of multimedia data in the context of 
archaeological data. 
4.1 XML an adaptive data Model 
XML? is a recommendation of the World Wide Web 
consortium (W3C). XML language is designed to associate a 
tree structure to data. The tree structure is expressed in the data 
thanks to tags (an opening and a closing tag define an 
element). A set of attributes can be associated to each element. 
The content of an element can be either empty of composed of 
an ordered list of elements and texts. 
«?xml versions'1.0'?- 
«amphora» 
«generalAmphoraDescription 
subCllass="PY4-G1" 
type="Col" 
name="Col" 
localisation="surface" 
nbFrgmt="3" 
s 
<photographList> 
«referenceSystemIdentification 
name-"PhotoModeler"  /» 
«photograph 
num-"48" 
camera-"NikonCxHz.xml" 
file-" DSC 0022.JPG" 
X="-7403.72775" 
ys"917.997408" 
2="3531.9815/2" 
Omega="3.166408809545499" 
Phi="3.2035977616482154" 
Kappa="4.576008655927882" 
/> 
</photographList> 
<point3DList> 
«referenceSystemIdentification 
name="PhotoModeler" /> 
«point3D pt="OBSERV 1 -7403.728 917.997 
3531.982 "/> 
<point3D pt="F PER | -7174.666 833.136 
168.520 "/> 
</point3DList> 
«Remark» Is this some fragments of 
«amphoraRef ref-'29'/» 
</Remark> 
</amphora> 
Figure 4 shows a fragment of XML document, it describes an 
amphora. One can see that both numerical data 
(coordinates or 3D points) and textual data 
(Remark made by an expert) are expressed in the 
same XML document. 
  
? http://Wwww.w3.org/TR/REC-xml 
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