Last modified: 2011-12-18
Abstract
Medieval and modern fiscal documents (fieldbooks, compoix, cadasters ...) provide a rich information on spatial organization of the countryside. They usually describe each plot indicating the owner's name, the surface, the land-use, the neighbours and the location. These lists, which contain hundreds of plots with their relative location, have a great potential for analyzing the spatial pattern of village territories and the evolution of the landscape, especially when there is a series of successive documents for the same territory, as it is often the case. Nevertheless, they have been dramatically under-exploited because it is so difficult to reconstruct the landscape from fieldbooks without maps – and field-maps in France only appear in the 17th - 18th centuries. To overcome this difficulty, we suggest a model of former plots described in fiscal documents based on the use of graph theory. The framework is the ANR project Modelespace (http://w3.modele-espace.univ-tlse2.fr/). The aim is to measure the spatial dynamics between several states of the documentation related to the same territory.
The main idea is to transform the spatial information collected on one side from the register and on the other side from former plots’ plan into graphs. The translation of spatial data into graphs should allow to set up a bridge between the historical documents, mapped and not mapped. On these graphs each plot corresponds to a vertex and each neighborhood relationship (adjacency) - visible on a plan or described in the documents as neighbour - is an edge. The work is carried out along two complementary approaches: the first focuses on establishing a database dealing with records without map. The second aims at extracting the graph of former plots’ plan in a Geographic Information System. The goal is to match the graphs produced by these two approaches in order to analyze spatial change by comparing the graphs since plans or registers alone do not allow it.
Firstly, the transformation protocol of plots’ plan into graph in the GIS will be developed. The first step is the vectorization of plans according to a topological structure which allows the production of planar graphs of the plots. The second step is the extraction of the dual graph thanks to adjacency matrices.
Secondly, we will consider the possibilities of comparing two graphs corresponding to two successive states in the GIS .The first possibility of comparison is simply the exploitation of vertices’ attributes describing the parcels (land use, surface, owner) to measure continuities and discontinuities. The second possibility of comparison is related to the spatial transformations themselves. This is to demonstrate, from the graphs, parcels reconstructions at work, that is to say recognize in the transition from one graph to another, the space-time operators of relevant changes in the case of a parcel: creation, stability, expansion, contraction, deformation, fission, fusion. The difficulty lies in overcoming the static comparison of two states to move towards a dynamic representation. The adoption of a time graph would allow us to characterize specific changes.