Geometric Graphs to Study Ceramic Decoration

Abstract : As with geography, ceramic decorations are essentially spatial organisations of features. Therefore, they should be analysed with spatial indexes. But spatial analyses, at the shard or the complete ceramic scale, are often difficult to set up, mostly because of the contiguity of graphical features. This paper presents a new method to record and analyse ceramic decoration. We use graph theory, with a GIS interface and Python programming, to analyse ceramic decoration in a bottom-up process. A priori definitions are minimal and only concern elementary units (morphological, graphical and plastic) which compose the ceramic. The studied corpus is composed of ceramic decorations belonging to the Mailhac I facies (Late Bronze Age), characterised by complex figurative compositions. Each decoration — complete or fragmented — is considered as a spatialized network (i.e. geometric graph). Graph theory provides tools to record and measure proximities between units and normalised indexes to compare different decorations, whatever their completeness. The GIS offers a graphic interface and ensures the correctness of spatial relationships between these units. The typology of these units is realised in a hierarchical oriented graph. This structure allows processes of generalisation (going up the tree) and specification (going down the tree), permitting comparison between units with different kinds of resolution and/or complexity. The method presented here can be used for other types of mediums (statuary, rock art, etc.).