Date Added: May 2009
This paper proposes CAD data mining technique to obtain semantic elements without prior knowledge about plans being designed. The method consists of two steps. The first step is to extract frequent spatial relations between figure elements in CAD data as clues to the semantic elements. These relations are modeled as topology graph and are analyzed by a graph mining method. In the second step, valid semantic elements are specified by eliminating geometrically unnecessary figure elements through inferring every affine transformation between sets of figure elements having the same frequent spatial structure. In the experiments, the proposed method could extract semantic elements like electrical symbols from floor plan data without prior knowledge about the symbols.