Searching an engineering drawing database for user-specified shapes

We present a novel approach to the retrieval of engineering drawings based on the use of stochastic models. Engineering drawing databases can be searched intuitively by presenting sketches or shapes which represent details such as, for example, screws or holes in the drawings of mechanical parts. The query is represented by a pseudo 2D Hidden Markov Model (P2DHMM) which is surrounded by filler states. These filler states generate the remaining part of the engineering drawing apart from the query shape or sketch itself. Thus, our approach aims to retrieve those images containing certain details and also locates these details in the retrieved images, even in cases where the query shape is embedded in, for examplle, hatching or is connected to other parts in the drawing. The proposed technique achieves a good performance which is demonstrated by a number of query and retrieval examples.