The Research & Application Of Engineering Semantics Model For Engineering Drawing Interpretation

Engineering drawing intelligent interpretation is an intersectant subject of Computer Graphics and Computer Aided Design. For engineering drawing this dissertation formalizes the engineering semantics by divide and classify it, and establish a model of integrated network of engineering semantics. The model is applied to understanding 2D engineering drawing, extracting the deep information, obtaining 3D object.First, the research and relative subject on engineering drawing interpretation and feature recognition and object composing is summarized. The way of work is put forward.Second, the practical engineering drawing is analyzed and the model of integrated network of engineering semantics is established. According to the model, in respect of the content of engineering drawing the semantics is divided into the projection relation semantics, the expression mode semantics and the dimension constraint semantics. In respect of the deepness of information, the semantics is classified into the lower semantics, the middle semantics and the upper semantics. Furthermore the relation of the semantics is extracted. According to the model, all the engineering semantics is analyzed. These semantics lays a strong base for the 3D reconstruction and the engineering drawing understanding.Then, the features that describe 3D-entity are classified. The semantics is applied to engineering drawing interpretation by feature recognition. The application of semantics is discussed as follows: the projection relation semantics leading to recognizing cylinder, the region semantics leading to recognizing linear sweeping, the free element semantics leading to recognizing the feature which the cylinder is cut by plane.Last, a prototype system is developed according to the semantics model. The system can read dxf that contains 2D engineering drawing information and recognize the 3D feature.