The Research & Application For Technology Of Engineering Drawing Information Encoding

Computer interpretation of engineering drawing is an intersectant subject of engineering graphics, computer graphics, cognitive science, information science and computer aided design. It will be a promise application in the area of CAD/CAM. However, it is clear that all the current relevant methods are far from the aim of practical application of computer interpretation. Based on the standpoint of quantification of drawing information, a new technology of engineering graphic information encoding is put forward in this thesis.In chapter 1, the history and development of engineering drawing interpretation are reviewed, at the same time the existing problems are analyzed and then the content of this thesis is introduced.In chapter 2, at first the classification of engineering semantics is introduced, which the information of drawings function as. Then by borrowing the ideas of the theory of self-information, drawing-information-degree is proposed, which approximately describe the information quantity of the drawing elements. Finally, according to classification of engineering semantics, the encoding rules of the drawing-information-degree are given respectively.In chapter 3, model-building technology of drawing information is mainly discussed. After the pre-processing, the graphic information and dimension information are organized based on the drawing-information-degree. As a result the organizing model of drwaing infornation of connected domain, dimension tree and dimension -restraining-graph chains are obtained.In chapter 4, the application of engineering drawing information encoding technology in 3D-Reconstruction is discussed. Firstly, the expression style of primitive is introduced. Secondly a computational model searching for "free graphc element " is given and based on this the strategy of the primitive relation recognition is proposed. At last it is also discussed that taking use of graphic and demension information to reconstruct primitives.In chapter 5, the prototype system of drawing interpretaton is developed, and some examples are given.In chapter 6, the work of this thesis is summarized, and the further research work is put forward.