Abstract: To improve the display efficiency in the mobile terminal and the display accuracy of model detail, this paper proposes a novel algorithm for 3D CAD model patch generation based on type hierarchy and object graph element. By extracting the database information such as the type and shape attributes of models, 3D CAD models are represented by shape classification tree. The scale coefficient is estimated by 0-1 normalization method for classification tree node of interactive selection. After estimating the scale coefficient, the display accuracy of the model is confirmed and 3D CAD model patch is generated. Finally, this paper proposes a 3D CAD model display system in mobile terminal, and carries out the experiments on 3D CAD model patch generation. The experimental results prove the feasibility and effectiveness of this 3D CAD model patch generation method.

Key words: mobile terminal, 3D CAD model, patch generation, classification tree, scale coefficient

摘要： 为提高三维CAD模型在移动终端的显示效率，提高模型细节的显示精度，提出了一种基于类型层次结构及对象体元的三维CAD模型面片生成方法。依据模型的数据库表示形式，抽取其必要的类型和图形信息，将三维CAD模型用图形分类树表示；对交互选择的分类树节点，使用基于离差标准化的方法估算所选节点的模型规模系数；依据规模系数确定模型的显示精度，以此进行三维CAD模型面片的生成。在移动终端开发了三维CAD显示系统并进行了三维CAD模型面片生成实验，通过实验证明了所提三维CAD模型面片生成方法的可行性和有效性。

关键词: 移动终端, 三维CAD模型, 面片生成, 分类树, 规模系数