【摘要】 为了弥补传统的基于属性检索方法的缺陷和不足,真正实现机械3维CAD模型基于几何内容的聚类和检索,提出了一种基于内容的机械3维CAD模型的聚类和检索方法。首先,基于查找关键字的方法,将CAD模型的产品模型数据交换标准AP203 Part21文件转换为属性图文件;其次,进行属性图的相关属性计算,提取特征不变量,并结合属性图的节点和边的相关属性形成CAD模型的特征不变矢量;最后,用特征不变矢量作为自组织特征映射神经网络的输入,利用其保拓扑性对CAD模型进行聚类分析。基于60种工业实用CAD模型对该方法进行了实验验证,结果表明,所提方法可行有效,能够满足一般工程检索的需要。更多还原

【Abstract】 To overcome the shortcomings of traditional attribute-based retrieval method and to realize geometrical-content-based retrieval for mechanical three-di mensional(3D) CAD models,a newapproach of clustering and re-trieval of mechanical 3D CAD models was presented.Firstly,The STandardfor the Exchange of Product model data(STEP) AP203 Part21 files of CAD model were transformedinto attributed-graph files by searching and matchingkeywords.Secondly,feature invariants were extracted and feature invariant vector of CAD model was formed bycalculating graph related attributes such as the total number of nodes and edges.Finally,a Self-Organization fea-ture Mapping(SOM) neural network model was employed to cluster and retrieve CAD models by using the extractedinvariant vector as its input to train the neural network.The proposed approach was verified to be valid and feasiblebased on 60 real industry 3D CAD models,and the experi mental results showed that it could meet general require-ments of engineering retrieval.更多还原