Mesh models have been widely employed in current CAD/CAM systems, where the workpiece is considered as made up of a number of features limited by natural boundaries. The natural boundaries among features are in most cases edges where an abrupt change of point differential geometry properties occurs. However, such features and underlying surface portions could also be connected smoothly without an abrupt change at the natural boundaries. In the context of ISO GPS (Geometrical Product Specifications and Verification) Standards, partitioning is a fundamental operation that decomposes a mechanical part into independent surface portions for a functional specification purpose. In this paper, an enhanced mesh partitioning method is proposed to enable a feature-based decomposition considering kinematic invariance classes. The proposed two-step method includes an initial partitioning based on sharp edge detection and an enhanced partitioning process based on non-sharp edge rectification. The partitioning criteria rely on two surface descriptors derived from shapes’ principal curvatures: Curvedness and Shape Index. To refine the boundary points on non-sharp edges, conformal geometry is exploited during the enhanced partitioning process by mapping the 3D surface onto a 2D unit disk. Connecting regions without abrupt changes at their natural boundaries are well partitioned after the boundary rectification process. A statistical evaluation process is used to address invariance class identification for each partitioned surface portion on the part. Experiments and results on different mesh models are presented to demonstrate the effectiveness of invariance class partitioning for ISO GPS.

网格模型已广泛用于当前的CAD / CAM系统中，在该系统中，工件被认为是由受自然边界限制的许多特征组成的。在大多数情况下，特征之间的自然边界是发生点微分几何特性突然变化的边缘。但是，这样的特征和下面的表面部分也可以平滑地连接，而在自然边界处没有突变。在ISO GPS（几何产品规格和验证）标准的上下文中，分区是一项基本操作，该功能将机械零件分解为独立的表面部分以达到功能规格目的。在本文中，提出了一种增强的网格划分方法，以考虑运动学不变性类，实现基于特征的分解。所提出的两步方法包括基于锐利边缘检测的初始划分和基于非锐利边缘校正的增强划分过程。划分标准依赖于从形状的主曲率得出的两个表面描述符：“弯曲度”和“形状指数”。为了细化非锐利边缘上的边界点，在增强的分区过程中，通过将3D表面映射到2D单位磁盘上，利用了共形几何。在边界校正过程之后，在其自然边界处没有突然变化的连接区域将得到很好的划分。统计评估过程用于处理零件上每个已划分表面部分的不变性类别标识。