保持柱状体特征的三维CAD模型直接编辑方法

A Direct Modeling Method for 3D CAD Models Preserving Columnar Features

针对传统的三维CAD模型编辑通常会改变模型的拓扑信息且依赖于建模特征信息问题,提出一种保持柱状体特征的三维CAD模型直接编辑方法.该方法依据边界表示模型构建柱状体特征,将编辑操作在柱状体特征内传播,自动修改关联的几何元素,保持柱状体拓扑不变,从而支持符合设计意图的高效编辑.主要定义了一种基于边界表示的柱状体特征,将点、边和面的直接编辑操作映射为对特征面元素的编辑;设计了一套面向柱状体特征的约束传播算法,通过约束求解判定编辑操作的有效性,求解需要改动的相关点、边和面,对模型更改符合用户意图.最后基于开源CAD引擎Open CASCADE(OCC),对正六棱台、电路板模型等进行了实验,证明了方法的有效性.

Aiming at the problem that traditional 3D CAD model editing often changes the topology information of models and relies on modeling feature information,this paper proposes a direct modeling method for CAD models that preserves columnar body features.This method builds columnar body features based on boundary representation(B-Rep),propagates editing operations within the columnar body features,modifies associated geometric elements while maintaining the topology.The method mainly includes defining a columnar body feature based on B-Rep,which maps direct modeling operations for points,edges,and faces to editing the surface elements of the feature;providing a constraint propagation algorithm for columnar body features,which determines the effectiveness of editing operations through constraint solving and meets user intent.Based on the open source CAD engine Open CASCADE(OCC),an experimental verification is conducted on hexagonal frustums,circuit board models,etc.,which proves the effectiveness of the method.