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

Traditional 3D CAD model editing often changes the topology information of models and relies on modeling feature information. Aiming at this problem, this paper proposes a direct modeling method for CAD models that preserves columnar body features. This method builds columnar body features on a CAD boundary representation model based on the information of points, edges, and faces to be edited, propagates editing operations within the columnar body features, automatically modifies associated geometric elements, and maintains the topology of the columnar body unchanged, thereby supporting efficient editing consistent with design intent. The main contributions of this paper include: 1) defining a columnar body feature based on boundary representation, which maps direct modeling operations for points, edges, and faces to editing the surface elements of the feature; 2) A constraint propagation algorithm for columnar body features is designed, which determines the effectiveness of editing operations through constraint solving, solves relevant points, edges, and faces that need to be modified, and makes model changes that meet user intent; 3) Based on the open source CAD engine Open CASCADE, an experimental verification of the proposed method is conducted, which proves the effectiveness of the method.