An approach for multi-patch surface modification with a curve constraint satisfying convergent G1 continuity

Conceptual shape design plays a critical role in determining the appearance and functionality of a product. Currently, computer-aided design systems can represent a complex shape through multiple surface patches; however, the methods used for multi-patch surface modification are still limited and counterintuitive. There is an ongoing need for more intuitive and efficient surface modification tools that allow designers to directly control shape changes through specific constraints while maintaining surface quality. In this paper, we propose an intuitive modification approach based on the designer's activity to interactively manipulate a multi-patch surface with an arbitrary curve constraint with tangent continuity (G(1)) across connected B-spline patches. The advantages of the curve and surface superposition were used to change the shape of the surface. The first step was a shape-control mechanism that used shape functions to control the deformation of a superposed surface. A fine-tuning step was followed to ensure the aesthetic requirements and quality of the surface by achieving convergent G(1) continuity in a linear manner. The efficiency and practicality of the proposed approach have been verified using application examples. The proposed approach can be applied to modify surfaces used in the design of a complex geometric model.