Effective Curve And Surface Modeling Of Automobile Shape For Creative Design

As people are requiring higher and higher diversity of product requirements, and the competition of automobile market is growing, companies are forced to significantly shorten the development cycle of the car body styling, produced more rich and varied car models, enhance innovation capability; on the other hand, computer-aided design software is playing a more and more prominent role in the design of the body, integration and digitalization are becoming the future development trend of car appearance design. Therefore, how to quickly achieve the design intent of automotive stylists, data-driven and knowledge-driven automotive body modeling, as well as three-dimensional modeling of data reuse issues need to be resolved.For effective surface modeling for automotive exterior styling, characteristics lines of car styling and shape space for exploration are analyzed, and then we propose a series of parametric templates with consistent topological structure for cars, including three dimensional view wireframe models composed of characteristic curves,3D parametric curve wireframes and corresponding surface models. By analyzing the types of carbody types and different surface generation types, three-dimensional part-based curve network is generated. After suitable post-processing and fairness treatment, we obtain high-quality three-dimensional curve-net for surface generation. Utilizing three different types surface generation method, including surfaces through quadrilateral curve mesh, N-side surfaces, trimmed surfaces with edge constraints, and the smoothing surfaces model of car shape can be automatically generated.The research work of this paper mainly from the following aspects:(1) Two-dimensional modeling of characteristic lines. Define more complete views of the two-dimensional car characteristics lines, the front, the rear, the side and the top, and achieve the consistency parameters between different models.2D body feature lines are extracted using program developed by our research group, and the establishment of2D characteristic data model library, is prepared for the modeling of3D curve body follow-up data, which can effectively realize the reuse of digital model.(2) Three-dimensional modeling of characteristic lines. By analyzing the projective geometry relationship of characteristic between four views of a car body, correspondences between3D curve body and different views of2D feature line are detected with statistician, finally, the three dimensional modeling of car body curve can be achieved; Optimize the3D body curve reconstructed and establish the data model library of3D body curve grid, which prepared data for3D surface modeling followed, and can effectively realize the data reuse of three-dimensional curve model.(3) Three-dimensional body surface. Different models contain different parts, similar different body surfaces. In this paper, according to the number of doors, windows and some other characteristics, we classify the models to six templates for different models. With the different surfaces generating method we defined, and the existing grid, the body surface modeling can be efficiently generated.Finally, using several examples to validate and analysis the3D surface modeling method proposed in this paper, the feasibility and reliability of the method are presented. Numerical examples show that the proposed method can automatically generate high-quality car body surface. We also established a labeled database for automotive styling based on our method for effective data reuse.