Three-dimensional Modeling For Car Styling From Engineering Drawings Or Single Views

The application of digital design technology has become one of the symbols of the development of automobile. Compared with traditional design, digital design has advantages in high efficiency, economy and reusability.3D digital model can well reflect the designer’s design intention and show body shape or molding style intuitively. Designers can also do some operations in digital model directly to short development cycle of the car body, such as modification, optimizing.In the stage of the body design, curves model is the foundation of surface modeling. The feature line is widely adopted as a model representation and is the link between styling designers. It is a key technology to effective transform2D design sketches into high-quality3D digital models in auto body concept design stage. For this problem, we adopt a reasonable scheme to definite the feature lines and put forward a3D reconstruction method based on the engineering drawing and another3D reconstruction method based on single view. Research work mainly includes the following three aspects:Firstly, this paper utilizes a consistent3D feature model with consistent topological structure for car styling and proposes a new curve fitting method based on least squares to recovery the3D curved digital model. In this method, we realize the rapid transformation of the2D feature line model and3D wire-frame model by matching the endpoint of2D feature lines and fitting the date get by discretizing the2D parametric curves. Besides, some continuous post-processing is applied in3D characteristic lines so as to ensure the fairness of3D digital model.Secondly, we provide a3D reconstruction method based on single view (side views) through the analysis of the existing3D reconstruction methods. This method is based on the3D model database and realized by building the minimum cost function with the mapping between2D data and current3D data to estimate the corresponding3D model data. Then a fitting based on the data of given single view is applied on the3D model again to get the new3D wire-frame model. The result shows that this method not only guarantees the depth information of the3D model but also meets the accuracy in the direction of the side views.Finally, we proved the feasibility and effectiveness of the algorithm in this paper by numerical experiments and error analysis. Numerical experiments show that the accuracy of 3D parametric model generated by the method based on the engineering drawing is above90%. The reconstruction result of the3D reconstruction method based on single view can meet the needs of body shapes. Our work gives a numerical support for the generation and reconstruction of surface model in the future.