Study On The Realization Of 3D Automotive Styling Based On Sketching

The procedure of the automotive styling is actually a complex process which begins from 2D sketch to 3D model (or clay model). However, at present time, there is a gap between 2D and 3D in the CAS/CAD technology. It means that the stylists can not get the 3D model through putting 2D sketches into 3D designing software directly, and can not sketch freely in 3D CAD system as drawing on the paper. In addition, the creative design is discontinuous for stylists. As we know, the professional CAS engineers are responsible currently for creating the 3D models in the automotive styling. They are good at creating 3D models, but they are not stylists. They may misunderstand the stylists'ideas and modify the models again and again. The design process is slow and much of time has been wasted. As a result, to improve the design, the way that stylists create 3D model directly and easily like drawing through pen and paper is attracting a lot of attention.In this paper, a novel 3D sketching reference system for the automotive styling has been presented, based on the traditional means of sketching. It includes the datum plane, grid, wheels and work plane. After that, the transformation from 2D point to 3D point has been explained in the view of graphics and two methods for drawing curves in 3D have been investigated. At last, the novel realization methods for surface creating have been proposed and realized by programming, which is based on the traditional way of surface construction in CAD systems.The function of 3D sketching reference system is that making the stylists much freer and assisting them in sketching like drawing by pen and paper.3D sketching reference system consists of the datum plane, grid, wheels and work plane. The datum plane, grid and wheels just make the stylists familiar with the 3D environment and help them in sketching like drawing on the paper. Further, as the platform of curves, the work plane is manipulated most frequently in design and it's very important. Inspired by the traditional sketching methods, the manipulation of work plane includes move, switch, size change and locating on the curve, which have been realized by programming and the corresponding algorithms have also been explained clearly in the paper.The curve drawn by the digital pen is composed of a certain amount of ordered points. Furthermore, the change between 2D sketching curve and 3D curve is a process from 2D screen point to 3D point. According to the graphic method in OpenGL, a commutation process of matrix has been presented, which includes the model transformation, projection conversion and viewport conversion. At the same time, the method how to create 3D curves through sketching has also been discussed here and two methods have been proposed. The methods are the projection and the intersection, which are proved by the theoretical methods of tracking, intersection and algebraic iteration.Based on the novel means,3D surface can be built by sketching in 3D, which is different from the manipulation based on WIMP (Windows, Icon, Menu, Pointer) in CAS/CAD systems. Specifically, by the contrast and analysis on the traditional way of surface creating in CAS/CAD systems, the paper has proposed a series of novel ways of surface construction and explained the corresponding algorithms, which include the filling, stretching, rotating scan, sweeping, skinning, splitting, connecting and fillet.The algorithms have been designed and realized based on the ThinkDesign system. Some hardware and software are adopted, such as the digital pen and screens, the API of ThinkDesign, MS VC++2005 and so on. In addition, because of that the 3D digital automotive model is made up of point, curve and surface, the related sketching methods have been designed and realized. Above all, as the most important part in the AutoSketch system which is also the most important academic achievement in this topic, the realization means of 3D automotive styling based on the traditional sketching are very useful for the development of CAS/CAD system. The AutoSketch has filled the gap seamlessly between the 2D sketching and 3D modeling. It is also very useful for enhancing the quality and efficiency of the creative design.