Development of 3D modeling system based on sketch

Three-dimensional Computer-Aided Design (CAD) systems have an extraordinary, form definition function which contributes much, such as streamlining, to the conceptual phase of the design process. However, when a user tries to develop his ideas by using the 3D Computer-Aided Design systems in the early stage of the design process, transferring some ideas may be limited because 3D Computer-Aided Design systems are built on the premise of accurate form definition. In addition, since 3D Computer-Aided Design systems are difficult to master, the requirement for highly skilled users is another issue that needs to be addressed. Indeed, designers usually convert their ideas into tangible forms by first drawing rough sketches. Therefore, if constructing 3D models from a rough sketch can be automated, it would help designers not only to realize their ideas, but to do it more efficiently. This paper discusses an interface system which is effective in the conceptual phase of the design process. This system recognizes primitives-cylinders, cones, spheres, and cuboids-from sketches of functional components drawn by the designer and then constructs 3D models. The system and the algorithm proposed here deal with the designing of functional components, so that 3D models are based on combinations of primitives. The system can build 3D models by the sketches drawn on a pen tablet. Input lines are approximated as straight lines or ellipses. The primitives which the designer intended are decided by the numbers of straight lines and ellipses.. The system has a function that can divide the information of the sketch lines of each primitive into layers to recognize multiple primitives. Experimental results show that the recognition of the primitives can be done correctly, and the implementation of the system in a 3D Computer-Aided Design system can further shorten the design time.