Based On The Characteristics Of Two-dimensional Parametric System

With the advancement of technology for computer-aided design in 3-dimension space, and the availability of faster hardware/software platforms at a lower cost, computer-aided drafting in 2-dimension paper space sounds like an antiquated past, which is leaving us silently. But there are still problems confronting the deployment of full 3D design systems. For example, the training of users, who are already familiar with the design process based on 2D draftings, is proved to be a costly and sticky tack. In addition, the prospect of using 3D model as the communication media in real engineering environment still seems too far away from us. Due to the special engineering drawing conventions, the role of 2D drafting will not be completely repaced by drawings generated from 3D models in the foreseeable future. In this dissertation the author presents a technique which can bend the power of 3D design and the convenience of 2D drafting together, and hence provides a smooth transition way from 2D papers pace to 3D model space. This technique, based on the parametric design technique in 2D drafting and the feature-based design technique in 3D design, is a feature-based 2D parametric design method. With this technique, the designer can use 2D feature to construct engineering drawings in a 2D paper space environment, which he is familiar with, in accordance with the convention of engineering. While at the same time, the 3D design system engine, working under the coat of the 2D drafting interface, will construct a truly 3D feature based model automatically. The author gives the definition and representation of 2D feature. Then she describes the operations that can be performed on these 2D features, such as locating, assembling and modifying. In the implementation of this technique, the author presents a method of using Relation Database System(RDBS) to organize, store and manage the data of features. By means of eature tree?the representation and management of the feature-based model enables a direct access to every feature in the model.