Development of Intuitive Shape Deformation Inerface for 3-D CAD

1．提出了一种以可变形物体为输入工具的直接、直观的界面概念，用于计算机中几何模型的3D形状操作。2．采用高弹性模量橡胶块嵌入低弹性模量聚氨酯泡沫块表面的应变片点阵设计了一种测量大范围变形的输入工具。 3．通过基于自由变形方法将输入工具变形映射到几何模型，即使使用简单形状（例如立方体）输入工具，也可以实现各种类型的变形。4.通过引入电磁3D空间传感器，可以直接直观地输入3D空间中的位置和方向以及形状变形。此外，脚踏开关使界面用户能够控制系统，例如，改变操作模式，同时用双手操纵输入工具。5.引入了指定几何模型的可修改/固定部分的功能，以便在使其他感兴趣部分变形的同时可以保留形状的一些完整和重要的部分。此外，接口系统与其他CAD（计算机辅助设计）系统之间的几何数据交换是通过IGES（初始图形交换规范）格式文件实现的。6.上述功能被纳入直接直观的3D形状操作接口系统原型中。使用该系统进行的一些实验得出以下结论：（1）所提出的概念和实现的原型系统可以实现各种类型的 3-D 形状变形，以及（2）虽然界面本身很难进行数值精确操作，但可以通过交换几何数据并使用传统 CAD 系统进行此类操作来解决该问题。

1. A oncept of direct and intuitive interface using deformable objects as input tools was proposed for 3-D shape operation on geometric model in a computer.2. An input tool to measure large-scale deformation was devised by adopting the lattice of strain gauges on the surface of rubber block with high elasticity modulus embedded in polyurethane-foam block with low elasticity modulus.3. Various types of deformation was enabled even with a simple shaped, e.g., cubical, input tool by mapping input tool deformation to geometric model based on free-form defomation approach.4.Direct and intuitive input of position and orientation in 3-D space as well as shape deformation was enabled by introducing electromagnetic 3-D space sensor. Also, a foot switch enabled a user of the interface to control the system, e.g., to change operation modes, while manipulating the input tool by both hands.5.Functionaliy for specifying modifiable/fixed portions of the geometric model was introduced so that some completed and important portions of the shape could be maintained while deforming other portion of interest. Also, geometry data exchange between the interface system and other CAD (computer-aided design) systems was realized through IGES (Initial Graphics Exchange Specification) format files.6.The features mentioned above were incorporated into a prototype of direct and intuitive interface system for 3-D shape operation. Some experiments using the system leads to the following conclusions : (1) various types of 3-D shape deformation are possible with the proposed concept and the implemented prototype system, and (2) though numerically precise operations is difficult with the interface itself, the problem may be solved by exchanging geometric data and using conventional CAD system for such operations.