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观界面概念，用于计算机对几何模型进行三维形状操作.采用在高弹性模量橡胶块表面嵌入低弹性模量聚氨酯泡沫块的应变片网格，设计了一种测量大变形的输入工具.即使使用简单的形状，也能够实现各种类型的变形，例如，通过引入电磁式三维空间传感器，实现了三维空间位置、姿态和形状变形的直观输入。此外，脚踏开关使得接口的用户能够控制系统，例如，5.引入了指定几何模型中可修改/固定部分的功能，使得形状中一些完整的重要部分可以保持，而其他感兴趣的部分可以变形。通过IGES（Initial Graphics Exchange Specification）格式文件实现了接口系统与其他CAD（Computer Aided Design）系统之间的几何数据交换。6.将上述功能集成到一个直观的三维形状操作接口系统原型中。使用该系统的一些实验导致以下结论：（1）各种类型的3-D形状变形是可能的所提出的概念和实现的原型系统，和（2）虽然数值精确的操作是困难的接口本身，这个问题可以通过交换几何数据和使用传统的CAD系统进行这样的操作来解决。

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.