Highly Flexible and Intuitive Computer-Aided Design Modeling

计算机辅助设计(CAD)已经成为产品设计的主导工业实践。虽然相当健壮和通用，但目前的商业CAD软件使用的是严格的基于参数的建模方案。设计师必须学会遵循一种非常特殊的技术来创建和修改模型。设计师不是专注于塑造整体模型几何图形，而是通过指定各个几何特征的尺寸并约束特征间的关系来创建模型。诚然，这是一种创建CAD模型的强大方法，因为它确保了所创建模型的准确数字表示。然而，随着新技术的出现，已有数十年历史的CAD建模方案面临着跟上时代的巨大压力。具体地说，最新的3D激光扫描仪和3D相机可以轻松地从物理对象表面捕获海量数据点。这些3D数字化设备将极大地促进直接从物理对象创建复杂的CAD模型。近年来，虚拟现实或3D可视化技术也在迅速发展。带有3D用户界面的原型CAD站已经被披露，并得到了媒体的大量报道。这些先进的3D技术将继续推动CAD建模向高度灵活和直观的环境发展。遗憾的是，目前的基于参数的建模方案过于僵化，不能充分利用新的3D技术，已经成为拖累整体技术进步的因素。

Computer-Aided Design (CAD) has been the dominant industrial practice for product design. While reasonably robust and versatile, current commercial CAD software uses a rigid parameter-based modeling scheme. Designers have to learn to follow a very specific technique for model creation and modification. Rather than focusing on shaping the overall model geometry, designers create models by specifying dimensions to individual geometric features and constraining inter-feature relationships. This admittedly is a powerful method to create CAD models since it ensures accurate digital representation of the created model. However, as new technologies emerge, the decades-old CAD modeling scheme is under significant stress to keep up. Specifically, the latest 3D laser scanners and 3D cameras can easily capture massive data points from a physical object surface. These 3D digitizing devices would greatly facilitate direct creation of complex CAD models from physical objects. Virtual reality or 3D visualization technologies are also advancing rapidly in recent years. Prototype CAD stations with 3D user interfaces have already been disclosed and received much media coverage. These advanced 3D technologies will continue to power the evolution of CAD modeling into a highly flexible and intuitive environment. Unfortunately, the current parameter-based modeling scheme is too rigid to fully utilize the novel 3D technologies and has become a drag to the overall technological advancement.