Point cloud based design and manufacturing

传统的CAD/CAM软件采用简单的“CSG”块等原语结合布尔相交等操作来创建三维模型。雕刻的b样条曲线和曲面可以添加，并“评估”以产生“B-rep”有界的拓扑集，体积封闭曲面。实际上，CSG到B-rep的评估过程涉及不精确的面/面相交，并且基于浮点四舍五入的交换可靠性问题仍然存在。与此同时，用于将设计概念模型等数字化为密集点云的立体视觉和激光三角测量系统也得到了越来越多的认可。这些点云被转换为拟合的b样条表面，并被“平顺”以平滑曲率“凸起”。b样条的使用减少了数据存储需求，并且与现有的IGES/STEP交换标准兼容。

Conventional CAD/CAM software uses simple "CSG" block, etc. primitives combined with Boolean intersect, etc. operations to create 3-D models. Sculptured B-spline curves and surfaces can be added, and "evaluated" to yield a topological set of "B-rep" bounded, volume enclosing surfaces. In practice, the CSG to B-rep evaluation process involves inexact surface/surface intersections, and floating point round-off based exchange reliability problems remain. Concurrently, stereo vision and laser triangulation systems, used to digitize design concept models, etc. into dense point clouds, have grown in acceptance. These point clouds are converted to fitted B-spline surfaces and "faired" to smooth out curvature "bumps". Use of B-splines reduces data storage requirements, and is compatible with the existing IGES/STEP exchange standards.