Point cloud based design and manufacturing

传统的CAD/CAM软件使用简单的CSG块等基元结合布尔求交等操作来创建三维模型。雕刻的B-Spline曲线和曲面可以相加，并进行“求值”，以产生“B-rep”有界的体积封闭曲面的拓扑集。在实践中，CSG到B-REP的求值过程涉及不精确的曲面/曲面交点，基于浮点舍入的交换可靠性问题仍然存在。与此同时，立体视觉和激光三角测量系统，用于将设计概念模型等数字化成密集的点云，已被越来越多的人接受。这些点云被转换为拟合样条线曲面，并进行光顺，以平滑曲率“凹凸”。B样条线的使用降低了数据存储要求，并与现有的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.