3D模型的拾取在三维人机交互、交互式图像系统图形拾取方面均有重要应用, 目前普遍的拾取算法均需利用鼠标操作才能实现, 在拾取计算过程中常存在一系列矩阵求逆的问题, 且对 3D模型构造的拾取包围体过于单一, 影响拾取的有效性、便捷性和精确性。本文提出了一种基于空间方位向量与包围体策略结合的 3D模型拾取算法。首先, 用实体交互笔代替鼠标, 在下位机解算交互笔空间姿态信息, 将交互笔空间方位向量实时映射到虚拟场景世界坐标空间并生成一条拾取射线; 其次, 采用形状判定阈值策略, 对 3D模型不同模块的外形特征实时建立针对具体模块的盒状包围体和球状包围体; 最后, 通过拾取射线与具体包围体的相交检测, 判定是否拾取了具体模块。实验中以拾取具体 3D模型为例, 相比于经典射线与单一包围体的拾取方法, 本文所提出的算法对模块的拾取速度提高了 16.98%, 对 3D模型相邻模块边缘的拾取误判率从单一包围体的 71.26%降低到 12.80%, 操作便捷有效。

The pickup of 3D model is importantly applied in terms of 3D human-computer interaction, and the graphics pickup of interactive graphics system. Currently, the picking algorithm must count on mouse. There are a series of inverse matrix problems in the process of picking algorithm, such as too much simple pickup-surrounded of the structure of 3D model, which influence the effectiveness, convenience and veracity of pickup. A 3D model packing algorithm is presented based on spatial orientation vector and bounding volume strategy. Firstly, spatial attitude information of interactive pen is solved in the slave computer space using entity interactive pen instead of a mouse, then map it into the virtual scene space to make a pick-ray. Secondly, adopt the strategy of shape determination threshold, for 3D model, according to the shape characteristics of different modules, which establish box-shaped bounding and spherical bounding real-time. At last, we judge if it pickup the specific modules or not through the intersection detection between pick-ray and specific bounding. We make specific 3D Model as an example in our experiment, with the using of this algorithm which is pointed out in this paper, the rate of pickup rises 16.98%. What’s more, the pickup misdiagnosis rate of module edges of 3D model is lowed down to 12.80% from 71.26% when it uses the single bounding. The operation is effective and convenience.