摘要
在用模式引导(或CSG)方法对平面三视图进行三维模型重建时,首先须识别出平面视图的环路。提出了一个实用的提取平面视图中所有环路的算法和相应的实例。该算法的特点是,1)通过将平面与圆柱面相切时产生的平滑过渡断头线延长直至与最近的可见轮廓线(实线)相交的方式处理平滑断头线;2)通过先合并再分解的方式唯一地处理直线、圆和圆弧;3)把环路分成外环路和内环路,通过递归方式在平面视图中搜索所有外环路和在每个外环路中的所有内环路。有了上述特点,该算法能以统一的方式完整地提取出平面正交视图中所有存在的外环路和内环路。该算法已被编制成能在Auto CAD图形系统中使用的程序,并在多个平面正交视图实例中成功地提取出了所有存在的环路。
In 3D solid reconstruction from orthographic views by Constructive Solid Geometry（CSG）, one of the original parts is to recognize the loops from planar orthographic views. A practical algorithm and example for extracting all loops from planar orthographic views was proposed. The algorithm has following features： 1） for breaking end lines which will appear in the intersecting place between planar objects and circular objects, the algorithm treats it by extending it until it contacts other lines; 2） the algorithm can recognize lines, circles and arcs with unique results by first merging them and then breaking them in all intersecting point; 3） for loops is divided into the outer loops and inner loops, the outer loops is found out by searching objects recurrently and inner loops is found out by searching the outer loops recurrently. Therefore, the algorithm can extract all outer and inner loops with unified way in planar orthographic views. The program according to this algorithm which can be used in Auto CAD system has been made and it has found out all loops existed in some examples.
出处
《上海第二工业大学学报》
2006年第2期92-98,共7页
Journal of Shanghai Polytechnic University
关键词
三维重建
平面视图
提取环路
3D reconstruction
orthographic views
extracting loops
