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二维图形最狭长包络矩形的求解原理及方法

  

  • 出版日期:2013-08-30 发布日期:2015-06-18

The Solution to Determine the Bounding Rectangle with Maximum Aspect Ratio for 2D Graphics

  • Online:2013-08-30 Published:2015-06-18

摘要: :最狭长包络矩形是二维图形的一个潜在几何属性,可作为平面外形智能设
计、板料优化排样及图像自动识别的重要依据。目前国内外尚无此课题的专门深入研究。提
出了最狭长包络矩形的概念,将任意二维图形的最狭长包络矩形的求解转化为对其凸包的最
狭长包络矩形的求解。明确给出了过凸包上给定4 个顶点的包络矩形的包络角及长宽比求解
公式,并通过分析包络角及长宽比求解公式之间的关系,证明了凸多边形至少存在一条边与
其最狭长包络矩形的一条边共线。基于该定理,求解并比较与二维图形的凸包的n 条边分别
共线的n 个包络矩形的长宽比,得到了二维图形的最狭长包络矩形。最后用实例验证了定理
和求解方法的正确性和应用效率。

关键词: 计算几何, 最狭长包络矩形, 长宽比, 飞机样板设计

Abstract: The bounding rectangle with maximum aspect ratio is a potential property of 2D
graphics. This plays important roles in applications including the intelligent design of plane
geometry, certain packing and optimum layout problems, as well as pattern recognition. However,
no previous research is known for the problem. In this paper, a solution based on the convex hull
of the given graphics is proposed to determine it. By analyzing the formulae for the maximum
aspect ratio and the rotation range of the rectangle on which four given vertexes of the polygon
are, one significant theorem is introduced and proved to show that one side of the
maximum-aspect-ratio enclosing rectangle must be collinear with an edge of the enclosed
polygon. According to this theorem, we determine the target rectangle by computing and then
comparing the aspect ratios of n bounding rectangles which respectively have a side being
collinear with different edge of the graphics’ convex hull with n edges. The experimental results
are showed to prove that the solution is both accurate and efficient.

Key words: computational geometry, bounding rectangle, aspect ratio, aircraft template
design