共查询到19条相似文献,搜索用时 676 毫秒
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确定任意多边形的核的算法 总被引:6,自引:0,他引:6
本文提出确定任意简单多边形L的核的算法,该算法的时间复杂性是O(ln)次乘法,其中n是多边形的L的顶点数,l是多边形L中凹点的数目。 相似文献
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激光三维雕刻中扫描算法的研究 总被引:1,自引:0,他引:1
采用分层制造原理研究激光三维雕刻技术.在对现有激光扫描方式进行分析的基础上,从算法实现的难易程度、扫描效率及对硬件性能的要求等方面综合考虑,确定将直线扫描作为激光三维雕刻的扫描方式.给出了激光三维雕刻中直线扫描的原理,详述了扫描线生成算法并实现阴刻及阳刻扫描.针对直线扫描中存在的不足,提出并实现了一种新的直线扫描算法.应用结果表明,该算法稳定可靠、效率高,完全满足激光三维雕刻中的扫描需求. 相似文献
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对于给定的平面简单多边形顶点序列,判别多边形方向和顶点凸凹性的传统方法为:先计算多边形相邻边向量的叉积或相邻3个顶点所确定三角形的有向面积,再由叉积或有向面积的符号来确定顶点的凸凹性,使得处理一个顶点需要2次以上的乘法运算。笔者通过边向量斜率的计算和比较,将多边形顶点的凸凹性与边向量的斜率联系起来,并采用“假设-检验”方法,提出了一种快速判别简单多边形方向与顶点凸凹性的新算法,其时间复杂度为)(nO,判别多边形任一顶点凸凹性所需的乘法运算平均不超过1次。该算法原理直观简单,实现容易。实际运行结果表明,该算法速度快捷、运行稳定。 相似文献
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在2D图形引擎中,可见性判定是一个非常重要的问题.通过屏幕裁剪,可以进一步减少多边形数目,减轻引擎的负担.因此,在屏幕裁减阶段完成的屏幕顶点与多边形的内外关系判断就显得很重要了.文章结合2D图形引擎的特点和流行的内外点判别算法给出了在DirectX平台上使用VC++实现的平面多边形内外点判断算法,并将其应用于实际的2D图形引擎中.程序验证表明,该算法能有效判定屏幕顶点与多边形的内外关系,且算法效率较高、简单易行. 相似文献
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提出一个实际问题,即如何连接平面上h条线段成一简单多边形或者简单多边形链,并证明了连接平面上线段集S成一简单多边形链的一个充分条件,S中有一条线段连接凸壳CH(S)中不相邻顶点,另外还提出了连接平面上线段集S成一简单多边形或者简单多边形链的算法,其基本思想是首先逐层计算线段集S的凸壳,并将这些凸壳改变多边形;然后计算各多边形之间的交点,进而删去这些交点。最后合并若干个简单多边形为一个简单多边形,当S中线段数目n较大时,用分治思想可以设计分治算法,较好地求解了这个问题,利用计算机求解这个问题上有实际应用价值。 相似文献
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针对磁瓦生产过程中表面缺陷检测的重要性和人工检测的弊端,研究基于机器视觉的磁瓦表面缺陷自动检测与识别方法.为解决磁瓦表面缺陷种类多、对比度低、图像中存在磨痕纹理背景和整体亮度不均匀等难点,定义扫描线梯度,其标准差与扫描线灰度标准差构成特征向量,提出基于两类支持向量机的图像分割方法来判别和提取缺陷;并提出一种改进的多类支持向量机方法,对缺陷进行分类识别,解决了多类支持向量机存在不可分区域的问题,提高了分类器的准确性和有效性.实验结果表明,该方法能准确快速地提检测磁瓦表面各区域的各类缺陷,检出率可达到96%以上,识别率超过91%. 相似文献
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简单多边形集凸包的快速算法 总被引:3,自引:0,他引:3
提出了一个简单多边形集凸包的快速算法.先求出每个简单多边形的(子)凸包,根据凸包的切线性质,从有关的子凸包中抽取一段严格单调的折线.应用归并排序方法把位于一条直线右侧的一组严格单调的折线合并成一条折线,把合并后的折线和子凸包集的外接矩形上的边连结成一条封闭折线,即一个简单多边形,使其能够把所有子凸包包围起来,最后求出这个简单多边形的凸包.算法的时间复杂度为线性O(n),并且给出一个例子进行了验证. 相似文献
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The aim of this study was to calculate a reasonable correction factor that could be corrected when the sensitivity of each gamma camera is measured and a whole body bone scan is performed as a follow-up examination. Seven pieces of equipment were used to analyse the sensitivity measurements of each gamma camera based on the source sensitivity measurement method recommended by the IAEA. These were BRIGHTVIEW, PRECEDENCE, ECAM, ECAM signature, ECAM Plus, SYMBIA T2 and INFINIA. The 99mTc line source for the sensitivity measurement was generated in 4–7 kcps, which are the common values in a whole body bone scan. All the cameras were equipped with a low-energy and high-resolution parallel multi-hole collimator and set at a window width and photo peak of 15% and 140 keV, respectively. After placing the 99mTc source as closely as possible to the collimator, the count was measured for 60 and 120 seconds to calculate correction factor. To determine if the correction factor calculated using the 99mTc line source could be applied to a whole body bone scan of a real patient, a whole body bone scan was performed on 27 patients before applying the correction factor for comparative analysis. According to the experimental results using the 99mTc line source, the gamma camera sensitivity was the highest for ECAM plus, followed in order by the gamma cameras, ECAM signature, SYMBIA T2, ECAM, BRIGHTVIEW, INFINIA and PRECEDENCE. When the results were used to calculate the correction factor based on the ECAM gamma camera, which had a medium-degree of sensitivity, the respective correction factors were 1·07, 1·05, 1·03, 1·00, 0·90, 0·83 and 0·72. The correction factors calculated based on the experiment using a 99mTc line source were similar to those calculated based on the whole body bone scan. Clinical application of correction factor for measured sensitivity enables estimation of factor correction depending on difference in equipment when image is read, which improves accuracy and reliability of examination, and is expected to be used especially for continuous follow-up examination. 相似文献
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提出了三面顶点“流形”曲面立体完整画隐线图的标记理论和方法。在三面顶点曲面立体完整画隐线图中合法的节点型式共有69种,其中Y型节点有8种,W型节点有16种,S型节点有11种,V型节点有34种。对曲面立体完整画隐线图进行标记,能够判断其是否可能为“流形”曲面立体的投影,区分正确与不正确画隐线图。提出的完整画隐线图标记方法也适用于平面立体画隐线图。算例证明曲面立体完整画隐线图标记方法是正确、可行和有效的。 相似文献
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As preprocessing for the two-dimensional cutting stock problem or pallet loading problem, we compute the minimum area convex hull. Given two polygons P and Q, we find their relative positions such that the convex hull encasing them is minimum in area. Let N be the total number of vertices in P and Q. We determine the minimum area convex hull in O(N) time. Q is allowed to translate by any amount relative to P, while assuming a constant number of orientations. Instead of recomputing the convex hull after every translation, we update the computed area at certain critical points. Linearity follows by showing that there are O(N) such critical points. 相似文献