共查询到20条相似文献，搜索用时 62 毫秒
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在用机器视觉在线自动测量大尺寸零件的直线轮廓尺寸时,为了消除序列图像拼接中的旋转偏差,提出了一种基于链码搜索的新算法.将序列图进行滤波、分割、边缘提取预处理后,搜索边缘轮廓线的链码长度,根据链码长度求出轮廓线与坐标轴间的夹角,将序列图反向旋转这一角度,使序列图中直线轮廓方向与坐标方向一致,从而消除了序列图的旋转偏差,为后续拼接中消除平移偏差做好准备.对旋转偏差为0°～9°的线性轮廓零件进行了实验,结果表明:与经典的Hough变换相比,新方法精度更高,速度更快,这对实现大尺寸直线轮廓零件在线高精度测量具有重要实用价值. 相似文献
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曲线和方程、曲面和方程是研究空间坐标系中的某些曲线、曲面与某些方程间的一一对应关系。研究空间曲线、曲面的两个基本问题是:已知空间曲线、曲面作为点的轨迹求其方程;已知空间曲线、曲面上点的坐标间的关系式研究其形状。 相似文献
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利用奇异混合函数将双三次B样条曲面与虚拟曲面片作混合,构造一类可插值给定数据点的插值曲面,该类曲面在边界处可达到C~2连续,参数α可对曲面片整体形状进行调控。进一步,构造了可局部调控形状的带形状参数的插值曲面。 相似文献
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为了解决低对比度成像条件下传统三维轮廓重建算法精度偏低的问题,提出一种基于邻域距离最小化准则、由粗到细的高精度轮廓三维重建算法。首先使用 Canny 算子对目标图像进行边缘检测,再利用目标形状、尺寸等先验信息剔除分割出的虚假目标边缘。随后,计算边缘点法线方向上的梯度加权值作为工件初始化轮廓,根据左右一致性原则筛选出粗匹配点对,在匹配点对邻域附近使用亚像素进行精细搜索,利用邻域距离最小化准则估算出当前最佳亚像素匹配点对,并将其用于激光刻形工件的尺寸测量,总体精度可达 0.1mm。该方法有效降低了轮廓重建算法对边缘定位精度的依赖,同时提高了轮廓重建精度。 相似文献
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有理Bézier曲线具有很多良好的性质,是曲线曲面设计的重要方法.根据给定的型值点,通过构造有理Bézier样条插值曲线的公式,给出了计算方法,并且分析了重节点情形曲线的形状和特点,最后通过数值实例验证了方法的有效性. 相似文献
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有理Bézier曲线具有很多良好的性质,是曲线曲面设计的重要方法.根据给定的型值点,通过构造有理Bézier样条插值曲线的公式,给出了计算方法,并且分析了重节点情形曲线的形状和特点,最后通过数值实例验证了方法的有效性. 相似文献
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《兰州石化职业技术学院学报》2021,21(2)
接触式轮廓仪在测量工件或产品的轮廓时,由于探针有磨损、探针上有玷污等问题会导致检测到的轮廓曲线呈现出凹凸不平的情况,此外由于工件放置的位置或测量角度的不同,也会导致检测到的轮廓线产生形变,这给工件形状的准确标注带来影响。利用图像几何校正算法将其图像进行水平校正,在其校正后,利用数据分段拟合出工件的轮廓曲线模型,再利用数学方法求得轮廓曲线的各项参数值。通过以上工件自动标注方法,可以较好的替代人工计算,很大程度的解决了接触式轮廓仪工作中存在的问题。 相似文献
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着重讨论帧间预测码运动补偿算法，该算法可获得比一般的运动块匹配方法更大的峰值信噪比。该基于小波变换域的块搜索匹配算法，在运动比较平缓时能以很少的运算次数马上找到块匹配点；在运动非常激烈时，则首先采用小波变换，然后再用本方法进行块匹配搜索，可减少大量复杂的运算量。 相似文献
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为简化伸缩变形计算过程,针对代数曲线和参数曲线,提出一种具有区域峰值的伸缩因子曲线变形方法。首先基于 Hermite 插值基函数构造一种多项式伸缩函数,然后建立带有伸缩参数的伸缩因子,最后将伸缩因子作用于曲线,促使曲线沿指定方向产生变形。在变形过程中,通过改变伸缩因子中的形状控制参数,实现曲线整体、局部以及周期变形效果。大量数值实例证明,该方法计算量小,便于理解和操作,可获得适用于不同设计要求的旋转曲面和外形轮廓线。与其它方法相比,该方法不仅可用于参数型曲线,还可用于隐式表示的代数曲线,丰富了隐式曲线的变形效果。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献