共查询到19条相似文献,搜索用时 140 毫秒
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基于局部分形维数的遥感图像分割 总被引:1,自引:0,他引:1
本文针对遥感图像的分形特点,采用局部分形维数进行图像分割.利用金字塔模型替代了局部分形计算中的窗口模板,从而对局部三角棱柱面法进行了改进,减少了图像局部分形维数的运算量.并设计了一种新的递归计算流程,有效地降低了内存存储量.利用此法对遥感图像进行分割,结果表明:改进后的三角棱柱面法提高了基于遥感图像纹理特征的图像分割方法的计算速度,同时保留了三角棱柱面法对于分形维数计算的准确性. 相似文献
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基于分形维数的柑橘形状与光滑度的机器视觉分级 总被引:4,自引:0,他引:4
为了实现柑橘形状与果皮光滑度的自动分级,研究了柑橘分形维数与柑橘形状和果皮光滑度间的对应关系.对机器视觉系统采集的柑橘花萼面和侧面的图像设置蓝色分量阈值去除背景后,经图像二值化、四连通化边界跟踪和边界细化操作,提取柑橘边界周长和柑橘区域面积,利用周长一面积方法计算柑橘分形维数,以此度量柑橘形状和果皮光滑度.3组仿形样本的分析表明,分形维数随形状和表面光滑度的变化而变化,说明分形维数既概括了柑橘外部形状特征,同时又包含了果皮光滑度信息.用10个柑橘检验样本的分形维数评定柑橘等级,其结果与人工感官判断结果完全吻合,这表明:分形维数能对柑橘形状和果皮光滑度进行分级. 相似文献
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分形插值是拟合数据的一种新方法,它可以反映出曲线和曲面上的粗糙性质.本文介绍了基于仿射分形插值函数的分形插值曲面的构造方法,给出了连续函数中心变差的概念,讨论了中心变差与变差、中心变差与计盒维数之间的关系.研究了这类分形插值曲面所对应的二元连续函数中心变差的性质,并根据二元连续函数中心变差与函数图像计盒维数之间的关系,得到了这类分形插值曲面的计盒维数. 相似文献
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将分形理论引入到介孔碳孔结构表征,基于SEM图像计算二维分形维数(D2)及三维分形维数(D3),并分析了分形维数与孔结构参数之间的规律.结果表明,D2及D3能有效地量化介孔碳形貌的差异,两者随形貌的变化一致,即D2越大D3也越大.当介孔碳的显气孔率相近时,平均孔径越小D2和D3越大,反映出介孔碳具有越多的细部特征和越粗糙的表面. 相似文献
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利用分形理论盒维数法对复合材料第二相颗粒分布均匀性进行定量评价,通过MATLAB建模实现图像的数字化处理,对盒维数MATLAB模型的准确性进行实验验证,并分析视场边界颗粒对盒维数的影响;对3个不同颗粒分布的图像进行颗粒分布均匀性的评价,并将实验结果与锐角比率法的评价结果进行比较。结果表明:除去与不除边界颗粒二次分形计算的盒维数呈线性关系;对颗粒均匀分布图像进行分形计算得盒维数为1.998,与理论值为2的误差为0.077%;盒维数评价法有效可行,且区分度明显。 相似文献
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从损伤力学的基本理论出发,推导了应力波在节理岩石中传播波速的解析解,建立了节理面图像分形维数与波速间的关系。为了从数值角度探讨节理面图像维数对波速的影响规律,基于图像每一像素颜色可表示为一个三维空间矢量的基本假定,构建了节理面图像的粗糙“颜色表面”模型,计算了该“颜色表面”的分形维数,此维数即为节理面图像维数,并通过实例验证了该法的可行性。在此基础上,通过数值方法探讨了波速随图像维数的变化规律,研究显示:随着节理面图像维数增大,节理面粗糙程度的增加,应力波波速相应减小,且在不同的图像维数区间里,波速减小的速率也有所不同 相似文献
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Piotr Kotowski 《International Journal of Fracture》2006,141(1-2):269-286
In this study, a complete method of determination of the fractal dimension for fracture surfaces of ferrous alloys has been
proposed. This dimension is determined for the vertical profile obtained by the profile technique cross-section. The image
of the profile, seen through the microscope coupled with a camera, is recorded in a computer, where numerical processing is
performed. For calculation of the same fractal dimension, the fd3 program has been used, which is available through the Internet.
The essential element of the method is optimisation concerning microscopic magnification (scale of a length), resolution of
the recorded image and selection of the grey level threshold at binarization. The tests for the stability of discretization,
which enable minimization of the error of the measurement, have also been carried out. These tests consist in checking the
difference in fractal dimensions for the same profile obtained in two different methods of contouring as well as the difference
between capacitive, informative and correlative dimensions. In both cases, too big difference suggests that the determined
dimension is not reliable. This method allows determination of the fractal dimension with an absolute accuracy of 0.05 in
non-dimensional units. The method has been employed in many studies. In this paper the following tests have been presented:
a “fractal map” of the fracture surface was made, an influence of the mechanical notch radius in a compact specimen on the
fractal dimension of the fracture surface, an influence of the distortion rate on the fractal dimension, an effect of fatigue
crack propagation rate on the fractal dimension and influence of the stress-intensity factor on the fractal dimension of the
fracture surface. The following materials were examined: Armco iron, P355N steel and 41Cr4 steel in different states after
the heat treatment. The measurements have been made for the specimens of the compact type. There was considered an influence
of location of the place of measurement on the fractal dimension being determined. The dimension was determined on the profiles
lying longwise and crosswise the crack propagation direction. It has been found that the fractal dimension of the fracture
surface does not depend on a place of measurement. This suggests, among other things, that a distinction between the places,
which were created under conditions of the plane stress, and the places, which were created under conditions of the plane
strain state, cannot be made with the help of the fractal dimension. When testing an influence of the radius of the mechanical
tip notch on the fractal dimension of a fracture surface, this dimension was determined in the places located at different
distances from the tip of the mechanical notch. With respect to the radii up to 1.0 mm, no significant differences in fractal
dimensions have been found. The fractal dimensions of the fracture surface for all examined materials were practically the
same and they ranged from 2.02 to 2.10. However in some ranges of da/dN rate the dimension was changing inversely proportional to da/dN. Obtained results confirm that fractal dimension do not depend on the investigated material. 相似文献
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本文研究了超高强度钢D6Ac的断裂韧性、冲击韧性和拉伸面缩率与断口分形维数的关系。分别用二次电子线扫描和数字图象法测定断裂韧性试样的断口分形维数,得出试样的韧性与分形维数Dse、D_H和D_L成正比关系,即韧性随分形维数增大而增加。试样断口的粗糙度由夹杂物引起的差异小于金相组织不同引起的差异时,使用数字图象法测得的分形维数与韧性的线性关系优于二次电子线扫描的结果。 相似文献
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粉体颗粒群粒度分布分形维与流动性及流动助剂影响关系研究 总被引:2,自引:0,他引:2
粉体颗粒粒度分布分形维能很好地表征颗粒群粒度分布情况,对表征颗粒流动性具有重要意义.通过建立便于用数字显微和图像处理计算颗粒粒度分布分形维数值的数学模型,采用图像处理技术得到粉体颗粒粒度分布分形维数值,探讨流动性表征参数休止角、崩溃角和差角与粒度分布分形维数值间的关系,确认颗粒粒度分布分形维数值可用于表征粉体流动性,形成了可靠和简洁的粉体流动性能测定新方法.并就流动助剂对粉体流动性能的改进与分形维数值关系做了初步探讨,得出了分形维数值可作为掺杂流动助剂量的指导参数的结论. 相似文献
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为监测大气颗粒物的来源,根据静电吸附原理设计大气颗粒收集装置采集大气颗粒物,通过光学显微放大技术和图像分析方法,得到源颗粒的轮廓分形维数值,结合采样点周边的实际情况,分析和对比各源颗粒的轮廓分形维数值,确定颗粒部分来源;并采用偏光显微镜观察各源颗粒的偏光特征,协同确定大气颗粒的具体来源。结果表明,大气颗粒具有分形特征,其很多特性均与其分形特征有关;采用大气颗粒的轮廓曲线分形维数值作为降尘颗粒来源的辨析参数是可行的,轮廓曲线的分形维数值能很好地表达颗粒的结构形态,特定颗粒源的分形维数值具有一定的范围;将轮廓曲线的分形维数值与各源颗粒的偏光特征相结合,对颗粒来源的辨识准确率在90%以上。 相似文献
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An analytical model is presented for the determination of the fractal dimensions of particles which are widely used as reinforcement
in nanocomposites. The model is used to characterize the surface irregularity or roughness. It was found that fractal dimensions
of both the contour and surface of particles depend only on the relative particles size ratio between secondary particles
and subunits. It is proposed that, in practical applications, the fractal dimension of a certain reinforcement particle can
be obtained by a combination of this model and a state-of-the-art instrument that can determine the sizes of primary and secondary
particles by image analysis. It is possible to relate the fractal dimension with the adhesion and other physical and chemical
properties at the interface between particles and matrix. 相似文献
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选取燃煤锅炉、道路扬尘、汽车燃油不完全燃烧产生的颗粒、土壤颗粒等4种颗粒,利用数字显微和图像处理技术,求取降尘颗粒轮廓投影曲线的分形维数,并根据实际采样情况,求取降尘部分源颗粒的轮廓投影曲线分形维数,根据分形维数间的关系对比分析后判断降尘颗粒的来源。结果表明:将大气降尘轮廓投影曲线分形维数值作为降尘颗粒来源的辨析参数是可行的,将轮廓投影曲线的分形维数值和投影轮廓的其他几何特征参数相互结合可以得到很好的判断结果。 相似文献
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提出一种将双树复小波与分形理论相结合的复合评定方法。即利用双树复小波近似的平移不变性和方 向性好等优点,将信号分解成更为细腻的低频和高频信号,同时根据多尺度下信号分形维数的不变性,利用图像灰 度值自相关求得高低频信号的分形维数,通过计算高低频信号分形维数之间的差值(即分形维数距)来确定双树复 小波的分解尺度。仿真结果表明复合评定法可以较好地提取基准面,且分形维数距确定分解层数的准确性通过均 方根*Sq值得到了验证;两个实例均说明,复合评定法可以很好地提取具有分形特征的纳米级三维粗糙表面基准或 波纹度,为实际工程表面评定提供了可靠的理论基础。 相似文献