共查询到17条相似文献,搜索用时 156 毫秒
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结构光测量中快速相位解包裹算法的讨论 总被引:3,自引:1,他引:2
对Schofield等提出的快速傅里叶变换(采用4次傅里叶变换和4次逆傅里叶)解包裹算法和Volkov等提出的相位重建算法(仅采用两次傅里叶变换和一次逆傅里叶变换)进行了讨论,提出基于离散余弦变换的快速相位解包裹算法.指出前两种算法在处理一般带噪音的模拟相位图时具有明显的优势,其处理结果非常接近理想值,而在处理相位变化剧烈或不连续区域的实验相位图(采用四步相移法测量雕刻佛像的三维面形)时出现较大误差,甚至无法处理,而基于离散余弦变换算法能很好的解决这个问题,并且拥有比前两种算法更快的运算速度.在实际应用中,针对不同的相位图把Schofield所提出的算法与基于离散余弦变换的算法结合起来,可以解决大部分相位解包裹问题. 相似文献
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相位恢复法是一种利用多个离焦面光强分布采用基于傅里叶变换的迭代变换恢复瞳面相位分布的波前传感方法。采用改进的傅里叶迭代变换算法,当波前传感范围超过1个波长时,需要在迭代过程中采用相位解包裹算法。针对18块正六边形拼接的复杂光瞳,提出采用路径无关和最小二乘相结合的混合相位解包裹算法,提高了波前传感精度和动态范围。通过仿真比较了所提方法与单独采用一种相位解包裹方法时的波前传感性能,分析了所提方法的动态范围及噪声对算法精度的影响。仿真结果表明,当波前PV值为3.5λ时,算法的精度为λ/43;当噪声RMS值为10(图像为12Bit量化)时,算法的精度优于λ/40。 相似文献
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加权相位解缠算法的解缠精度取决于所提取的质量图的可靠性。目前提取相位质量图的方法大多采用以各个像素为中心的固定窗口法,但当某些像素被噪声严重干扰时,采用固定窗口法提取质量图往往得不到正确的解缠结果。因此,提出了几种自适应加权窗口方法来提取相位质量图,并给出了具体的实现方法和步骤,同时采用加权小波变换相位解缠算法进行相位解缠。实验结果表明,采用自适应加权窗口方法提取相位质量图来确定初始权重系数能获得比较好的解缠效果。 相似文献
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为了快速准确地对含有噪声的包裹相位图进行相位展开,采用理论分析与计算机模拟及实验验证相结合的方法,对基于快速傅里叶变换(FFT)的四种典型算法四次FFT算法(4-FFT)、二次FFT算法(2-FFT)、四次离散余弦变换算法(4-DCT)及横向剪切干涉与FFT相结合的算法(LS-FFT)作了对比研究。结果表明:2-FFT算法运行速度最快,4-FFT算法次之,LS-FFT算法速度最慢;4-FFT算法对含有较强噪声和轻微欠采样的实验数据的处理效果是最好的;LS-FFT算法对强噪声数据的处理效果最差。 相似文献
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Phase unwrapping algorithms, respectively, based on path-following and discrete cosine transform 总被引:1,自引:0,他引:1
This paper describes a path-following phase unwrapping algorithm and a phase unwrapping algorithm based on discrete cosine transform (DCT) which accelerates the computation and suppresses the propagation of noise. Through analysis of fringe pattern with serious noises simulated in mathematic model, we make a contrast between path-following algorithm and DCT algorithm. The advantages and disadvantages of analytical fringe pattern are also given through comparison of two algorithms. Three-dimensional experimental results have been given to prove the validity of these algorithms. Despite DCT phase unwrapping technique robustness and speed in some cases, it cannot be unwrapping inconsistencies phase. The path-following algorithm can be used in automation analysis of fringe patterns with little influence of noise. 相似文献
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基于DCT算法的种子点相位解包算法 总被引:4,自引:1,他引:3
移相干涉术由于其高精度被广泛应用在光学元件的面形测量上,而由移相算法得到的相位数据被包裹在[-π,π]之间。基于区域生长理论的相位解包算法(种子点法)可以高精度地实现连贯区域的相位解包,基于离散余弦变换的最小二乘解包(DCT)算法可以实现矩形区域的相位解包,而实际测量中,经常会碰到被测件的有效区域为非矩形的分离区域。因此,在分析前两种算法优缺点的基础上,提出了基于DCT算法的种子点相位解包算法。首先运用DCT算法对整个包裹相位进行解包,然后运用种子点法分别解包各分离区域,再通过DCT算法求得的种子点干涉级次实现各分离区域解包相位的统一。实验结果表明,该方法克服了种子点法和DCT算法的缺点,可以准确、快速地实现分离区域干涉图包裹相位的解包,且比这两种算法具有更好的稳定性和更高的精度。 相似文献
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A novel phase unwrapping method used in wavelet-transform profilometry is presented to improve the accuracy and speed of the unwrapping process. The wrapped phase of the fringe image is extracted by using wavelet transform. How to establish quality map using scale factor at wavelet ridge is discussed firstly. The proposed method can reflect the reliability of the pixels in fringe image effectively. As the consuming time of traditional flood-fill phase unwrapping algorithm is too long, an improved quality-guided method is used in phase unwrapping process. We divide the wrapped phase map into two levels following the established quality map, and process these two levels using different algorithms. Compared with the traditional flood-fill algorithm, we can get the accurate result while the consuming time of the phase unwrapping process is much less by using the proposed method. Simulation and experiment results verify that the 3D information of the measured object can be obtained rapidly and accurately by using the proposed method. Also the dynamic object can be measured too. 相似文献
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Phase unwrapping is a task common to many applications like interferometry imaging, medical magnetic resonance imaging, solid-state physics, etc. Fourier transform profilometry (FTP) values the height distribution of object, elaborating the interference between a plane reference grating and a deformed object grating. Since the height information is extracted from the phase of a complex function, the phase unwrapping is a critical step of the process. Several unwrapping algorithms are proposed in literature, but applied to measurement technologies different from FTP. The purpose of this paper is to define the performances of eight different unwrapping algorithms applied to FTP optical scan method and to define the best one. The algorithms chosen are: Goldstein's algorithm, quality guided path following method, Mask cut method, Flynn's method, multi-grid method, weighted multi-grid method, preconditioned conjugate gradient method and minimum Lp-norm method. The methods were tested on real images acquired by a FTP scanner developed and calibrated for these experiments. The objects used vary from simple geometries, like planes and cylinders, to complex shapes of common use objects. Algorithms were qualified considering the phase unwrapping errors, execution time and accuracy of the shape of objects obtained from the scan method in comparison with real ones. The results show that quality guided algorithm best fits in FTP application. 相似文献
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This work presents a robust algorithm for phase unwrapping. The proposed algorithm is based on the expansion of the estimated phase through a linear combination of a set of Basis Functions. We present a novel weighted robust functional which is minimised using a two step strategy. This model allows us to reduce the influence of noise and to remove inconsistent pixels in the estimation of the unwrapped phase. The proposed model assumes that the phase is smooth. Under this assumption, experiments demonstrate that if the phase is corrupted by high levels of noise, our model presents a better performance than state of the art algorithms. For low levels of noise, the results are comparable. 相似文献
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基于图切割的相位展开 总被引:1,自引:1,他引:0
剪切散斑干涉术中,普遍采取相移法提取相位,只可得到被包裹的相位信息,进一步量化计算之前,必须展开相位,但是大量的散斑噪音使相位展开变得非常困难.本文提出基于图切割理论的相位展开算法,将相位展开等价于整数的最优估计问题,通过最小化能量函数展开相位,无需对散斑包裹相位图进行滤波,就可以从包含大量散斑噪音的包裹相位图中准确地提取出真实相位,极大程度地保留了相位包裹图中的细节信息.对于同一幅模拟的散斑包裹相位图,传统的质量导向枝切法和最小二乘法的均方根误差分别为11.7076和4.9775,新算法的均方根误差则为0.9459,数值模拟与实验结果均验证了新算法优良的抗噪性能. 相似文献