Linear Phase FIR Filter on Measuring 3-D Surface

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Profilometry with Grating Projection Based on One—step Phase Shift

An optical technique for 3-Dshape measurement is presented.This technique,based on a deformed projected grating pattern which carries 3-D information of the measured object,can automatically and accurately obtain the phase map of a measured object by using one-step phase shift algorithm.In comparison with traditional phase-shift technique,the echnique is much faster,with the equivalent accuracy.Only one frame image is sufficient for measuring.Experimental result of typical object is presented.     

Single Camera 3—D Coordinate Measuring System Based on Optical Probe Imaging

A new vision coordinate measuring system-single camera 3-D coordinate measuring system based on optical probe imaging is presented.A new idea in vision coordinate measurement is proposed.A linear model is deduced which can distinguish six freedom degrees of optical probe to realize coordinate measurement of the object surface.The effects of some factors on the resolution of the system are analyzed.The simulating experiments have shown that the system model is available.     

Subpixel Target Location Techniques for 3—D Coordinate Measuring System

The close photogrammetric 3-D coordinate meaurement is a new measuring technology in the fields of the coordinate measurement machine (CMM) in recent yearsl.In this method,we usually place some targets on the measured object and take image of targets to determine the object coordinate.The subpixel location of target image plays an important role in high accuracy 3-D coordinate measuring procedure,In this paper,some subpixel location methods are reviewed and some factors which affect location precision are analyzed. Then we propose bilinear interpolation centroid algorithm.The experiments have shown this algorithm can improve accuracy of target centroid by increasing available pixels.     

2—D Fourier Transform Method for Optical Measurement of 3—D Surface

A emthod of 2-D Fourier transform used in 3-D surface profilometry is proposed,analyzed and compared with 1-D Fourier transform method in theory and practical measuring result.It was proved that the 2-D Fourier transform method has more advantages over 1-D Fourier transform methodd in biggest crook-rate limits,accuracy and sensitivity of measuring.Styudy on measuring object surface details with large crook-rate changing accurately used new higher-power index low-pass filter of spatial frequency domain.A new method of automatic produced reference grating image and error-correcting is proposed.One undeform row of deform grating image is used to extend a complete reference grating image,and some error-correcting method is used to process the result to get accurate surface shape and the deflection of reference surface normal line deviated from the axle of camera.By this new method,one deform rectangle grating image is only used to get the 3-D shape accurately.     

Spectrum Illumination for 3— Surface Imaging System

A method using spectrum illumination to reconstruct 3-D bject image is a new concept in the field of computer vision.The design of optical illumination system is crucial this method.Several ways to achieve multicolor spectrum illumination are discussed.A prism illumination system is designed by means of aligning symmetrically the prism at the mid-wavelength(nd=1.806 274)of light path and using reflection collimating lens,cylindrical expending lens and two optical shutters.The relations between deviation angles and light wavelengths are given,and some 3-D reconstruction results are presented.     

光栅投影图像的3D表面重建

为了克服全患和双目表面重建的某些弱点，利用光栅投影生成二维图像之几何特性，建立投影二维平面图像和三维空间图像的对应关系，并由此确定三维物体表面点的空间坐标，最后利用计算机图形学和虚拟现实的理论与技术绘制出三维物体表面。     

Automated Phase-measuring Profilometry of 3-D Diffuse Objects Using a Single Phase Step Method

The technique of phase measuring profilometry using a single phase step method is proposed .This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The mehod is able to automatically recognize any position between depression and elevation on an object surface.Theoretical analysis analysis and experimental verification are presented .     

基于线性相位FIR滤波的三维曲面的光学检测

利用一组规则机线投影到物体表面的畸变光珊，采用线性相位ＦＩＲ滤波技术解调出含有物体表面高度信息的相位。建立了一种较二维ＦＦＴ法更快，精度较高的光不检测技术。该技术只需采集一幅图象，不需要确定条纹级次，不存在“凹凸模糊”的问题。本文给出了一个典型试件的实验结果及分析。     

基于雷米兹交换算法设计线性相位对数FIR滤波器

根据线性相位对数FIR滤波器幅度响应与线性相位FIR滤波器幅度响应的关系 ,将线性相位对数滤波器设计转换为线性相位FIR滤波器设计。该方法直接采用雷米兹交换算法即可获得线性相位对数滤波器通带和阻带的等纹波特性。另外 ,该方法既可基于频域均匀采样也可基于频域非均匀采样 ,具有一定的通用性和灵活性     

基于Matlab加噪语音的FIR滤波器设计

传统的FIR滤波器设计是根据给定的频率指标,设计出满足指标的系统函数.本文提出一种基于Matl8b加噪语音的FIR滤波器设计方法.该方法首先通过Matlab产生单频噪声,加入到语音信号中,并改变单频噪声的频率来调整FIR滤波器设计的难度;然后,根据混入噪声信号的频谱,设计出所需要的滤波频率指标;选择合适的窗函数,设计满...     

Multidimensional Two-channel Linear Phase FIR Filter Banks and Wavelet Bases with Vanishing Moments

In the paper new design methods for multidimensional two-channel perfect reconstruction (PR) FIR filter banks are described. The filters have linear phase, achieve an arbitrarily high number of vanishing moments and can be used to obtain biorthogonal wavelet bases. Two-dimensional wavelet bases with square, rectangular, and hexagonal support are constructed. A design method that trades off vanishing moments and frequency selectivity is described. These two properties are both important in subband coding, but they each require a share of the degrees of freedom available from the total number of filter coefficients. Novel analytic formulae are derived and are applied to provide illustrative examples.     

线性相位FIR滤波器频域特性的教学探索

线性相位FIR滤波器的频域特性分析是"数字信号处理"课程中的一个重要内容。本文给出了一种与传统教材不同的线性相位FIR滤波器频率响应的分析方法。笔者以Ⅰ型线性相位系统的频率响应为基础,证明了Ⅱ型、Ⅲ型和Ⅳ型线性相位FIR滤波器的频率响应可表示为Ⅰ型线性相位系统的频率响应与简单函数的乘积。该方法特点是分析过程简捷,突出了不同类型线性相位FIR滤波器频域特性,便于学生掌握线性相位FIR滤波器频域特性。     

Optimal McClellan transformation and its application to 2-D FIR digial filter design

A new method to choose the coefficients of the McClellan transformation is developed. The coefficients are obtained by using both analytic and nonlinear optimization approaches. The transformation using the proposed method has much better approximation performance for circular symmetry than the existing methods, especially when the cutoff frequency of the 2-D filter is very large. The proposed method also applies to choose the transformation coefficients to approximate elliptic contours. Two design examples of 2-D FIR digital filters demonstrate the good performance of the proposed method.     

高采样率FIR数字滤波器的设计与实现

介绍了在数字算法设计和实现中基于ＦＰＧＡ四输入查找表结构的ＦＩＲ滤波器流水线设计技术,和结合先进的ＥＤＡ软件进行高效设计的方法和途径,给出了设计的仿真结果。该设计能满足高采样率的要求,设计效率高,对ＦＰＧＡ硬件资源的利用高效合理,而且文中提到的基于流水线技术的算法分解方法可推广应用到其它需要高速数字算法实现的领域中,从而充分挖掘和利用ＦＰＧＡ的高速特性。