基于SFS方法的快速人脸三维重构系统

为了实现快速重构人脸三维形状的需求,设计了一种基于SFS方法的人脸重构系统。首先由摄像机获取点光源作用下的人脸表面图像,其次假定人脸表面的反射特性遵循Lambert定律,建立透视投影下的人脸图像辐照度方程,然后将该方程转化为包含人脸表面深度信息的静态Hamilton-Jacobi偏微分方程,最后由系统软件求得该方程的解,进而重构出人脸表面的三维形状。实验结果表明,该系统可以快速获得较高的重构精度,在1.5 s内可以达到0.17%的高度平均相对误差。     

Fast 3D Face Reconstruction System Based on SFS Method

为了实现快速重构人脸三维形状的需求,设计了一种基于SFS方法的人脸重构系统.首先由摄像机获取点光源作用下的人脸表面图像,其次假定人脸表面的反射特性遵循Lambert定律,建立透视投影下的人脸图像辐照度方程,然后将该方程转化为包含人脸表面深度信息的静态Hamilton - Jacobi偏微分方程,最后由系统软件求得该方程的解,进而重构出入脸表面的三维形状.实验结果表明,该系统可以快速获得较高的重构精度,在1.5s内可以达到0.17％的高度平均相对误差.     

基于结构光的高反物体三维形貌测量方法

提出了一种用于大面积高反物体的三维形貌测量方法。基于双色反射模型理论,提取了相机采集的条纹图像的漫反射分量,通过改进的反射分量分离算法对图像进行反射分量分离;对反射分量分离产生的图像空洞采用改进的种子填充算法进行修补;用三步相移结合质量引导算法得到连续相位,由系统标定的相位高度映射关系得到物体的高度信息。实验结果表明:所提方法实测误差约为0.23 mm,消除了93%～97%的高光像素,有效克服了反射光的干扰,对大面积反射光具有较好的稳健性。     

基于神经网络的红外焦平面光学非均匀性校正改进算法

基于场景的非均匀校正依然是红外领域的一个研究热门。神经网络算法是一种较为典型的场景校正算法。本文主要针对神经网络算法本身不能校正光学引入的非均匀性问题,提出了新的改进算法,通过对神经网络输入层的预处理,消除图像的低频噪声,此外,为了消除预处理对图像对比度的影响,本文增加了神经网络的层数,使用双层神经网络对算法进行更新,从而消除了图像对比度下降的现象。实验结果表明,改进的神经网络算法能够有效的改善图像质量,消除图像中光学引入的非均匀性。     

一种适于镜面反射表面的从明暗恢复形状算法

为了实现镜面反射表面快速重构的需求,提出了一种基于高阶Fast Marching方法的从明暗恢复形状算法。首先假定光源为点光源,且位于无穷远处,其次认为摄像机遵循正交投影,其方向与光源方向保持一致,接着使用Blinn-Phong模型来描述镜面反射表面的反射特性,建立基于Blinn-Phong反射模型的镜面表面图像辐照度方程,然后将该辐照度方程转化为含有高度信息的Eikonal偏微分方程,利用高阶Fast Marching方法计算上述Eikonal方程的解,从而获得镜面反射表面的三维形状。实验结果表明:提出的方法可以快速精确地实现镜面反射表面的三维重构。     

基于SFS方法的超空泡三维重构研究

有关超空泡的三维重构研究对于超空泡的水下试验测试和相关研究工作有着深远的意义。通过采用阴影恢复图像的方法（即SFS方法）对超空泡的实验图像进行三维重构,并与理想光照条件下的半球重构图像进行对比分析,为以后有关超空泡的三维重构研究提出了改进的方法。     

基于虚拟现实技术的三维图像重构研究

针对传统基于主动偏振成像的三维图像重构方法重构过程中图像统计信息表达能力较差,导致重构后三维图像精度低,研究一种基于虚拟现实技术的三维图像重构方法。选取Visual C++可视化软件开发平台和VTK三维图像处理软件作为三维图像重构实现平台,将原始图像通过数据输入以及文件解析等步骤导入计算机后,对原始图像进行图像滤波、图像分割以及图像插值等预处理,处理后的图像在VTK软件中利用包围盒法先构建图像重构的三维数据场,依据图像重构三维数据场绘制图像三维直接体,通过图像三维直接体获取三维图像重构输出公式,实现基于虚拟现实技术的三维图像重构。仿真结果表明,采用该方法对10幅图像进行三维图像重构,重构图像平均遍历覆盖度高达97.99%,重构精度均高于97%。     

基于参数域映射及B样条插值的三维重构方法

利用单目CCD图像进行物体表面非接触测量的核心是基于单幅图像的三维重构技术,常采用由阴影恢复形状(SFS)的方法实现三维重构。当图像分辨率较低时,通过由阴影恢复形状的方法重构的三维表面模型其分辨力较差,无法满足实际要求。为此提出了一种基于参数域映射及B样条插值的三维重构方法。采用B样条插值技术对图像进行放大处理,通过像素的参数域映射减小图像的失真及高频信息的丢失,根据放大后图像的灰度信息重构物体的三维表面模型。实验表明,基于参数域映射及B样条技术的图像插值方法很好地保护了图像的细节,利用该方法进行三维重构能够有效改善重构模型的分辨力和光顺性,为提高三维表面非接触测量精度创造了条件。     

基于局部Lax-Friedrichs通量分裂格式的透视SFS

提出了一种基于局部Lax-Friedrichs通量分裂格式的快速扫描算法,用以解决透视投影下的SFS问题。先对透视投影SFS进行建模,将其转换为静态Hamilton-Jacobi方程,再结合局部Lax-Friedrichs通量分裂格式和快速扫描算法对静态Hamilton-Jacobi方程进行求解,从而得到物体表面。本文算法可以用于非凸Hamiltonian函数的情况,提高了局部分析能力,不需要对初始高度进行估计,且算法简单,易于实现。对合成图像和实际图像的实验表明本文算法可以得到较好的透视投影SFS的恢复结果。      

彩色和等色图像的非监督反射分量分离

反射分量分离是计算机视觉和数字图像处理中的一个重要问题。尽管已有很多基于单张图像的反射分量分离方法,但这些方法只能分离图像中彩色区域的反射分量并会在等色区域产生严重的噪声。本文提出一种能够分离图像彩色和等色区域反射分量的方法。彩色和等色区域高光的共同特征是亮度在局部区域中逐渐变化,因此本文算法首先将亮度信息融入传统的无高光图像,提出能够区分不同亮度等色区域的改进的无高光图像;然后提取局部位置空间亮度差异特征和局部颜色空间亮度差异特征,并用K-Means方法检测图像中的镜面反射像素;最后用颜色传递方法估计出漫反射分量,实现漫反射和镜面反射分量的分离。实验结果表明本文算法能够同时有效地分离彩色和等色区域的反射分量。本文算法扩展了反射分量分离方法的应用范围。      

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.