基于视场拼接的全视差三维显示系统

提出了一种新的基于视场拼接的全视差三维显示方法及图像生成方案.系统核心部分由一个微投影机阵列、一个反射光路和一个散射屏组构成,图像生成方案采用基于OpenGL的算法实现.为了验证所提出的基于视场拼接理论的正确性,利用液晶显示器、菲涅耳镜组、定向散射屏和背投式反射光路搭建了实验样机.该装置可以在更紧凑的系统结构下显示包括横向视差和纵向视差在内的三维图像,并且通过图像生成算法的配合实现了动态三维显示效果.     

基于双层微透镜阵列的移动视差式立体显示屏

受限于微透镜的数值孔径和像差问题,目前移动视差式立体显示屏存在多视场空间、视场区之间存在视场跳变、主视场空间角度小、显示效果模糊等问题.本文基于离散采样思想,分析了移动视差型三维显示系统的工作机理,结合加工工艺,设计了复合曲面反射层的双层微透镜阵列屏.仿真结果表明:所设计显示屏的视场观看空间角可提升到60°,相对于传统的三维显示屏,双层微结构显示屏可有效提高视场角和显示性能.     

周视悬浮立体显示系统的光学系统设计

基于双目视差原理,提出了一种新型的周视悬浮裸眼立体显示系统。采用菲涅尔透镜和单向散射屏实现了观察范围的纵向拓展,形成的三维图像可周视观看,有悬浮感且可触摸。对系统中采用的定向屏、旋转光阑、条状出瞳,以及投影机的投影距离进行了分析和设计。经过实验验证,立体图像合像舒适,显示效果明显。     

基于变形目镜和OLED的全景周视成像与显示技术

在车载、舰载等运动载体或单兵警戒值守等狭窄空间,传统显示方法难以兼顾显示视场与显示分辨率。针对该问题,本文研究了一种基于变形目镜的全景/周视成像技术与系统。系统采用3路低照度摄像机+4 mm焦距镜头,构成150°左右的全景成像视场,基于FPGA处理平台完成全景图像解析、拼接、校正和显示等算法,实现视频图像大视场拼接与1/3缩放实时显示;由OLED微显示器、变形目镜组和大目镜组成的显示系统使视频图像横向扩大3倍,实时显示全景高分辨动态场景图像。实验系统对全景成像显示技术进行了验证,在军用和民用领域具有广泛的应用前景。     

大视场复眼结构图像处理算法研究

针对多维子眼成像通道曲面排布组成的大视场复眼结构,提出了一种切割-旋转-映射的图像处理算法来实现多通道图像的大视场拼接.通过确定复眼结构的排布特征,分析了各成像通道捕获的子眼图像之间的相互关系,去除相邻子眼图像之间的冗余部分,并运用几何光学及成像光学原理,研究了子眼图像与三维映射空间之间的关系,从而实现了二维子眼图像在三维空间的大视场拼接.实验制备了包含37个镜头且视场角可达118°的人工复眼结构,并运用提出的图像处理算法处理制备的复眼结构捕获的子眼图像.结果表明:算法处理图像过程中不损失图像的分辨率,可以有效地实现多通道图像的大视场拼接,且获得的图像可视性强,满足实用化要求,可进一步推进曲面复眼成像系统的应用.     

基于SIFT匹配算法的多视点自由立体显示视差图像的生成

提出了一种利用同一场景的两幅视差图像生成用于多视点自由立体显示的多幅视差图像的方法。首先运用SIFT匹配算法从两幅视差图像中寻找匹配点,并运用生长运算得到图像的稠密匹配;然后根据匹配点坐标对视差进行了近似计算并得到左视差图像的深度图像;最后提出一种基于投影原理的多幅视差图像生成方法,由左视差图像和其深度图像生成了应用于多视点自由立体显示的多幅视差图像,其立体显示效果良好。     

基于片间相关性的光线空间插值与视点绘制研究

提出了基于片间相关性的光线空间插值算法,利用邻近参考片已知视差,快速预测当前片视差,使得当前片视差估计的搜索限制在预测视差附近的小范围内进行,从而大大降低了计算复杂度.根据视差参考方式的不同,设计了三种实现方案.实验结果表明,采用双向视差参考方案插值生成的光线空间片不但信噪比高、绘制视点图像主客观质量较高,而且插值与绘制速度也有了明显提高.     

基于大视场人工复眼定位技术

针对大视场目标探测提出了一种基于人工复眼大视场定位方法.通过分析子眼视场角与总视场角之间的关系,并结合多目视觉定位对子眼排布方式的要求,研究了包含多个子眼的人工复眼结构设计方法.通过分析子眼图像与三维空间映射关系,对二维图像进行裁剪并映射于三维立体空间,实现了二维子眼图像在三维空间的大视场拼接.利用子眼图像坐标、空间三维坐标及系统参数间的关系,建立了空间点多目定位数学模型,并编制目标定位算法.制备了包含19个子眼可实现120°大视场角的样机,通过张正友标定法获得系统参数,并进行目标定位实验.实验结果表明,使用设计的人工复眼大视场成像系统对5.35m处目标进行探测,定位误差为0.19%.     

基于柔性靶标定位实现图像拼接的多相机三维测量系统

提出一种基于柔性靶标定位实现图像拼接的多相机三维测量系统,采用一个激光投影仪投影大幅条纹,多相机分布式采集的方法扩展视觉三维测量系统的测量范围。标定过程首先使用小型平面靶标标定基准相机二维图像坐标和相位值到三维世界坐标的映射关系,之后在相邻相机部分视场(FOV)重合的前提下,利用柔性靶标定位标定相邻相机图像坐标的转换关系,最后将各个相机的图像坐标全部转化到基准相机的图像坐标系下完成图像拼接,由基准相机图像坐标到世界坐标的映射完成全局三维测量。实验结果表明,使用图像拼接方法的测量精度略低于相机单视场测量的精度,但精度损失较小,满足工业在线测量的要求。该方法避免使用昂贵的辅助测量仪器和加工高精度大型靶标,为多相机视觉测量提供了成本低、使用方便的解决方案。     

一种基于分割的可变权值和视差估计的立体匹配算法

立体匹配一直是计算机视觉研究领域中的热点和难点.是立体视觉中的关键技术之一.为了消除幕于局部图像的双目立体匹配的歧义性,提出一种基于图像分割及可变权值方窠的初始匹配和贪婪的后处理视差估计策略相结合的市体匹配算法.分割彩色立体图像对,利用分割自适应地分配权值来消除匹配特征相似的歧义性.计算匹配代价得到初始视差.接着,为了更好地消除弱纹理区域、重复纹理区域和宽遮挡区域等复杂歧义性,视差后处理中采用贪婪估计方案,包括基于分割的视差校准、窄遮挡处理及多方向自适应加权最小二乘拟合填充.实验结果表明,基于分割的本算法结构简单,能有效地提高处理局外点的稳健性,并生成高精度的稠密视差.     

Aberration improvement of the floating 3D display system based on Tessar array and directional diffuser screen

The floating 3D display system based on Tessar array and directional diffuser screen is proposed. The directional diffuser screen can smoothen the gap of lens array and make the 3D image’s brightness continuous. The optical structure and aberration characteristics of the floating three-dimensional (3D) display system are analyzed. The simulation and experiment are carried out, which show that the 3D image quality becomes more and more deteriorative with the further distance of the image plane and the increasing viewing angle. To suppress the aberrations, the Tessar array is proposed according to the aberration characteristics of the floating 3D display system. A 3840?×?2160 liquid crystal display panel (LCD) with the size of 23.6 inches, a directional diffuser screen and a Tessar array are used to display the final 3D images. The aberrations are reduced and the definition is improved compared with that of the display with a single-lens array. The display depth of more than 20 cm and the viewing angle of more than 45° can be achieved.     

Full-parallax three-dimensional display using new directional diffuser

A full-parallax three-dimensional(3D) display using a new directional diffuser is demonstrated.The display could present 3D images with 45 views comprising 9 horizontal views by 5 vertical views.The resolution and size of the 3D images displayed are 226×226 pixels and 300×300(mm).The new directional diffuser consisting of two perpendicular lenticular sheets can be widely used in the display domain owing to its low cost and simple process.     

Sinusoidal fringe projection system based on compact and non-mechanical scanning low-coherence Michelson interferometer for three-dimensional shape measurement

We report a sinusoidal fringe projection system based on superluminiscent diode (SLD) as a broad-band light source in conjunction with an acousto-optic tunable filter (AOTF) as frequency tuning device for three-dimensional shape measurement. The present system is based on a compact low-coherence Michelson interferometer system. The conventional interferometric system was modified in which one side of the beam splitter was coated with aluminum oxide which is used as reference mirror. With this modified version, interference fringes can easily be obtained by simply placing the external mirror in contact on the other side of beam splitter. Sinusoidal fringes with multiple spatial-carrier frequency can be generated in real-time using the present system by means of changing the radio-frequency signal to AOTF electronically without mechanically moving any component in the system. The present system was tested by projecting the sinusoidal fringes on a step-like object and 3D shape of the object was reconstructed using Fourier transform fringe analysis technique. The main advantages of the proposed system are completely non-mechanical scanning, easy to align, high stability because of its nearly common-path geometry and compactness.     

基于人眼视觉的集成成像三维显示分辨率的比较

为了对不同集成成像系统三维显示应用中的视觉分辨效果进行表征, 提出了一种基于人眼视觉的集成成像三维显示分辨率的分析比较方法. 通过分析集成成像三维显示系统的分辨率与人眼在最佳显示观看距离下分辨本领的关系, 定义了相对分辨率参数, 分析了其与集成成像三维显示实际观看时视觉分辨效果的关系. 研究结果表明, 透镜阵列的大小对集成成像三维显示的视觉分辨效果有重要的影响. 针对两个系统实例的理论计算结果表明, 系统间的相对分辨率参数差异是传统分辨率差异的1.75倍, 实验结果与理论分析一致. 该研究方法对三维显示分辨率的评价有一定的指导意义.     

飞行模拟器用投射系统设计

研究了一种瞄准镜用飞行模拟器投射镜头的设计,并给出了模拟器投射镜头的设计实例。模拟器由显示系统、屏幕、投射系统、反射镜组成,模拟图像信号送入模拟器的显示系统,显示系统将视景仿真模拟图像信号投射到屏幕上,屏幕位于投射系统的焦平面上,瞄准镜对由模拟器进入的光线成像实现成像模拟。投射系统由周边系统、中心系统共9路光学镜头组成,投射系统周边系统、中心系统对应于瞄准镜的中心系统与周边系统,中心系统与周边系统的物面位置重合即共物面;中心系统采用摄远物镜镜形式缩短了镜头长度结构更加紧凑。周边系统焦距为f=263．02mm,视场角为2ω=17°,全视场畸边〈0．4％,在屏幕的Nyquist频率处全视场的MTF〉0．9,系统长度330mm;中心系统焦距为f=295．00mm,视场角为2ω=17°,全视场畸变〈0．37％,在屏幕的Nyquist频率处全视场的MTF〉0．9,系统长度283．2mm。投射系统采用全口径出光,同时系统通光口径略大于敏感器的通光口径,降低了系统装配的精度。     

A digital image-based measurement system for a LCD backlight module

A LCD light guide plate is an element of the LCD backlight module that is often used for the display of compact electronic devices. In this study, a vision system is proposed to detect the degree of uniformity of light reflection using a light guide plate before the diffuser has been attached. A new bright spot search and statistical software has been designed and the parameters for the LCD light guide plate can be adjusted before manufacture to provide greater economy and make the device user friendly. Since many different types of backlight modules had to be analyzed in this study, we used different methods to determine the nonuniform factors and the backlight module area for each type. A wrapping algorithm is presented in the searching and statistic process of bright spot. This algorithm can combine the procedures of segmentation process and nonlinear grey scale mapping. After revising carved depth of the poor brightness area, the diffuser was attached and the analysis performed again to verify the design procedure correction. When the source light density is adjusted, the lighting error for the on line inspection is retained to within 3%.     

A ferroelectric liquid crystal spatial light modulator encoded with orthogonal arrays and its optimized design for laser speckle reduction

In laser projectors, speckle reduction can be achieved by projecting a changing binary phase diffuser onto the screen. Here, we sequentially encoded a commercialized ferroelectric liquid crystal spatial light modulator (FLC-SLM) with the rows of a two-level orthogonal array of order sixty-four, thus obtaining a changing binary phase diffuser. With the help of this binary phase diffuser, the subjective speckle contrast ratio on the screen is reduced from C_b=0.71 to C_a=0.1. Based on the experimental results, a simplified transparent FLC-SLM design is first proposed. This newly designed FLC-SLM has two phase modulation depths and can be driven with the passive matrix addressing scheme. Therefore, the control electronics of the proposed FLC-SLM can be significantly simplified compared to the currently used one.     

Shared pixel based parallax barrier 3D display with high brightness

The parallax barrier 3D display is an autostereoscopic display with low cost. However, the conventional parallax barrier 3D display has a disadvantage of low brightness. Therefore, a parallax barrier 3D display based on shared pixels is proposed. The shared pixels have adapted pixel values which limit crosstalk in a low level, so that they can be displayed simultaneously in both two parallax images. These pixels increase aperture ratio of the parallax barrier. Therefore, they can bring high brightness. A prototype of the proposed 3D display is developed and it has higher brightness than those based on the conventional one.     

Orthoscopic integral imaging display by use of the computational method based on lenslet model

In this paper, we propose a computational depth conversion method based on the lenslet model to display the orthoscopic 3D images in 3D integral imaging display. The proposed method permits the synthesis of elemental images for the orthoscopic 3D images at any arbitrary position without any restrictions and requires no additional procedure during the depth conversion process. Due to the lenslet model involved in the depth conversion procedure, the proposed method can broaden the flexibility of 3D image reconstruction in the integral imaging display system. We carry out the preliminary experiments to prove the feasibility of the proposed method. The experimental results reveal that the proposed method is an effective depth conversion method that allows the reconstruction of the orthoscopic 3D images at any arbitrary position.