Projection‐based head‐tracking 3‐D displays

Abstract— This paper describes the construction and operation of four 3‐D displays in which each display produces two images for each eye and thus fits into the category of projection‐based binocular stereoscopic displays. The four 3‐D displays described are pico‐projector‐based, liquid‐ crystal—on—silicon (LCOS) conventional projector‐based, 120‐Hz digital‐light‐processor (DLP) projector‐ based, and the HELIUM3D system. In the first three displays, images are produced on a direct‐view LCD whose conventional backlight is replaced with a projection illumination source that is controlled by a multi‐user head tracker; novel steering optics direct the projector output to regions referred to as exit pupils located at the viewers' eyes. In the HELIUM3D display, the image information is supplied by a horizontally scanned, fast, light valve whose output is controlled by a spatial light modulator (SLM) to direct images to the appropriate viewers' eyes. The current statu s and the multimodal potential of the HELIUM3D display are described.     

Optical simulation for cross‐talk evaluation and improvement of autostereoscopic 3‐D displays with a projector array

Abstract— Multi‐view spatial‐multiplexed autostereoscopic 3‐D displays normally use a 2‐D image source and divide the pixels to generate perspective images. Due to the reduction in the resolution of each perspective image for a large view number, a super‐high‐resolution 2‐D image source is required to achieve 3‐D image quality close to the standard of natural vision. This paper proposes an approach by tiling multiple projection images with a low magnification ratio from a microdisplay to resolve the resolution issue. Placing a lenticular array in front of the tiled projection image can lead to an autostereoscopic display. Image distortion and cross‐talk issues resulting from the projection lens and pixel structure of the microdisplay have been addressed with proper selection of the active pixel and adequate pixel grouping and masking. Optical simulation has shown that a 37‐in. 12‐view autostereoscopic display with a full‐HD (1920 × 1080) resolution can be achieved with the proposed 3‐D architecture.     

3D interactive system based on vision computing of direct‐flective cameras

A bare‐finger 3D interactive technology for portable devices was developed. Using directive‐flective cameras to reform the field of viewing, a blind working range close to the camera is eliminated. Moreover, the algorithm of vision computing, different from skin color detection, is presented to determine the positions of fingertips. The interactive range is workable from 1.5 to 50 cm above the entire surface of the display. The mean position error of less than 1 cm is achieved. This accuracy realizes a camera‐based 3D interactive system allowing for near‐distance functionality. Therefore, floating 3D images can be touched and interacted with, potentially creating more application and intuitive user‐machine interface.     

Bare finger 3D air‐touch system with embedded multiwavelength optical sensor arrays for mobile 3D displays

A camera‐free 3D air‐touch system was proposed. Hovering, air swiping, and 3D gestures for further interaction with the floated 3D images on the mobile display were demonstrated. By embedding multiwavelength optical sensors into the display pixels and adding angular‐scanning illuminators with multiwavelength on the edge of the display, the flat panel can sense images reflected by a bare finger from different heights. In addition, three axis (x, y, z) information of the reflected image of the fingertip can be calculated. Finally, the proposed 3D air‐touch system was successfully demonstrated on a 4‐inch mobile 3D display.     

How color break‐up occurs in the human‐visual system: The mechanism of the color break‐up phenomenon

Abstract— In the present set of experiments, we examined the mechanisms underlying color break‐up (CBU), a phenomenon observed when images produced with a color‐sequential projector are viewed. The perceived position of CBU was measured during fast eye movement, saccade with static and briefly flashed stimuli. Results showed that CBU did not simply correspond to the locus of the stimulus on the retina during saccades, because the width of the CBU perception was narrower than the distance of the eye movements. This effect was thought to be related to visual stability, which allows objects to be perceived as stationary even when the eyes move and the retinal image changes position. Visual stability is assumed to operate by compensating for the change in retinal image position using eye‐position signals; however, this compensation is imperfect during saccades. Thus, incomplete compensation results in a CBU perception that is of a narrower width than the amplitude of the saccade. In conclusion, CBU cannot be simulated with moving video cameras because it results largely from the mechanisms of visual perception. Large inter‐individual differences in perception of CBU were also found. This observation also supports the idea that CBU depends on the mechanism of perception.     

High‐visibility 2‐D/3‐D LCD with HDDP arrangement and its optical characterization methods

Abstract— A 3.1‐in.‐diagonal 2‐D/3‐D LCD with a novel pixel arrangement, called horizontally double‐density pixels (HDDP), for high‐quality 3‐D images has been developed. 3‐D visibility has been improved by broadening the qualified stereoscopic viewing space (QSVS) where high‐quality 3‐D images can be seen. In order to evaluate the QSVS, optical characterization methods, based on the ergonomics for stereoscopy, such as 3‐D crosstalk, interocular luminance difference and 3‐D moiré have been proposed. The implementation results show that these methods can correctly evaluate high‐visibility autostereoscopic displays.     

Design conditions for attractive reality in mobile‐type 3‐D display

Abstract— An autostereoscopic 3‐D display suitable for the mobile environment is prototyped and evaluated. First, the required conditions for a 3‐D display in a mobile environment are considered, and the three major requirements are clarified: small size, viewing‐position flexibility, and application support. An application of a mobile‐type 3‐D display should be different from that of a large‐sized 3‐D display because a mobile‐type 3‐D display cannot realize the feeling of immersion while large‐sized 3‐D displays can realize it easily. From this assumption, it is considered that it is important to realize the feeling to handle a 3‐D image. Three types of 3‐D displays are developed to satisfy these requirements. They are subjectively evaluated to confirm their attractiveness. Results of the tests show that intuitive interaction can increase the reality of the 3‐D image in the sense of unity and also can improve the solidity and depth impression of the 3‐D image.     

2‐D/3‐D switchable displays

Abstract— In this paper, the design of a lenticular‐based 2‐D/3‐D display for mobile applications is described. This display combines look‐around capability with good 3‐D resolution. In order to allow high‐resolution datagraphic applications, a concept based on actively switched lenses has been developed. A very noticeable problem for such displays is the occurrence of dark bands. Despite slanting the lenticular and defocusing the lens, banding becomes unacceptable when the display is viewed from an angle. As a solution, fractional viewing systems to reduce the banding intensity by almost two orders of magnitude is introduced. The resulting 3‐D display can be viewed from any horizontal direction without banding.     

基于二维轮廓序列的膝关节三维重建

提出了一个基于二维轮廓序列的四面体网格生成方法,用于医学图像三维几何模型重构.该方法首先对各选定的断层图像提取目标轮廓并做分支匹配等处理,然后生成各轮廓内部平面域的三角网格,最后在相邻断层之间根据三角网格连接四面体单元.该方法被应用于人体膝关节虚拟手术系统的三维几何建模,得到的膝部股骨模型包含494个节点和2 046个四面体单元,膝部脂肪模型包含2 854个节点和14011个四面体单元,这些模型被成功地应用于膝关节手术仿真,从而证明了该三维模型重建方法的可行性和有效性.     

一种辅助轮廓线的断层医学图像三维重建算法

针对轮廓线重建过程中的轮廓分叉问题,提出了一种改进的多轮廓线三维重建算法,通过构造辅助轮廓线将多轮廓线的连接转换为单轮廓线的连接,改进了利用多轮廓线进行三维重建的不足,利用可接受表面实现特征点的三角化,并根据曲率的变化拟合重建过程中的不光滑表面,进而实现断层医学图像的三维重建。实验结果证明,运用本算法在保证重建物体正确的同时,缩短了体数据的构造时间,加快了整个表面的重建速度。     

2‐D D3LS algorithm with mutual coupling

New adaptive algorithm of direct data domain is presented which can recover the signal in the presence of mutual coupling. The proposed algorithm can estimate the coupling coefficients without utilizing any auxiliary sensors. Numerical simulation shows that the proposed algorithm can accurately recover the signal in the presence of mutual coupling. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Depth‐ and viewing‐angle‐enhanced 3‐D/2‐D switchable display system with high contrast ratio using multiple display devices and a lens array

Abstract— An improved 3‐D/2‐D switchable display system with enhanced depth and viewing angle by adding two LCD panels to an integral imaging system has been realized. The proposed system uses the see‐through property of an LCD panel and displays multiple sets of elemental images on the LCD panels to integrate them on multiple locations simultaneously. As a result, the depth of the 3‐D image can be enhanced. For wide viewing angles, the time‐multiplexing method was adopted by displaying mask patterns on the front LCD panel. In addition, another technique to increase the contrast ratio of the proposed system has also been developed. Some experimental results will be provided.     

Flicker visibility and related visual discomfort in 3‐D displays with LED backlight

Abstract— In this paper, the perception of flicker in time‐sequential or field‐sequential 3‐D LC TVs driven by LED backlights is described. The seriousness of the perceived flicker and its influence on visual discomfort is investigated for various backlight operational modes. Results show that display backlights presenting different temporal light distribution have significant contribution to flicker visibility and visual discomfort. The display dimension, 2‐D or 3‐D, affects visual discomfort but not flicker visibility. The relationship between visual discomfort and flicker visibility is proportional when rendering 2‐D images, but not in the case of 3‐D images. Finally, a simple model is presented to evaluate visual discomfort related to flicker in 2‐D rendering.     

MUTED: Multi‐user 3‐D display

Abstract— Research described in this paper encompasses the design and building of glasses‐free (autostereoscopic) displays that utilize a direct‐view liquid‐crystal display whose backlight is provided by a projector and novel steering optics. This is controlled by the output of a multi‐user head‐position tracker. As the displays employ spatial multiplexing on a liquid‐crystal‐display screen, they are inherently 2‐D/3‐D switchable with 2‐D being achieved by simply displaying the same image in the left and right channels. Two prototypes are described in this paper; one incorporating a holographic projector and the other a conventional LCOS projector. The LCOS projector version addresses the limitations of brightness, cross‐talk, banding in the images, and laser stability that occur in the holographic projector version. The future development is considered and a comparison between the prototypes and with other 3‐D displays is given.     

机器人视觉三维重建网格门户的研究与开发

为了提高机器人视觉三维重建的速度,分析了建设机器人视觉三维重建网格的必要性以及网格门户在网格系统中的重要性.根据三维重建网格的特点设计了网格门户的体系结构,介绍了基于Gridport门户开发工具包快速开发三维重建网格门户中的各个组件的基本过程,实现了基于门户的单点登录、用户管理、资源监测、文件传输和三维重建服务调用等基本功能.     

Switching directional BLUs for full‐resolution auto‐stereoscopic 3D/2D and 2D/3D LCDs

Directional backlight unit (BLU) design concept was applied to realize full‐resolution field alternate auto‐stereoscopic liquid crystal displays (LCDs) with built‐in 3D/2D and 2D/3D. The application‐oriented BLU design requires priority in realizing 2D mode or 3D mode. The switching characteristic of BLU with two confronting illuminating sets was applied to build 2D mode into 3D display and 3D mode into 2D display. An LCD with 2D mode as primary function requires higher double‐sided luminance uniformity than 3D mode. On the other hand, an LCD with 3D mode requires higher single‐sided luminance uniformity than 2D mode. For increasing the double‐sided luminance uniformity for 2D mode as a primary function of the display, the former BLU design was realized by using uniform prismatic structure, that is, using uniform bilateral prismatic structure with a cross section of isosceles triangle on the back surface of the light‐guide plate. For increasing single‐sided luminance uniformity for 3D mode as a primary function of the display, the latter was realized by using graded angle design, that is, unilateral prisms with a cross section of a scalene triangle on the back surface of the light‐guide plate. The LCDs of small‐sized‐handheld game devices and still cameras were fabricated using the 3D/2D and 2D/3D displays.     

2‐D/3‐D displays based on switchable lenticulars

Abstract— An attractive concept for 3‐D displays is the one based on LCDs equipped with lenticular lenses. This enables autostereoscopic multiview 3‐D displays without a loss in brightness. A general issue in multiview 3‐D displays is their relatively low spatial resolution because the pixels are divided among the different views. To overcome this problem, we have developed switchable displays, using liquid‐crystal (LC) filled switchable lenticulars. In this way, it is possible to have a high‐brightness 3‐D display capable of fully exploiting the native 2‐D resolution of the underlying LCD. The feasibility of LC‐filled switchable lenticulars was shown in several applications. For applications in which it is advantageous to be able to display 3‐D and 2‐D content simultaneously, a 42‐in. locally switchable prototype having a matrix electrode structure was developed. These displays were realized using cylindrically shaped lenticular lenses in contact with LC. An alternative for these are lenticulars based on gradient‐index (GRIN) LC lenses. Preliminary results for such switchable GRIN lenses are presented as well.     

基于栅格模型的双目移动机器人三维场景重建

以投影几何学以及双目立体视觉原理为理论基础,对移动机器人的三维重建技术进行研究,对移动机器人漫道过程中所在的兴趣区域的场景进行较为精确的建模.设计了机器人的快速建模方法,利用迭代最近点算法(ICP),完成了多个局部三维场景模型的融合.同时,结合栅格投射理论,完成了对全局三维场景模型的更新.利用栅格模型重建的三维场景,具有环境信息丰富,模型描述精确的特点,可以应用于移动机器人导航领域.     

Dual‐lenticular‐lens‐based 2‐D/3‐D convertible autostereoscopic display

Abstract— A 2‐D/3‐D convertible display using two lenticular lenses has been developed. It shows 2‐D pictures in full resolution and 3‐D autostereoscopic pictures in half resolution by moving one lens relative to the other. The lens assembly consists of thin metal frames, two lenticular lenses, and two shape‐memory‐alloy (SMA) wires used as actuators. While this assembly is applicable to flat‐panel displays of any kind, its simple structure and low power consumption make it best suited to mobile terminals, such as PDAs and mobile phones. Here, we describe its structure and present evaluation results.     

基于CPLD的彩色视觉移动机器人路径跟踪系统

路径跟踪是机器人视觉导航控制基本技术之一,为使机器人沿地面彩色引导线自主运动,并能在适时离线执行任务后自动返航,提出了一种用可编程逻辑器件(CPLD)实现的视觉伺服PID控制方法.该方法利用图像特征反馈对其所跟踪的路经进行实时识别跟踪.仿真结果表明,该方法改善了控制算法的实时性,提高了移动机器人的路径跟踪精度与速度.