光栅式自由立体显示技术的研究与分析

近年来在三维立体显示技术中,我们正经历着从眼镜式三维显示到自由式三维图像显示的跨越。本文通过分析人的立体视觉,阐述了基于双目视差原理实现左右眼视频图像分离的光栅式自由立体显示技术的具体工作原理及分析。     

基于SIFT 匹配的多视点立体图像零视差调整

针对目标跟踪过程中目标可能出现的快速变化和严重遮挡等问题,提出了一种基于新的子空间表示的目标跟踪算法。采用距离不变量对尺度不变特征变换(SIFT)特征点匹配对进行提纯。用提纯后的特征点匹配对,通过线性拟合得到仿射变化参数。在粒子滤波的理论框架下,采用快速的迭代算法,建立目标的主分量(PCA)子空间表示,结合计算得到的仿射变化参数,构造有效的目标观测模型完成跟踪。同时,采用在线学习的方法对SIFT特征点和PCA子空间进行定时更新。大量实验表明,提出的算法能快速有效地完成对姿态和形状剧烈变化的目标的精确跟踪。     

采用光栅的立体图像显示

近年来,有关动态立体图像显示系统的报道非常多.研究人员采用光栅(衍射光栅)阵列和液晶显示(LCD)相组合的简单结构,研制出无需眼镜可以多视差同时显示的动态立体图像显示系统(三维视频系统).该系统可以同时显示多方位全色视差图像,观看者无需选择视点位置,即可观看到全色立体图像.1 工作原理采用衍射光栅的三维视频系统的立体图像显示,在原理上实现了在各个不同的方向可以显示与各个方向相对应的视差图像.这种方法,通过增加视差图像的个数,一旦使视点移动,便可观察到转过来的图像,具有更自     

不同颜色空间多视点视频颜色校正的性能分析

在简述几种颜色空间及多视点视频线性颜色校正方法的基础上,利用多视点视频线性颜色校正方法对不同序列分别在3个颜色空间(CIELab,RGB,YUV)中进行校正,从客观的视差平均值计算和主观评价质量两个方面对校正效果进行比较.实验结果表明,序列两视点所在的空间中的直图表述差异越大,则在此空间中进行颜色校正的效果越好.     

分布式多视点视频编码中的立体边信息生成

新兴的分布式多视点视频编码通过在解码端使用立体边信息可充分挖掘传统单视点的时间相关性和多视点特有的视间相关性.研究了一种多视点运动预测的立体边信息生成算法,提出了近似视差估计和编码端掩模融合算法.实验证明,解码端采用近似的视差矢量,编码端传递某些先验信息,都能有效提高立体边信息精度,降低计算复杂度.     

一种多视点视频中的对象提取方法

提出一种自由视点电视的对象提取方法,首先用Birchfield算法进行快速的视差估计方法得到一个较为平滑的视差图,然后对初始的分割结果用形态学滤波,实验结果证明了所提出方法的有效性和可靠性。     

基于多视点立体角度模型的相关研究

多视点立体视角是FTV(Free-viewpoint TV)多视点采集/立体显示的关键因素,该文建立了多视点立体视角的数学模型。根据此模型获得了制约立体角度的相关因素,并定量模拟出用水平摄像机阵列拍摄物体时,拍摄距离与立体视角的关系;进一步根据人眼最大融合极限求出可防止产生重影、双轮廓的最大立体角与拍摄距离和观看距离之间的关系。最后导出立体角度与视点数之间的制约关系。仿真实验验证了所得结果的正确性。该文结果可为优化自由视点多视采集/立体显示系统提供理论依据。     

3D多视点立体显示及其关键技术

作为基于 DTV/HDTV 的二维(2D)显示之后的下一代视频显示技术,三维(3D)多视点立体显示已成为国际上的研究热点之一.为建立多视点立体显示系统,阐述了相关的关键技术,包括:光场表示模型和光场获取系统、高效的与现行视频标准兼容的多视点编码和传输方法、解码端任意位置视点的高效绘制方法、3D显示技术以及多视点自由立体显示.针对上述关键技术,分析了当前国际上的发展趋势及存在的问题,同时提出了一种基于交互式自由立体显示的 3D 视频处理系统的解决方案.     

多视点视频中基于乘加误差模型的亮度和色差校正

由于相机性能的差异,多视点视频序列之间总是存在亮度和颜色的差异,这种差异会影响多视点视频压缩和显示等后续处理过程的性能.本文由此提出了一种适用于多视点视频的亮度和色差(亮色度)校正算法.根据相机成像原理,不同相机的亮色度差异可以归类为乘性误差和加性误差.灰度级偏移,相机电子元件的放大和量化因子差异等都可以由乘加误差模型表示.为降低计算复杂度,本文采用直方图形状匹配的方法计算乘加误差模型的参数.该算法可作为多视点视频系统中的预处理过程,实验结果表明,该算法能够有效地提高后续压缩过程的性能.     

基于多视点视频的虚拟会议显示与合成

构造能够支持与会者群组间自然方式交流与交互的虚拟会议人机交互环境是虚拟会议要解决的核心问题.本文介绍了建立半沉浸的投影显示设备构造虚拟环境的方法,能够实现与会者之间空间位置的重构;提出了基于水线的视频对象分割算法,能够稳定地从虚拟会议静态背景环境实时提取与会者对象,以及基于位置的多视点视频重构合成方法.     

移动电话组件技术

由于半导体技术的大幅提高,现在移动电话的功能远远超越10年前的机型,而且体积与价格也大幅降低。现代手机中的硬件电路仍包含射频(RF)、基带以及功率管理等组件,新旧手机之间的差异体现在集成度和额外组件上,例如多媒体应用处理、相机、MMS、彩屏、FM收音机、MP3、游戏、GPS全球定位系统以及各种连网技术。随着移动电话     

Motion stereo for mobile robots

A method allowing a mobile robot to measure accurately its distance from external objects is introduced. It only requires a single uncalibrated camera and a dynamic vision system. The method was evaluated in an optical laboratory and also in outdoor-experiments. Even in outdoor-experiments with a vehicle moving at a speed of 30 km/h, errors of less than 1% of the true distance were achieved in real time. The accuracy achievable with the method depends on the nature of the image features used as a basis for the measurement. Laboratory experiments have been performed to investigate quantitatively the characteristics of the feature detectors under conditions of reduced lighting and, consequentially, reduced SNR, and with image features not matching the feature detectors perfectly. The best results can be achieved by using edge-like features. Point-like features do have certain desirable characteristics, but point detectors are more sensitive to noise than edge detectors. Hence, the accuracy achieved with corner detectors was less than the one achieved with edge detectors. Nevertheless, even with corner detectors the resulting error was less than 1%, despite the fact that the image of the target object did not contain good corners     

Multiband internal antenna for mobile phones

A new internal antenna for multiband cellphones comprises a U-shaped elongated flat conductor featuring a closed meandered slot, a ground and a feed leg. A benchmark on a Motorola T192 handset is conducted to illustrate the operation of this structure - called a folded inverted conformal antenna showing significantly more radiating bandwidth than a conventional dual-band PIFA.     

Nine-band antenna system for mobile phones

A physically and electrically small system of antennas, installed at the top of a 'monoblock' or 'bar' phone, is presented. The antennas cover nine bands - five cellular bands, the GPS and Bluetooth/WiFi bands and two future mobile TV bands.     

Robust multi-view stereo synthesized by various parameters model

In this paper, we have developed a novel and robust framework of combining a matrix splitting with multi-view stereo reconstructions to separate reconstruction inaccuracies from a various parameters model for high-accuracy multi-view stereo reconstruction. Instead of performing the fixed parameters reconstruction procedure, we apply the variational based 3D reconstruction algorithm multi-times with various parameters to derive a set of hypothetic 3D models, and then synthesized the final result by formulating the problem as a low-rank matrix splitting problem. Benefited from the matrix splitting formulation, the outliers and bad matches, which are treated as the noise in the synthesized model, are effectively removed and thus lead to a 3D reconstruction with higher accuracy than the existing fixed parameters reconstructions. Constrained convex optimization is introduced for matrix splitting with an accelerated proximal gradient (APG) algorithm integrated for fast convergence. Both the experiments on the Middlebury and real-world data sets have demonstrated the effectiveness of the proposed method.     

All-digital PLL and transmitter for mobile phones

We present the first all-digital PLL and polar transmitter for mobile phones. They are part of a single-chip GSM/EDGE transceiver SoC fabricated in a 90 nm digital CMOS process. The circuits are architectured from the ground up to be compatible with digital deep-submicron CMOS processes and be readily integrateable with a digital baseband and application processor. To achieve this, we exploit the new paradigm of a deep-submicron CMOS process environment by leveraging on the fast switching times of MOS transistors, the fine lithography and the precise device matching, while avoiding problems related to the limited voltage headroom. The transmitter architecture is fully digital and utilizes the wideband direct frequency modulation capability of the all-digital PLL. The amplitude modulation is realized digitally by regulating the number of active NMOS transistor switches in accordance with the instantaneous amplitude. The conventional RF frequency synthesizer architecture, based on a voltage-controlled oscillator and phase/frequency detector and charge-pump combination, has been replaced with a digitally controlled oscillator and a time-to-digital converter. The transmitter performs GMSK modulation with less than 0.5/spl deg/ rms phase error, -165 dBc/Hz phase noise at 20 MHz offset, and 10 /spl mu/s settling time. The 8-PSK EDGE spectral mask is met with 1.2% EVM. The transmitter occupies 1.5 mm/sup 2/ and consumes 42 mA at 1.2 V supply while producing 6 dBm RF output power.     

Investigating text input methods for mobile phones

Human Computer Interaction is a primary factor in the success or failure of any device but if an objective view is taken of the current mobile phone market you would be forgiven for thinking usability was secondary to aesthetics. Many phone manufacturers modify the design of phones to be different than the competition and to target fashion trends, usually at the expense of usability and performance. There is a lack of awareness among many buyers of the usability of the device they are purchasing and the disposability of modern technology is an effect rather than a cause of this. Designing new text entry methods for mobile devices can be expensive and labour-intensive. The assessment and comparison of a new text entry method with current methods is a necessary part of the design process. The best way to do this is through an empirical evaluation. The aim of the paper is to establish which mobile phone text input method best suits the requirements of a select group of target users. This study used a diverse range of users to compare devices that are in everyday use by most of the adult population. The proliferation of the devices is as yet unmatched by the study of their application and the consideration of their user friendliness.     

Are mobile phones safe?

Driven in part by disturbing allegations, a new wave of research in the United States and elsewhere is exploring possible links between cell phone radiation and cancer. Brain cancer, the topic of this article, is not the only health concern, but it dominates public discussion. A substantial body now exists of pertinent scientific evidence. This article discusses EM fields and research on looking for a link between them and cancer. The results of animal studies are briefly outlined. The article discusses exposure limits to RF radiation