PTZ摄像机视频与三维模型的配准技术研究

针对基于投影纹理映射的虚实融合系统,提出了一种PTZ摄像机视频与三维模型实时配准的技术.选取PTZ摄像机若干特定姿态的子图像组成一张全景图像,进行最优匹配图像的搜索,用SURF图像配准的方法对实时视频图像进行透视变换,利用最优匹配图像的三维投影信息将实时视频图像精确投影到三维模型中.实验结果表明,该算法具有较高的准确性,适用于虚实融合系统中PTZ摄像机视频的三维配准.     

全景视频信息空间模型

全景视频是一种以３６０度实景全景图像为基础来构造虚拟环境的技术，本文讨论了利用它来建立一个可操作、可漫游的虚拟信息空间，并就如何建立该空间模型进行研究。该空间具有立体显示和三维虚拟声音，能够组织、存取、操作和表现多媒体空间数据。     

基于视差平面分割的移动机器人障碍物地图构建方法

作为自主移动机器人地表障碍物探测（GPOD）技术的一部分,提出了一种利用双目摄像机的视差图像 获取信息来构建机器人前方障碍物栅格地图的方法. 该方法融合了3 维立体视觉技术以及2 维图像处理技术,前者 依据视差图的直方图信息对视差图像进行自适应平面分割,把每个平面看作是3 维场景中的实物切片进而提取障碍 物3 维信息,后者通过计算各平面上的障碍物信息曲线来提取障碍物信息,把立体视觉数据从视差图像空间变换到 2 维的障碍物地图空间. 给出了该方法构建障碍物地图的整体过程,试验结果证明了该算法的有效性和精确性.     

大视场视频全景图快速生成方法

针对视频图像拼接中配准误差的积累问题,提出一种适合大面积静态场景观测的视频全景图快速生成方法,包括摄像机在一维单幅扫描方式和二维多幅扫描方式下的视频全景图的直接拼接算法。实验结果表明,无论摄像机工作在单幅方式还是多幅方式下,该方法都可以快速、准确地拼接出较高质量的视频全景图像,能有效避免局部配准误差的积累与传播,并解决一般全局配准算法复杂费时的问题。     

PTZ自主跟踪中的全景视频生成

提出了一种在单PTZ摄像机自主跟踪过程中生成全景视频的方法。该方法在自主跟踪目标的同时,生成目标在大场景上运动的全景视频,可应用于PTZ摄像机监控场所。该方 法将全景视频看作全景背景图像和当前目标图像的叠加：首先利用Mean Shift跟踪方法逐帧获取目标区域图像并保存;然后利用相邻两帧视频图像的竖直方向投影匹配和Harris角 点匹配结果合成全景背景,与传统的配准方法相比,大大降低了匹配运算的复杂度,使全景背景的生成能够实时进行,并记录每帧图像到背景图像的变换参数;最后逐帧将目标区 域图像变换到背景图像上得到全景视频。本文方法与传统的全景视频生成方法相比,无需人工控制摄像机的转动,也无需手工对齐视频帧,整个过程全部自动完成。     

一种移动设备视频全景并行生成技术*

通过移动摄像机合成视频全景图,由于视频中存在时间冗余以及现有合成技术对大角度旋转存在失配,提出一种鲁棒性较好的视频全景并行合成方法。该方法首先对选取的关键帧采用并行线程提取可重复性特征,并利用特征估计透视运动模型,从而对相邻关键帧进行全局配准;然后对重叠区域进行双线性融合,以减少视差对重叠场景的影响,同时并行优化提高了视频全景的合成速度。不同条件下移动合成实验表明,在大角度移动旋转以及视差等情况下仍能较好地合成视图。     

视频图像在三维模型中的渲染

视频监控是大型安防工作中最重要的一个环节,传统的视频监控系统展示给用户的只是独立的二维平面图像,图像脱离环境,整体性不足,为了解决该问题,提出了将视频图像渲染显示于三维模型的思路.研究了纹理映射技术并结合视频图像渲染的特殊性分析研究了Z缓冲算法、Shadow map算法,根据实际应用提出Extend Shadow map算法以实现将视频图像与三维场景无缝贴合.实验结果表明,视频图像渲染显示于三维模型中所体现的优越性.     

全景视频的信息组织和实现方法

全景视频不是一般意义的虚拟现实，它提供了一种新型的时空信息组织形式。这种基于实景图像的全景视频，具有广阔的应、用前景和研究价值．本文介绍了全景视频的概念和表现方式，以及利用全景视频技术来构造虚拟现实环境的方法，并提出了实现全景视频的具体方法步骤。     

基于立体视觉的立体拍摄参数自动获取方法

现有的3D摄像机在立体拍摄过程中参数调整困难,难以保证左右2台摄像机动作的协调性和一致性。针对该问题,提出一种基于立体视觉的立体拍摄参数自动获取方法。由4台全方位视觉传感器构成的全景3D摄像机获取全景立体图像,通过立体图像处理技术自动获取立体拍摄所需要的汇聚点位置、拍摄距离、焦距以及光圈系数等参数。实验结果表明,该方法能有效保证焦距、拍摄方向、拍摄角度和3D深度等3D拍摄参数的一致性,解决3D拍摄过程中2台摄像机在拍摄动作以及立体景深参数调整等协调难的问题,在拍摄3D全景视频图像的同时进行3D特写视频图像的拍摄,实现在显示器上全景点控的自动3D特写视频图像拍摄。     

基于自由立体视频的露天开采虚拟现实的研究与实现

文章结合最新的交互式自由立体视频技术与露天开采虚拟现实技术,设计并实现了一种基于自由立体视频的露天矿开采虚拟现实技术的交互与演示系统。文章利用3DS Max和VRMap软件建立了某露天矿区的虚拟视觉模型,并将这些虚拟视觉模型按照适合立体显示的条件进行场景渲染和视频图象生成,最后结合虚拟场景的三维显示特性设计了交互式自由立体视频软件,通过该软件展示了虚拟现实场景。该系统克服了传统虚拟现实演示的局限性,用较低的成本支持更多的用户进行参与和交互,同时也具有较强的环境拓展性。     

Cylindrical panoramic mosaicing from a pipeline video through MRF based optimization

Stratum structure detection is a fundamental problem in geological engineering. One of the most commonly employed detection technologies is to shoot videos of a borehole using a forward moving camera. Using this technology, the problem of stratum structure detection is transformed into the problem of constructing a panoramic image from a low quality video. In this paper, we propose a novel method for creating a panoramic image of a borehole from a video sequence without the need of camera calibration and tracking. To stitch together pixels of neighboring image frames, our camera model is designed with a focal length changing feature, along with a small rotational freedom in the two-dimensional image space. Our camera model assumes that target objects lie on a cylindrical wall and that the camera moves forward along the central axis of the cylindrical wall. Based on these two assumptions, our method robustly resolves these two degrees-of-freedoms in our camera model through KLT feature tracking. Since the quality of the result video is affected by possible illumination overflow, camera lens blurring, and low video resolution, we introduce a cost function for eliminating seams between stitching strips. Our cost function is designed based on Markov Random Field and optimized using a belief propagation algorithm. Using our method, we can automatically construct a panorama image with good resolution, smoothness, and continuousness both in the texture and illumination space. Experiment results show that our method could efficiently generate panoramas for long video sequences with satisfying visual quality.     

采用视频拼图方法构建高分辨率全景视频监控系统

与普通视频监控系统只能实现单向监控不同,全景视频监控系统可以实现360°全向监控。设计并实现了一种嵌入式高分辨率全景视频监控系统KD-PVS。重点介绍了KD-PVS中多个摄像头的空间位置设计、视频图像变换与拼接算法。KD-PVS通过对多个摄像头采集的视频进行实时变换与拼接以生成全景视频。该系统可方便应用于金融系统、仓库、监狱和移动监控等多种场合,尤其适用于室内监控。     

改进格雷码结构光双目视觉工件3D测量

机器人喷涂、焊接、研磨等现代制造过程,通常需要获取工件3D几何形状信息以实现路径自动规划。针对此需求,提出了一种改进灰度编码的结构光双目视觉成像与三维测量系统。在离线标定获得相机参数的基础上,采用黑白反向重投影方法解决传统格雷码结构光成像中边界模糊问题;同时,提出快速区域块搜索算法,用于立体匹配和视差图生成;最后,采用Lanczos插值算法填补遮挡造成的视差图空白,从而获得完整的深度信息,实现工件高精度3D重建。实际工件成像实验结果表明：该方法能够实现工件快速、高精度三维重建,尤其对无纹理和弱纹理目标能获得较好的结果,能够满足工业环境测量需求。     

基于深度图压缩的边界自适应上采样方案

在三维视频系统中,为了更好地保护深度图的锐利边界并改善虚拟视图的合成质量,提出一种新的边界自适应性上采样方案来恢复由于在编码前进行下采样操作而丢失的深度信息。通过Sobel算子识别出低分辨率深度图和高分辨率纹理图的水平边界和垂直边界。根据深度图不同区域的特点利用纹理信息来指导高分辨率深度图的重建。实验结果表明本文方法在提高了编码效率的同时也改善了合成视图的视觉效果。     

OpenGL中模拟目标与实时场景的融合技术

为了使视景仿真达到实时性和逼真性的双重要求,介绍了一种基于实时视频的真实背景与仿真模型进行融合的仿真场景实现技术.使用视频应用程序软件工具包VFW(Video for Windows)捕获实时视频形成真实纹理,在OpenGL仿真系统中将真实纹理代替传统的三维背景建模,建立了飞机在高空俯视地面的具有层次变化的仿真场景.实验证明这种方法不但简化了视景仿真步骤,节省了背景建模时间,而且增加了逼真度,易于实现场景的快速仿真.     

Video Source Identification Algorithm Based on 3D Geometric Transformation

Digital video has become one of the most preferred ways for people to share information. Considering people tend to release illegal information in anonymous way, the problem of video source identification attracts more and more attention as an important part of multimedia forensics. The Photo-Response Non-Uniformity (PRNU) based algorithm shows to be a promising solution for the problem of video source identification. However, it is necessary to make a geometric transformation for testing PRNU noise to align it with the reference noise, due to the effect of video stabilization. This paper analyzes the three-dimensional (3D) characteristics of camera jitters and studies how to estimate the parameters of 3D geometric transformation when aligning PRNU noises between reference and test. In the algorithm design, quaternion is used to transform PRNU noise image in 3D space, and 15 rotation axes of 3D space are estimated for experiments. 162 videos of 9 smart phones were tested. Most of the videos got a higher peak to correlation energy (PCE) value by using this algorithm, and showed better results when applied to videos with complex texture. The experiment part also records the geometric transformation parameters of the PRNU noise which need to map from image domain to video domain.     

H．264兼容的全景视频编码方法

在拍摄全景视频时,摄像头往往仅在水平方向上移动。由于在水平移动中偶尔有轻微的上下抖动,以及传感器采集引入的噪声,直接对其进行H.264编码,编码效率不高。针对全景视频拍摄和H.264编码的特点,提出了一种对全景视频高效的H.264编码方法,首先将原始全景视频合成一张全景图;然后再把全景图直接转换为标准H.264码流。实验结果表明,采用该方法对其编码,与直接编码原始视频相比,编码效率大大提高。     

Virtual view synthesis of people from multiple view video sequences

This paper addresses the synthesis of novel views of people from multiple view video. We consider the target area of the multiple camera 3D Virtual Studio for broadcast production with the requirement for free-viewpoint video synthesis for a virtual camera with the same quality as captured video. A framework is introduced for view-dependent optimisation of reconstructed surface shape to align multiple captured images with sub-pixel accuracy for rendering novel views. View-dependent shape optimisation combines multiple view stereo and silhouette constraints to robustly estimate correspondence between images in the presence of visual ambiguities such as uniform surface regions, self-occlusion, and camera calibration error. Free-viewpoint rendering of video sequences of people achieves a visual quality comparable to the captured video images. Experimental evaluation demonstrates that this approach overcomes limitations of previous stereo- and silhouette-based approaches to rendering novel views of moving people.     

User interface for video observation over the internet

This paper presents the design and application of a system for live video transmission and remote camera control over the World Wide Web. Extensive testing of the Internet Video Server (IVS) prompted us to improve its user interface. The GlobalView extension of IVS was developed which enables the generation of panoramic images of the environment and a more intuitive control of the camera. The live video frame is superimposed on a 360^°static panoramic picture. By interactively moving a rectangular frame in the panoramic picture, the user locally selects the new direction of the camera. Once the view is selected the users prompts the selection and the command is issued over the Internet to the remotely-controlled camera. The static panoramic image is constantly updated in areas where new live video information gets available. Two methods are described for static panoramic image generation: one uses geometric transformation and the other is the brute-force scanning approach. We discuss how visual summaries of activities on an observed location can be generated and custom queries made with a similar intuitive user interface.