全局光照环境中的逆向绘制

提出一种恢复场景中所有物体的反射特性的方法.算法以一个全景图、场景的完整几何模型和光源信息为输入,结果是场景的一个完整反射模型.恢复是以逐步求精的方式进行的.先假定物体表面是漫反射面并生成一幅全景图,然后算法逐步迭代,比较绘制的全景图和原始全景图,如果有的物体的误差超过某个阈值,算法为他们选择更负责的反射模型.最后,场景中的每个物体有了一个合适的反射模型,可以在新的光照和视点条件下绘制,旧的物体可以从场景中移去,新的物体可以添加到场景中.对漫反射、各向同性反射和各向异性反射纹理面的纹理恢复也作了深入研究;高光和阴影的影响也能基本去除.     

基于球面全景图的虚拟场景实时漫游系统

设计并实现一种基于球面全景图的虚拟场景实时漫游系统。虚拟场景的实时漫游可以通过对球面全景图进行重投影完成。通过重投影球面全景图的可视部分到视平面上,可以生成虚拟场景在不同视线方向上的透视视图。使用球面全景图的重投影算法可以模拟相机的旋转运动,通过改变相机的视域,可以模拟相机的变焦运动。针对直接使用重投影不能满足球面全景图实时绘制的问题,在对球面全景图的重投影算法进行仔细分析的基础上,提出使用查找表和增量计算进行加速的策略。实验结果表明,优化后的系统能够对基于球面全景图的虚拟场景进行实时漫游     

Omnistereo: panoramic stereo imaging

An omnistereo panorama consists of a pair of panoramic images, where one panorama is for the left eye and another panorama is for the right eye. The panoramic stereo pair provides a stereo sensation up to a full 360 degrees. Omnistereo panoramas can be constructed by mosaicing images from a single rotating camera. This approach also enables the control of stereo disparity, giving larger baselines for faraway scenes, and a smaller baseline for closer scenes. Capturing panoramic omnistereo images with a rotating camera makes it impossible to capture dynamic scenes at video rates and limits omnistereo imaging to stationary scenes. We present two possibilities for capturing omnistereo panoramas using optics without any moving parts. A special mirror is introduced such that viewing the scene through this mirror creates the same rays as those used with the rotating cameras. The lens used for omnistereo panorama is also introduced, together with the design of the mirror. Omnistereo panoramas can also be rendered by computer graphics methods to represent virtual environments     

Panoramic appearance-based recognition of video contents using matching graphs

This paper proposes a general scheme for recognizing the contents of a video using a set of panoramas recorded in a database. In essence, a panorama inherently records the appearances of an omni-directional scene from its central point to arbitrary viewing directions and, thus, can serve as a compact representation of an environment. In particular, this paper emphasizes the use of a sequence of successive frames in a video taken with a video camera, instead of a single frame, for visual recognition. The associated recognition task is formulated as a shortest-path searching problem, and a dynamic-programming technique is used to solve it. Experimental results show that our method can effectively recognize a video.     

Real-time correction of panoramic images using hyperbolic Möbius transformations

Wide-angle images gained a huge popularity in the last years due to the development of computational photography and imaging technological advances. They present the information of a scene in a way which is more natural for the human eye but, on the other hand, they introduce artifacts such as bent lines. These artifacts become more and more unnatural as the field of view increases. In this work, we present a technique aimed to improve the perceptual quality of panorama visualization. The main ingredients of our approach are, on one hand, considering the viewing sphere as a Riemann sphere, what makes natural the application of Möbius (complex) transformations to the input image, and, on the other hand, a projection scheme which changes in function of the field of view used. We also introduce an implementation of our method, compare it against images produced with other methods and show that the transformations can be done in real time, which makes our technique very appealing for new settings, as well as for existing interactive panorama applications.     

基于立方体全景图的虚拟场景浏览技术研究及实现

虚拟现实技术将计算机采集到的各类信息以全新的方式组织起来,提供给用户一个趋于人性化的虚拟信息空间,如今通常以全景图象的方式来表示的虚拟场景主要有球面全景图、柱面全景图和立方体全景图3种模式.为了给用户浏览虚拟场景提供一种方便、自然的交互方式,提出了一种对立方体全景图进行实时交互浏览的基本重投影算法及其加速算法,并实现了一个立方体全景图浏览器,实验结果表明,该方法具有最大的观察自由度.     

Scanning scene tunnel for city traversing

This paper proposes a visual representation named scene tunnel for capturing urban scenes along routes and visualizing them on the Internet. We scan scenes with multiple cameras or a fish-eye camera on a moving vehicle, which generates a real scene archive along streets that is more complete than previously proposed route panoramas. Using a translating spherical eye, properly set planes of scanning, and unique parallel-central projection, we explore the image acquisition of the scene tunnel from camera selection and alignment, slit calculation, scene scanning, to image integration. The scene tunnels cover high buildings, ground, and various viewing directions and have uniformed resolutions along the street. The sequentially organized scene tunnel benefits texture mapping onto the urban models. We analyze the shape characteristics in the scene tunnels for designing visualization algorithms. After combining this with a global panorama and forward image caps, the capped scene tunnels can provide continuous views directly for virtual or real navigation in a city. We render scene tunnel dynamically by view warping, fast transmission, and flexible interaction. The compact and continuous scene tunnel facilitates model construction, data streaming, and seamless route traversing on the Internet and mobile devices.     

一种全景图浏览器的JAVA实现算法

全景图(panorama image)是近来出现在Internet上的一种新的交互式的虚拟场景表示方式，它以图像的方式再现了三维场景，可以用相应的浏览器实现虚拟场景的漫游，具有很好的真实感和沉浸感。本文详细介绍了这种全景图浏览器的实现原理，并给出了关键的JAVA代码。     

Robust detection and tracking of annotations for outdoor augmented reality browsing

A common goal of outdoor augmented reality (AR) is the presentation of annotations that are registered to anchor points in the real world. We present an enhanced approach for registering and tracking such anchor points, which is suitable for current generation mobile phones and can also successfully deal with the wide variety of viewing conditions encountered in real life outdoor use. The approach is based on on-the-fly generation of panoramic images by sweeping the camera over the scene. The panoramas are then used for stable orientation tracking, while the user is performing only rotational movements. This basic approach is improved by several new techniques for the re-detection and tracking of anchor points. For the re-detection, specifically after temporal variations, we first compute a panoramic image with extended dynamic range, which can better represent varying illumination conditions. The panorama is then searched for known anchor points, while orientation tracking continues uninterrupted. We then use information from an internal orientation sensor to prime an active search scheme for the anchor points, which improves matching results. Finally, global consistency is enhanced by statistical estimation of a global rotation that minimizes the overall position error of anchor points when transforming them from the source panorama in which they were created, to the current view represented by a new panorama. Once the anchor points are redetected, we track the user's movement using a novel 3-degree-of-freedom orientation tracking approach that combines vision tracking with the absolute orientation from inertial and magnetic sensors. We tested our system using an AR campus guide as an example application and provide detailed results for our approach using an off-the-shelf smartphone. Results show that the re-detection rate is improved by a factor of 2 compared to previous work and reaches almost 90% for a wide variety of test cases while still keeping the ability to run at interactive frame rates.     

三通道投影虚拟装配环境的研究与实现

在介绍基于3个通道投影的虚拟装配环境硬件结构的基础上，对该环境所涉及到的图像拆分技术以及同步机制进行了详细分析，提出了使用剖分视点透视投影空间进行虚拟装配环境场景图像拆分的方法，给出了三通道同步机制，并分析了虚拟装配环境中的同步消息类型．最后通过虚拟装配环境应用实例对上述方法进行了验证．     

Providing synthetic views for teleoperation using visual posetracking in multiple cameras

This paper describes a visual tool for teleoperative experimentation involving remote manipulation and contact tasks. Using modest hardware, it recovers in real time the pose of moving polyhedral objects, and presents a synthetic view of the scene to the operator of a teleoperated robot using any chosen viewpoint and viewing direction. To recover pose, the method of line tracking first introduced by Harris (1992) is extended to multiple calibrated cameras, and its dynamic performance improved using robust methods and iterative filtering. Experiments are reported which determine the static and dynamic performance of the vision system, and its use in teleoperation is illustrated in two experiments, a peg-in-hole manipulation task and an impact control task     

球面全景图漫游算法研究

基于图像的绘制技术不仅可以弥补传统基于几何绘制技术的不足。而且能给出更丰富的图像显示。基于实际应用出发,提出并实现了一种球面全景图的漫游算法。通过重投影球面全景图的可视部分到视平面上,可以生成虚拟场景在不同视线方向上的透视视图。针对直接使用重投影不能满足实时绘制的问题,提出了基于查找表的优化策略。     

Real-time panoramic video streaming system with overlaid interface concept for social media

In this paper, we propose a real-time panoramic video streaming system with overlaid interface concept for social media. The proposed system provides real-time panorama images for smart displays such as smart TVs, smart phones, and tablet PCs. Panorama images are collected at sporting events via panorama cameras. Contents thus collected are sent to servers and then provided to smart devices via live sports video streams. Users select a panorama camera and choose their viewing angle and zooming factor for the selected panorama camera. The proposed system provides immersive and realistic views of live sporting events on users’ displays. Furthermore, an overlaid panoramic interface concept is proposed for immersive live baseball watching combined with tightly integrated social media experience.     

基于图象的室内虚拟漫游系统

基于图象的绘制（Image Based Rendering)作为一种全新的图形绘制方式,以其相对于传统几何绘制而言,具有高效实用的优点,近年来得到了研究人员越来越多的关注,但IBR技术仍存在一些主要难点,如图象的无缝拼接和实时漫游。针对此问题,开发了一个基于部分球面模型的室内虚拟漫游系统。该系统采用自动匹配和人机交互相结合的方法,可以无缝地将多幅照片拼接成一张全景图,同时采用一种改进的基于查找表的算法,实现了固定视点的实时漫游。     

Railroad online: acquiring and visualizing route panoramas of rail scenes

A patrol type of surveillance has been performed everywhere from police city patrol to railway inspection. Different from static cameras or sensors distributed in a space, such surveillance has its benefits of low cost, long distance, and efficiency in detecting infrequent changes. However, the challenges are how to archive daily recorded videos in the limited storage space and how to build a visual representation for quick and convenient access to the archived videos. We tackle the problems by acquiring and visualizing route panoramas of rail scenes. We analyze the relation between train motion and the video sampling and the constraints such as resolution, motion blur and stationary blur etc. to obtain a desirable panoramic image. The route panorama generated is a continuous image with complete and non-redundant scene coverage and compact data size, which can be easily streamed over the network for fast access, maneuver, and automatic retrieval in railway environment monitoring. Then, we visualize the railway scene based on the route panorama rendering for interactive navigation, inspection, and scene indexing.     

一种圆柱形全景图生成新算法及其实现

利用基于图象的绘制(IBR)技术来建立具有真实感的虚拟环境是当前计算机图形学研究领域中的一项热门课题，也是虚拟现实技术中的关键技术。它以简单的图象合成代替基于三维几何的建模和渲染，加快了画面的显示速度，是建立特定三维场景的一种高效率的方法。基于这种方法，我们提出了一种生成圆柱形全景图的新算法，它通过快速查找
相邻两幅图象的匹配区域而实现图象的无缝拼接，建立圆柱形全景图。本算法计算速度快，效率高，能生成逼真的全景图。文章的最后给出了基于这种算法生成的部分全景图图实例。     

利用鱼眼技术构建全景漫游系统的方法探索

全景漫游系统是近来出现在Internet上的一种新的交互式的虚拟场景表示方式,它以全景图的方式再现了三维场景,可以用相应的浏览器实现虚拟场景的漫游,具有很好的交换性和真实感。该文就如何利用鱼眼镜头进行图像获取;如何对图像进行拼接制作球状360度全景图;如何构建基于Java applet的漫游系统的方法进行了探索。     

Real-time exploration and photorealistic reconstruction of large natural environments

This paper presents a hybrid (geometry- and image-based) framework suitable for providing photorealistic walkthroughs of large, complex outdoor scenes, based only on a small set of real images from the scene. To this end, a novel data representation of a 3D scene is proposed, which is called morphable 3D panoramas. Motion is assumed to be taking place along a predefined path of the 3D environment and the input to the system is a sparse set of stereoscopic views at certain positions (key positions) along that path (one view per position). An approximate local 3D model is constructed from each view, capable of capturing the photometric and geometric properties of the scene only locally. Then, during the rendering process, a continuous morphing (both photometric as well as geometric) takes place between successive local 3D models, using what we call a ‘morphable 3D model’. For the estimation of the photometric morphing, a robust algorithm capable of extracting a dense field of 2D correspondences between wide-baseline images is used, whereas, for the geometric morphing, a novel method of computing 3D correspondences between local models is proposed. In this way, a physically valid morphing is always produced, which is thus kept transparent from the user. Moreover, a highly optimized rendering path is used during morphing. Thanks to the use of appropriate pixel and vertex shaders, this rendering path can be run fully in 3D graphics hardware and thus allows for high frame rates. Our system can be extended to handle multiple stereoscopic views (and therefore multiple local models) per key position of the path (related by a camera rotation). In this case, one local 3D panorama (per key position) is constructed, comprising all local 3D models therein, and so a ‘morphable 3D panorama’ is now used during the rendering process. For handling the geometric consistency of each 3D panorama, a technique which is based on solving a partial differential equation is adopted. The effectiveness of our framework is demonstrated by using it for the 3D visual reconstruction of the Samaria Gorge in Crete.     

基于VR的驾驶仿真及安全教育系统开发

针对全国道路交通事故高发现状及传统驾驶安全教育方式单一、培训效果差的缺点,基于虚拟现实技术（VR）,在引发交通事故人为因素理论基础上,开发驾驶仿真及安全教育系统。系统基于Unity3D引擎,构建了基于道路实景数据的虚拟场景,并联合SUMO实现了道路交通流仿真,通过VR技术仿真驾驶环境及驾驶行为;基于碰撞检测原理,建立了关卡违规触发机制,编码自定义屏幕空间渲染方式模拟驾驶员视觉效果,并构建了基于图像的交通事故现场三维全景,从认知、感知层面培训驾驶员安全驾驶。实用性测试结果表明,系统实现了不同道路场景、气象条件与交通状况下的驾驶模拟及安全培训,增强了使用者的学习兴趣,提高了使用者驾驶安全素养,具有较强的实用性。