一种基于频域相关技术的柱面全景图生成方法

在虚拟全景空间的构建中,360°柱面全景图象拼接是一项关键技术。该文通过对拍摄的实景图象做快速傅立叶变换,利用图象互功率谱的相位信息来实现全景图象的拼接,实验表明该方法大大提高了拼接速度,并且能够有效地克服图象间光照变化对拼接的影响,是一种快速实用的全景图拼接方法。     

Stability of invariant regions for an alternating direction method for systems of nonlinear reaction-diffusion equations

In this paper, we consider an alternating direction method for the numerical solution of systems of nonlinear reaction-diffusion equations, with homogeneous Dirichlet boundary conditions, and we consider some properties of the difference scheme. If the system admits a bounded invariant regionS of the phase space, we prove that, under certain conditions on the mesh,S is also invariant for the difference equations. Moreover we find an error bound which tends to diamS ast→+∞ and which is 0 (h) fort fixed. Finally, we derive a time-independent error bound for a special case of mild nonlinearity. Work performed under the auspicies of G.N.I.M.-C.N.R. in the context of Program of Preventive Medicine (Project MPP1), C.N.R.     

一种多尺度PHOG特征和最优缝合线的运动场景图像拼接算法

针对运动物体对图像拼接易造成配准误差和合成鬼影的问题,提出一种多尺度PHOG特征和最优缝合线的运动场景图像拼接算法。首先,在多尺度空间角点检测的基础上,引入分层梯度方向直方图(PHOG)描述方法,生成多尺度PHOG特征,进行稳定配准,避免运动物体的局部影响。然后,通过构建能量函数,采用图割算法搜索几何、灰度差异最小的缝合线,去除运动鬼影。实验结果表明,该方法对存在运动物体的场景拼接具有较高的拼接精度,拼接效果良好。     

Rapid omnidirectional vision acquisition using an intelligent linear scanning technique

Many computer vision applications can benefit from omnidirectional vision sensing, rather than depending solely on conventional cameras that have constrained fields of view. For example, mobile robots often require a full 360 view of their environment in order to perform navigational tasks such identifying landmarks, localizing within the environment, and determining free paths in which to move. There has been much research interest in omnidirectional vision in the past decade and many techniques have been developed. These techniques include: (i) catadioptric methods which can provide rapid image acquisition, but lack image resolution; and (ii) mosaicing and linear scanning techniques which have high image resolution but typically have slow image acquisition speed. In this paper, we introduce a novel linear scanning panoramic vision system that can acquire panoramic images quickly with little loss of image resolution. The system makes use of a fast line-scan camera, instead of a slower, conventional area-scan camera. In addition, a unique coarse-to-fine panoramic imaging technique has been developed that is based on smart sensing principles. Using the active vision paradigm, we control the motion of the rotating camera using feedback from the images. This results in high acquisition speeds and proportionally low storage requirements. Experimentation has been carried out, and results are given. Correspondence to: M.J. Barth (e-mail: barth@ee.ucr.edu)     

基于三维全景图的校园漫游系统王绪宛,雷蕾

虚拟现实是利用电脑模拟产生一个三维空间的虚拟世界,让使用者如同身历其境,而三维全景图是虚拟现实中一种重要的场景表示方法,生成三维全景图最简单的方法是直接使用全景相机等工具拍摄全景图,由于相机设备价格昂贵,限制了普遍使用;基于图像拼接技术对图像序列进行处理后生成全景图的低成本方法。该方法在南阳理工学院虚拟校园系统中使用,实现了虚拟校园的实景漫游,大大降低了成本。     

基于全局拼接的航拍图像拼接算法研究

研究航拍图像的拼接问题,提高图像拼接的准确度。由于当通过航拍获取的图像中部分图像相互存在重叠区域的比例不大时,造成拼接不准确。传统的区域的图像拼接算法无法将具有较小重叠区域的图像准确拼接。为了提高航拍图像拼接的准确率,提出一种全局的图像拼接算法,通过使用SIFT算法提取图像的SIFT特征点,根据位置误差最小的原则完成两幅图像的SIFT特征点匹配,最后利用整体最优化方法对拼接结果进行优化,采用全局特征点的拼接方法,可避免传统方法只利用重叠区域灰度特征而不能准确拼接低重叠度图像的问题。实验证明,改进方法利用图像的全局信息,准确地实现图像的拼接,取得了满意的结果。     

基于FPGA+GPU的图像采集处理系统设计

随着嵌入式图像处理系统的快速发展,对于前端图像采集模块的需求越来越高。图像采集的速度、分辨率、可靠性以及集成度对后续设计的准确度由极大的影响。通过对数字图像采集系统进行研究,设计出了基于FPGA和GPU架构的图像采集处理系统,重点研究了图像采集处理系统的硬件设计过程和软件设计过程。在基于FPGA+GPU的图像采集处理系统中,让具有强大运算处理能力的GPU专注于数据存储、用户交互以及后续的图像处理。系统中,FPGA则负责图像的采集、外设控制、任务调度。GPU与FPGA之间通过高速PCIE总线进行通信,分别设计编写基于Linux系统的驱动程序和FPGA端PCIE程序。实验结果表明,所设计基于FPGA+GPU的图像采集处理系统可实现437.5Mbps的实时图像采集存储速度,传输过程实时稳定,数据传输完整。     

A novel machine vision application for analysis and visualization of confocal microscopic images

In this paper, a novel machine vision application is presented for analyzing and visualizing confocal microscopy images of biological preparations. The proposed system is divided into three subsystems: a 3D curved surface extraction subsystem that generates 3D surfaces passing through selected key points in confocal image stacks; a 2D image projection subsystem that produces a flattened projection of the extracted curved surface; and an image mosaic subsystem that concatenates a series of image projections to form a view of an entire biological preparation. A combination of cubic interpolation and boundary matching is employed to reconstruct the 3D curved surface that passes through selected key points. The projection process integrates data fidelity and local smoothness constraints, producing a color or intensity projection along the desired 3D surface. Registration is achieved by aligning and minimizing the sum of the squared distances (SSD) between the intensities of the corresponding pixels. Two biological applications of the proposed system are reported to illustrate how the vision system could aid in biological research.Received: 18 August 2003, Accepted: 18 March 2004, Published online: 4 November 2004 Correspondence to: David M. Chelberg     

相控阵三维声纳数据离线可视化处理系统

设计并实现一种相控阵三维声纳图像的离线数据处理系统,并进行可视化建模.系统中精确配准采用最近点迭代配准,结合外围点消除法,通过拟牛顿进行最优化.拼接融合及多帧再重建采用多缀分辨率,同时支持低精度的快速显示和高精度的精细显示.测试结果证明,该系统能较好地实现相控阵三维摄像声纳图像的处理及可视化.     

基于2D格状图的显微图像拼接

针对大规模显微图像的拼接,提出了一种显微图像拼接的全局对准模型。利用2D格状图表示图像的邻接关系,并根据局部对准的可靠性对格状图进行修正,以消除空白区的影响。根据图像投影坐标的误差建立全局对准模型,可以有效地消除误差积累。把系统偏斜校正作为约束条件加入全局对准模型,并利用非线性优化方法得到具有全局一致性的图像对准参数,成功地解决了大规模显微图像的拼接问题。     

An efficient method for geo-referenced video mosaicing for environmental monitoring

Environmental monitoring applications require seamless registration of optical data into large area mosaics that are geographically referenced to the world frame. Using frame-by-frame image registration alone, we can obtain seamless mosaics, but it will not exhibit geographical accuracy due to frame-to-frame error accumulation. On the other hand, the 3D geo-data from GPS, a laser profiler, an INS system provides a globally correct track of the motion without error propagation. However, the inherent (absolute) errors in the instrumentation are large for seamless mosaicing. The paper describes an effective two-track method for combining two different sources of data to achieve a seamless and geo-referenced mosaic, without 3D reconstruction or complex global registration. Experiments with real airborne video images show that the proposed algorithms are practical in important environmental applications. Zhigang Zhu received his B.E., M.E. and Ph.D. degrees, all in computer science from Tsinghua University, Beijing, in 1988, 1991 and 1997, respectively. He is currently an associate professor in the Department of Computer Science, the City College of the City University of New York. Previously, he was an associate professor at Tsinghua University, and a senior research fellow at the University of Massachusetts, Amherst. His research interests include 3D computer vision, HCI, virtual/augmented reality, video representation, and various applications in education, environment, robotics, surveillance and transportation. He has published over 90 technical papers in the related fields. He is a member of IEEE and ACM. Edward M. Riseman received his B.S. degree from Clarkson College of Technology in 1964 and his M.S. and Ph.D. degrees in electrical engineering from Cornell University in 1966 and 1969, respectively. He joined the Computer Science Department at UMass-Amherst as assistant professor in 1969, has been a professor since 1978, and served as chairman of the department from 1981 to 1985. Professor Riseman has conducted research in computer vision, artificial intelligence, learning, and pattern recognition, and has more than 200 publications. He has co-directed the Computer Vision Laboratory since its inception in 1975. Professor Riseman has been on the editorial boards of Computer Vision and Image Understanding (CVIU) from 1992 to 1997 and of the International Journal of Computer Vision (IJCV) from 1987 to the present. He is a senior member of IEEE, and a fellow of AAAI. Allen R. Hanson received his B.S. degree from Clarkson College of Technology in 1964 and his M.S. and Ph.D. degrees in electrical engineering from Cornell University in 1966 and 1969, respectively. He joined the Computer Science Department at UMass-Amherst as an associate professor in 1981, and has been a professor there since 1989. Professor Hanson has conducted research in computer vision, artificial intelligence, learning, and pattern recognition, and has more than 150 publications. He is co-director of the Computer Vision Laboratory at UMass-Amherst, and has been on the editorial boards of the following journals: Computer Vision, Graphics and Image Processing 1983–1990, Computer Vision, Graphics, and Image Processing—Image Understanding 1991–1994, and Computer Vision and Image Understanding 1995–present. Howard Schultz received a M.S. degree in physics from UCLA in 1974 and a Ph.D. in physical oceanography from the University of Michigan in 1982. Currently, he is a senior research fellow with the Computer Science Department at the University of Massachusetts, Amherst. His research interests include quantitative methods for image understanding and remote sensing. The current focus of his research activities are on developing automatic techniques for generating complex, 3D models from sequences of images. This research has found application in a variety of programs including real-time terrain modeling and video aided navigation. He is a member of the IEEE, the American Geophysical Union, and the American Society of Photogrammetry and Remote Sensing.     

病理切片远程会诊中图像拼接技术的研究

研究图像拼接技术优化问题,是当前图像处理领域的研究热点。由于技术原因,在拼接时会造成误配。目前有利用全局优化的拼接方法进行修正的,理论上比较合理,但在速度和效果方面,尤其是精度要求比较高的场合还不理想。为解决上述问题,提出一种新方法,根据图片拼接时位置之间的相关性进行修正。提出拼接参数的相关公式,分析并提出修正简化规律。最后对十六张病理切片拼接图中误配部分进行修正。实验证明,算法可以将误差控制在一个像素以内,取得良好的效果。证明方法适用于对拼接精度要求高的应用领域,有较高的实用价值。     

基于最小路由代价树的大规模显微图像拼接方法

为了对大规模显微图像进行高质量的拼接,首先提出拼接图的概念及获得高质量全景图像的3个原则,然后采用分块-空间聚类算法配准相邻图像,同时评估配准质量,并计算拼接图的边的权值;最后在此基础上,提出了一种基于最小路由代价生成树的图像拼接方法,该方法通过计算拼接图的最小路由代价生成树来确定所有图像的全局位置,并用来生成全景图像。实验结果表明,该方法可获得高质量的全景图像。     

基于复值小波分解的图象拼合

图象拼合是一种基于图象的场景编码方法，它被很多基于图象的绘制IBR（image based rendering）系统采用，用来建立复杂的虚拟场景表示（例如，360°球面和柱面全景图、环境映照及高分辨率图象等）.基于复值小波多分辨率分解(Complex Wavelet Multiresolution Decomposition)提出了一种有效的图象拼合方法，它能同时地、逐步求精地对图象进行匹配和整合.首先，采用复值小波变换不仅可以保证全局优化的结果，还能够满足图象整合的规模不变和平移不变性.其次，基于多分辨     

Manifold Modeling and Its Application to Tubular Scene Manifold Mosaicing Algorithm

Manifold mosaicing is arguably the most important class of image mosaicing methods. The existing manifold mosaicing methods work reasonably well only for scenes with simple plane structure and for images taken in a usual way such that the camera??s motion direction is perpendicular to its optical axis. A novel manifold modeling theoretical framework is presented to unify the current image mosaicing methods. Based on this framework, an effective mosaicing algorithm is also proposed to mosaic tubular scenes which have failed most existing methods. We adopt a two-step shaping strategy to parallelize the optical flows and change the topological genus of the image strips by M?bius mappings and circular ring extending. We performed computational experiments via image sequences acquired from tubular scenes and obtained excellent panoramas. The theoretical framework and algorithms in this paper have immediate applications to many practical tubular scene mosaicing problems in medical imaging, industrial inspection, gaming, virtual reality and robotics.     

Drift-Free Real-Time Sequential Mosaicing

We present a sequential mosaicing algorithm for a calibrated rotating camera which can for the first time build drift-free, consistent spherical mosaics in real-time, automatically and seamlessly even when previously viewed parts of the scene are re-visited. Our mosaic is composed of elastic triangular tiles attached to a backbone map of feature directions over the unit sphere built using a sequential EKF SLAM (Extend Kalman Filter Simultaneous Localization And Mapping) approach. This method represents a significant advance on previous mosaicing techniques which either require off-line optimization or which work in real-time but use local alignment of nearby images and ultimately drift. We demonstrate the system’s real-time performance with real-time mosaicing results from sequences with 360 degrees pan. The system shows good global mosaicing ability despite the challenging conditions: hand-held simple low-resolution webcam, varying natural outdoor illumination, and people moving in the scene.     

基于比值法和模板匹配法的灰度图像拼接

提出一种改进的基于比值法和模板匹配法的灰度图像拼接算法。对两幅具有重叠区域的灰度图像，先通过设置拼接参数对话框，在另一幅图像中找到最佳匹配点，最后利用平滑因子对两幅图像的重叠区域进行数据融合操作，实现了灰度图像的快速自动拼接。实验证明．该方法对大部分灰度图像具有很好的拼接效果。     

Convolutional Sparse Coding for Capturing High‐Speed Video Content

Video capture is limited by the trade‐off between spatial and temporal resolution: when capturing videos of high temporal resolution, the spatial resolution decreases due to bandwidth limitations in the capture system. Achieving both high spatial and temporal resolution is only possible with highly specialized and very expensive hardware, and even then the same basic trade‐off remains. The recent introduction of compressive sensing and sparse reconstruction techniques allows for the capture of single‐shot high‐speed video, by coding the temporal information in a single frame, and then reconstructing the full video sequence from this single‐coded image and a trained dictionary of image patches. In this paper, we first analyse this approach, and find insights that help improve the quality of the reconstructed videos. We then introduce a novel technique, based on convolutional sparse coding (CSC), and show how it outperforms the state‐of‐the‐art, patch‐based approach in terms of flexibility and efficiency, due to the convolutional nature of its filter banks. The key idea for CSC high‐speed video acquisition is extending the basic formulation by imposing an additional constraint in the temporal dimension, which enforces sparsity of the first‐order derivatives over time.     

一种基于元胞自动机的图像拼接方法

描述了一种基于元胞自动机的图像拼接方法,采用元胞自动机提取图像特征点,然后以特征点邻域灰度互相关法进行特征点匹配,最后根据匹配的特征点对得到图像间的变换参数。实验结果表明,本方法不仅准确实现了图像拼接,而且降低了图像重叠度的要求。