基于子块运动估计补偿的视频误码块掩饰

视频数据在传输过程中存在着信道误码或丢包等现象,为了达到提高视频误码掩饰的目的,可利用子块运动估计方法,预测出在时间方向上的相关信息,通过运动补偿进行误码掩饰,同时为了消除子块补偿的边缘效应,进一步利用重叠块运动补偿方法以提高掩饰效果。     

一种基于预测的改进的三步搜索算法

基于对运动矢量分布的中心偏向特性研究,结合零运动预判断,提出了一个基于预测的改进的三步搜索算法(PBITSS),有效地提高了运动估计搜索速度并保持较高的搜索精度.实验结果显示,与三步搜索算法(TSS)相比,图像质量和搜索速度都得到了提高,综合性能高于TSS算法.     

Fast and accurate global motion compensation

Video understanding has attracted significant research attention in recent years, motivated by interest in video surveillance, rich media retrieval and vision-based gesture interfaces. Typical methods focus on analyzing both the appearance and motion of objects in video. However, the apparent motion induced by a moving camera can dominate the observed motion, requiring sophisticated methods for compensating for camera motion without a priori knowledge of scene characteristics. This paper introduces two new methods for global motion compensation that are both significantly faster and more accurate than state of the art approaches. The first employs RANSAC to robustly estimate global scene motion even when the scene contains significant object motion. Unlike typical RANSAC-based motion estimation work, we apply RANSAC not to the motion of tracked features but rather to a number of segments of image projections. The key insight of the second method involves reliably classifying salient points into foreground and background, based upon the entropy of a motion inconsistency measure. Extensive experiments on established datasets demonstrate that the second approach is able to remove camera-based observed motion almost completely while still preserving foreground motion.     

视频图像序列运动参数估计与动态拼接

本文采用多重分层叠代算法来估计全局运动参数,并提出应用于动态拼接的运动分割新方法,实现既有摄像机运动又有物体运动的视频图像序列自动拼接。我们的方法基本步骤如下：首先进行全局运动参数的初始估计,并且在分层叠代过程中进行区域分类,得到初始运动模板。接着空间分割原始图像,先根据图像的空间属性由底向上分层合并图像空间区域,再利用视频图像时间属性进一步向上合并,得到图像空间分割结果。然后结合初始运动模板和图像空间分割结果,采用区域分类新方法重新对图像空间分割结果的每个区域进行分类。然后根据分类结果逐步精确求解全局运动参数。最后进行图像合成,得到全景拼接图像。我们的方法利用了多重分层叠代的优点,并且充分考虑到视频图像空间和时间上的属性,实现了运动物体和覆盖背景的精确分割,避免了遮挡问题对全局运动参数估计精度的影响。而且在图像合成时我们解决了拼接图可能产生模糊或某些区域不连续等问题。实验结果表明我们的方法实现了动态视频图像序列高质量的全景拼接。     

基于SIFT特征匹配的视频稳像算法研究

为了解决运动情况下的视频图像去抖问题,本文提出了一种新型的去抖算法。首先利用SIFT算法提取出特征点,并利用RANSAC算法进行优化处理,进行图像的全局运动估计和全局运运补偿,实现视频图像的去抖功能。本文实现了以该方法为基本算法的原型系统,能够有效地增加视频图像的平滑度。     

基于全变分的运动分割模型及分裂 Bregman 算法

提出了一种基于全变分的运动分割模型,可以适用于2D/3D视频.首先, 通过活动轮廓模型将分割与估计融合在同一能量函数中, 该模型能够同时进行分割曲面的演化和运动参数的估计. 其次,通过凸松弛方法将原始问题转化为等价的全变分模型, 克服了局部最小值问题.最后,采用分裂Bregman快速算法进行求解. 多组实验证明了本文方法对2D/3D视频的通用性和算法的高效性.     

利用视觉特征进行Motion JPEG2000低频子带重构

提出了一种针对Motion JPEG2000低频子带完全受损情况下的错误掩盖算法,该算法对高频图像应用Sobel算子进行图像锐化;随后利用视频序列的时间域相关性,运动估计判断参考帧与受损帧之间物体运动剧烈程度,利用参考帧的低频信息,对受损帧依据其运动剧烈程度分别进行运动补偿处理或低频子带代替处理.该算法计算量小,适合实时应用,且充分考虑视觉特点,对部分运动估计结果进行变换尺度后的验证,实验结果表明其恢复的图像符合人眼主观感受.     

A framework for heading-guided recognition of human activity

A combined 2D, 3D approach is presented that allows for robust tracking of moving people and recognition of actions. It is assumed that the system observes multiple moving objects via a single, uncalibrated video camera. Low-level features are often insufficient for detection, segmentation, and tracking of non-rigid moving objects. Therefore, an improved mechanism is proposed that integrates low-level (image processing), mid-level (recursive 3D trajectory estimation), and high-level (action recognition) processes. A novel extended Kalman filter formulation is used in estimating the relative 3D motion trajectories up to a scale factor. The recursive estimation process provides a prediction and error measure that is exploited in higher-level stages of action recognition. Conversely, higher-level mechanisms provide feedback that allows the system to reliably segment and maintain the tracking of moving objects before, during, and after occlusion. Heading-guided recognition (HGR) is proposed as an efficient method for adaptive classification of activity. The HGR approach is demonstrated using “motion history images” that are then recognized via a mixture-of-Gaussians classifier. The system is tested in recognizing various dynamic human outdoor activities: running, walking, roller blading, and cycling. In addition, experiments with real and synthetic data sets are used to evaluate stability of the trajectory estimator with respect to noise.     

基于运动场无序度的快速块模式选择算法

针对H．264的多模式运动估计,引入运动无序度的概念来刻画当前宏块的运动混乱程度,通过理论和实验统计分析,建立了无序度和最优块模式之间的关联模型．基于该模型,提出了一种基于当前宏块运动场无序度的块模式判定算法(Fast Mode Selection algorithm based on Chaos Degree of Motion Field,CDMF—FMS),最后的实验结果表明,该算法在基本保持原来参考软件编码性能的基础上,整体编码时间平均减少20％以上．     

基于可变形运动模型的多角色语义化运动合成

对于一个完整的虚拟环境而言,智能的人群运动会使其更为生动、逼真。针对人群运动数据存在维度高、可控性差的问题,提出一种多角色可变形运动模型,其将人体运动分解为几何与时间变化两部分,并使用PCA算法进行有效降维,构建可变形运动模型的低维语义空间。实验结果表明,提出的方法能根据语义需求调节语义参数,实现多角色的语义化运动分析与合成。     

基于相对形变模型及正则化技术的人体运动估计

为了使根据人体行走的单目动态图象序列,对人体手臂及腿部的运动及结构参数进行估计的结果更为可信、更具鲁棒性,提出了一种基于相对形变模型及正则化技术的人体运动估计方法,该方法首先在物体中心坐标的运动表示方式下,通过在刚体运动模型中加入形变系数的方法给出了基于相对形变概念的非刚体运动模型;然后,根据这一非刚体运动模型进行正则化运动及结构参数的估计,再以正则化的形式融入人体运动的先验知识,使运动估计的结果更具鲁棒性,实验结果证明,该方法有效地反映了人体的非刚体运动模式,运动模型中所加入的相对形变系数也一定程度反映了人体的运动规律。     

基于全局运动特征的摄像机运动定性分析系统

本文介绍了一种实时的利用全局运动信息检测摄像机运动的系统。该系统通过对视频数据相邻帧之间的运动关系的分析,来检测摄像机是否按照控制命令产生了相应动作序列。实验结果表明,在实际的视频监控应用中,该检测方案能够在满足实时性要求的前提下,给出高准确率的检测效果。     

A generic structure-from-motion framework

We introduce a generic structure-from-motion approach based on a previously introduced, highly general imaging model, where cameras are modeled as possibly unconstrained sets of projection rays. This allows to describe most existing camera types including pinhole cameras, sensors with radial or more general distortions, catadioptric cameras (central or non-central), etc. We introduce a structure-from-motion approach for this general imaging model, that allows to reconstruct scenes from calibrated images, possibly taken by cameras of different types (cross-camera scenarios). Structure-from-motion is naturally handled via camera independent ray intersection problems, solved via linear or simple polynomial equations. We also propose two approaches for obtaining optimal solutions using bundle adjustment, where camera motion, calibration and 3D point coordinates are refined simultaneously. The proposed methods are evaluated via experiments on two cross-camera scenarios—a pinhole used together with an omni-directional camera and a stereo system used with an omni-directional camera.     

自适应的动态搜索范围运动估计算法

为更加有效地提高运动估计速度,提出一种自适应动态搜索范围运动估计算法,从后续快速运动估计算法的运动矢量预测集中自适应地选择与当前编码块相关性最强的运动矢量预测值作为搜索范围的中心点,根据预测集中运动矢量预测值的大小、方向自适应地决定水平、垂直及正负方向的非对称搜索范围。将该算法融合到UMHexagonS和FFS算法中进行广泛的实验测试,结果表明其能在基本保持重建图像质量的同时,至少分别减少运动估计运算量的22.13%和76.57%。     

Human motions representation and recognition by directional motion history images

In this paper, we describe a technique for representing and recognizing human motions using directional motion history images. A motion history image is a single human motion image produced by superposing binarized successive motion image frames so that older frames may have smaller weights. It has, however, difficulty that the latest motion overwrites older motions, resulting in inexact motion representation and therefore incorrect recognition. To overcome this difficulty, we propose directional motion history images which describe a motion with respect to four directions of movement, i.e. up, down, right and left, employing optical flow. The directional motion history images are thus a set of four motion history images defined on four optical flow images. Experimental results show that the proposed technique achieves better performance in the recognition of human motions than the existent motion history images. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

An interactive data-driven driving simulator using motion blending

Compared to the motion equations the data-driven method can simulate reality from sampling of real motions but real-time interaction between a user and the simulator is problematic. Existing data-driven motion generation methods simply record and replay the motion of the vehicle. Character animation technology enables a user to control motions that are generated by a motion capture database and an appropriate motion control algorithm. We propose a data-driven motion generation method and implement a driving simulator by adapting the method of motion capture. The motion data sampled from a real vehicle are transformed into appropriate data structures called motion blocks, and then a series of motion blocks are saved into the motion database. During simulation, the driving simulator searches for and synthesizes optimal motion blocks from the motion database and generates motion streams that reflect the current simulation conditions and parameterized user demands. We demonstrate the proposed method through experiments with the driving simulator.     

一种新区间值vague集及其在模式识别中的应用

基于现有定义证明了区间值vague集并非vague集的扩展,并提出了一种新的区间值vague集定义。证明了vague集和区间值vague集都是新区间值vague集的特例。进而提出了带参数区间值vague集的概念,并从已知隶属度和非隶属度出发,重点分析了带参数区间值vague集的构造。将模式识别与医疗诊断案例进行了对比。仿真实验结果表明,带参数区间值的vague集方法比传统的vague集方法更全面且更具灵活性。     

一种面向快速全局运动估计的渐进精细闭值方法

快速全局运动估计的关键在于全局运动区域与局部运动区域的分割,其难点在于阂值的设定。提出一种面向快速全局运动的渐进精细阂值方法,该方法分为两步:第一步,用一个将统计特性与均值阂值相结合的亮度残差阂值模型来大致划分局部运动区域与全局运动区域,从而得到全局运动佑计区域的近似集合;第二步,使用一种运动矢量残差分级阂值技术在能量残差函数最小化迭代过程中逐步细化全局运动像素点集合,最后分离出完整的全局运动区域,从而实现快速的运动估计。     

Computing depth maps from descent images

In the exploration of the planets of our solar system, images taken during a landers descent to the surface of a planet provide a critical link between orbital images and surface images. The descent images not only allow us to locate the landing site in a global coordinate frame, but they also provide progressively higher-resolution maps for mission planning. This paper addresses the generation of depth maps from the descent images. Our approach has two steps, motion refinement and depth recovery. During motion refinement, we use an initial motion estimate in order to avoid the intrinsic motion ambiguity. The objective of the motion-refinement step is to adjust the motion parameters such that the reprojection error is minimized. The depth-recovery step correlates adjacent frames to match pixels for triangulation. Due to the descending motion, the conventional rectification process is replaced by a set of anti-aliasing image warpings corresponding to a set of virtual parallel planes. We demonstrate experimental results on synthetic and real descent images.Received: 7 November 2002, Accepted: 13 September 2004, Published online: 25 February 2005 Correspondence to: Clark F. Olson     

基于运动矢量空间相关性的H.264分像素运动估计

随着整像素运动估计快速算法的发展,分像素运动估计的计算量在运动估计中所占比重越发明显。为了减少分像素运动估计的计算量,提出了一种利用运动矢量空间相关性来预测整像素运动块,对整像素运动块进行分像素搜索过程跳过的分像素运动估计方法。实验结果表明,该算法与全分像素搜索算法结合使用,在基本保持搜索精度不变的情况下,比单纯的全分像素搜索算法减少60%左右的分像素搜索点。该算法可与其他快速分像素搜索算法结合使用,以获得更好的编码性能。