基于自适应Kalman预测器的运动估计算法

利用图像序列估计目标运动速度是机器人视觉中的一项重要研究内容。它应用在机器人操作、导航、视觉跟踪等多项领域中。这些应用一般均要求运动估计算法具有较好的实时性和抗噪能力。卡尔曼滤波器和预测器正符合上述要求。该文基于运动图像的仿射模型，探讨从序列图像中预测目标三维平动速度的卡尔曼预测算法。首先建立运动目标的“当前”统计模型，然后根据运动图像的仿射模型找出图像运动参数与目标三维速度间的关系(图像运动参数由目标图像的几何矩计算获得)。最后结合自适应卡尔曼滤波和卡尔曼一步预测算法设计自适应卡尔曼一步预测器。为减轻预测器的发散性，对初始状态进行估计。仿真结果表明，基于“当前”统计模型和运动图像仿射模型设计出的自适应卡尔曼一步预测器具有较高的精度。     

基于线阵CCD的目标跟踪

图像序列运动目标跟踪是计算机视觉领域的核心课题之一.本文采用线阵CCD相机获取图像序列.并提出了一种改进的相关跟踪算法时运动目标进行匹配和跟踪的算法,实现了目标的快速匹配与实时跟踪的目的.     

无人机多机动目标自主探测与跟踪

无人机机载相机图像中机动目标尺寸较小而且会发生显著变化,加上大量的背景噪声干扰,给目标探测和跟踪带来很大困难.针对这些问题,本文提出了一种在无人机机载相机图像序列中自主探测与跟踪多个机动目标的方法.首先,提取目标的图像数字特征并采用级联分类算法进行特征分类,得到目标的强分类器,对目标进行自主探测搜索.然后,基于全局最优关联算法对探测回波进行关联滤波,实现对多个机动目标的跟踪与识别,其中最优关联代价矩阵融合了距离和方向信息,提高了关联和跟踪的鲁棒性.将无人机航拍图像序列中的地面坦克作为目标进行实验,结果表明本文算法可以实现对多个机动目标的自主探测和跟踪,并具有较好的跟踪鲁棒性.     

一种移动机器人对运动目标的检测跟踪方法

从序列图像中有效地自动提取运动目标区域和跟踪运动目标是自主机器人运动控制的研究热点之一.给出了连续图像帧差分和二次帧差分改进的图像HIS差分模型,采用自适应运动目标区域检测、自适应阴影部分分割和噪声消除算法,对无背景图像条件下自动提取运动目标区域.定义了一些运动目标的特征分析和计算,通过特征匹配识别所需跟踪目标的区域.采用Kalman预报器对运动目标状态的一步预测估计和两步增量式跟踪算法,能快速平滑地实现移动机器人对运动目标的跟踪驱动控制.实验结果表明该方法有效.     

基于几何活动轮廓模型的目标跟踪与快速运动估计

为了快速灵活地实现对图像序列中的目标运动的跟踪与描述,首先基于几何活动轮廓模型,提出了一种目标跟踪与运动估计的耦合变分模型,该模型可在进行多个目标跟踪的同时,估计运动矢量场,并以此修正跟踪的结果;然后分别从耦合模型的两个方面,讨论了模型对序列图像处理的执行效率和精度,接着针对耦合框架中的目标跟踪环节,改进了几何活动轮廓模型的外力场,从而增强了模型的跟踪能力和收敛速度;最后针对运动估计问题,由于耦合框架基于几何活动轮廓模型,因此框架在跟踪过程中,天然地提供了图像水平集信息,并在此信息的基础上,提出了一套用于快速计算图像序列局部目标的运动矢量场的方法,其对混合有非刚性运动的目标也能有较好的逼近结果。多种类型图像的数值实验结果证明,整套框架是有效的和鲁棒的,而且与经典光流方法进行的对比实验表明,新算法可以快速准确地同时估计图像序列中局部运动目标的轮廓位置与运动参数,从而为后续图像分析与处理打下了良好的基础。     

序列图像中的目标区域跟踪算法的设计

在测量高炮在基于雷达信号对飞行目标的自动跟踪精度时,采用的是在火炮身管上安装摄像机,然后对所摄取的图像进行处理并最终测算出跟踪精度.此种情况下,摄像机和目标均处于运动状态,对所获得的序列图像,分析了其特点,首先对图像进行滤波降噪,然后对图像进行了分割并使用数学形态学算法修正了分割结果的形态,基于图像中区域的特征,最后设计了一个自动跟踪图像序列中目标区域的算法,给出了判断是否发生误跟踪的标准,并对跟踪错误的情况进行了处理.根据对实际图像序列中目标区域的跟踪结果验证,本算法是可行的.     

压缩感知跟踪中的特征选择与目标模型更新

目的 为了增强压缩感知跟踪算法在复杂场景下的性能,本文提出了一种特征选择与目标模型更新的改进跟踪方法。方法 提出的方法包含两方面的改进,一是根据特征的正负类条件概率分布的距离选择能有效区分目标与背景的特征;二是根据当前目标与原始目标的差异自适应更新目标外观模型,使得目标遇到较大遮挡或者姿态频繁改变时目标外观模型不会被错误更新。结果 实验表明,对于十个复杂环境下的经典视频序列,本文提出的基于压缩感知的改进跟踪算法在中心误差、成功率和精确度三个指标上均优于最近三个代表性的跟踪算法。结论 提出的新的特征选择和目标模型更新方法,既增强了压缩感知跟踪算法的鲁棒性,又加快了跟踪速度。     

一种基于仿射变换模型的目标跟踪算法

在图像目标跟踪的应用中,传统方法多采用基于平移运动模型和相关（correlation）类型匹配准则的跟踪算法。该类算法以目标仅发生平移运动为假设前提,难以有效适应目标在图像中通常会发生的缩放、旋转和错切等变化。本文应用了一种基于仿射变换模型的目标跟踪算法。该算法建立起包含六个参数的仿射变换模型,以其描述目标在序列图像中的变化,然后构造适当的匹配误差目标函数,并采用牛顿迭代法求解得到最优的仿射参数。实验结果表明,该算法具有较强的鲁棒性,能够得到较好的跟踪效果。     

视频图像中的车辆检测跟踪和分类

介绍了一种在固定的单摄像头拍摄的交通图像序列中检测、跟踪、分类车辆的方法。该方法大致可分为三部分:抽取背景图像和图像分割;基于针孔模型的摄像机定标,计算透视投影矩阵;利用区域特征进行匹配跟踪,建立目标链,恢复目标三维信息,采用模型匹配法对车型分类。实验证明该方法简单可行。     

基于QP_TR信任域方法的低信噪比序列图像目标跟踪*

运动平台上低信噪比序列图像中的目标跟踪面临着两大困难:平台运动导致图像存在全局平移,使得目标在相邻帧间脱离跟踪算法搜索窗;图像中的干扰使得跟踪窗口经常跳动而导致跟踪失败.鉴于QP_TR信任域算法的优良性能,针对上述两个问题提出了一种新的基于QP_TR信任域和Kalman滤波的跟踪算法.该算法利用QP_TR进行图像稳定和模板匹配,通过Kalman滤波器状态估计滤除干扰.与三步搜索方法相比,加大了搜索窗大小的同时减少了模板匹配的次数,提高了性能.在真实图像序列上进行的实验表明,该算法能有效地稳定运动图像,实现运动平台上低信噪比序列图像中目标的稳定跟踪.     

融合SPA遮挡分割的多目标跟踪方法

复杂环境下的多目标视频跟踪是计算机视觉领域的一个难点,有效处理目标间遮挡是解决多目标跟踪问题的关键。将运动分割方法引入目标跟踪领域,提出一种融合骨架点指派(SPA)遮挡分割的多目标跟踪方法。由底层光流信息得到骨架点,并估计骨架点遮挡状态;综合使用目标外观、运动、颜色信息等高级语义信息,将骨架点指派给各个目标;最后以骨架点为核,对运动前景密集分类,得到准确的目标前景像素;在粒子滤波器跟踪框架下,使用概率外观模型进行多目标跟踪。在PETS2009数据集上的实验结果表明,文中方法能够改进现有多目标跟踪方法对目标间交互适应性较差的缺点,更好地处理动态遮挡问题。     

Segmenting and tracking multiple objects under occlusion using multi-label graph cut

This paper proposes a new method to segment and track multiple objects through occlusion by integrating spatial-color Gaussian mixture model (SCGMM) into an energy minimization framework. When occlusion does not occur, a SCGMM is learned for each object. When the objects are subject to occlusion, energy minimization is used to segment the objects from occlusion. To make the learned SCGMMs suitable for the segmentation of the current occlusion, a displacing procedure is utilized to adapt the SCGMMs to the spatial variations. A multi-label energy function is formulated building on the displaced SCGMMs and then minimized using the multi-label graph cut algorithm, thus leading to both the segmentation and tracking results of the objects with occlusion. Experimental validation of the proposed method is performed and presented on several video sequences.     

Tracking objects with generic calibrated sensors: An algorithm based on color and 3D shape features

We present a color and shape based 3D tracking system suited to a large class of vision sensors. The method is applicable, in principle, to any known calibrated projection model. The tracking architecture is based on particle filtering methods where each particle represents the 3D state of the object, rather than its state in the image, therefore overcoming the nonlinearity caused by the projection model. This allows the use of realistic 3D motion models and easy incorporation of self-motion measurements. All nonlinearities are concentrated in the observation model so that each particle projects a few tens of special points onto the image, on (and around) the 3D object’s surface. The likelihood of each state is then evaluated by comparing the color distributions inside and outside the object’s occluding contour. Since only pixel access operations are required, the method does not require the use of image processing routines like edge/feature extraction, color segmentation or 3D reconstruction, which can be sensitive to motion blur and optical distortions typical in applications of omnidirectional sensors to robotics. We show tracking applications considering different objects (balls, boxes), several projection models (catadioptric, dioptric, perspective) and several challenging scenarios (clutter, occlusion, illumination changes, motion and optical blur). We compare our methodology against a state-of-the-art alternative, both in realistic tracking sequences and with ground truth generated data.     

结合Camshift和Kalman预测的运动目标跟踪

针对单一的CamShift跟踪算法在目标发生遮挡时非常容易致使跟踪目标失败的问题,本文提出了一种基于CamShift和Kalman预测的跟踪算法。首先,采用帧间差分阈值法来快速、精确地检测和提取出运动目标;然后,通过在CamShift算法中使用运动目标的颜色特征,在图像序列中找到运动目标的所在位置和大小;最后,使用Kalman滤波预测目标的位置,进而有效地解决了背景中大面积相同颜色的干扰和目标部分被遮挡等问题。用无线遥控车完成了运动目标的跟踪实验,实验证明结合CamShift算法和Kalman预测滤波能实时、准确地跟踪目标。     

粒子滤波的视频目标跟踪算法研究

目标跟踪是计算机视觉和图像处理的一个重点课题,在视频监控、机器人视觉导航以及智能交通控制中具有广泛的应用前景.通过粒子滤波技术,研究了如何整合颜色特征、前景信息和积分图运算等技术实现视频目标跟踪的粒子滤波算法.在对目标进行分割中采用了混合高斯背景建模方法;同时结合积分直方图的计算方法对颜色特征进行分段统计及相互遮挡的判断,实现基于粒子滤波的目标跟踪算法的优化,解决跟踪中诸如遮挡、光照变化、背景干扰、尺寸变化等难以解决的问题.实验结果表明提出的方法达到了预期目标.     

A 2D/3D model-based object tracking framework

This paper presents a robust framework for tracking complex objects in video sequences. Multiple hypothesis tracking (MHT) algorithm reported in (IEEE Trans. Pattern Anal. Mach. Intell. 18(2) (1996)) is modified to accommodate a high level representations (2D edge map, 3D models) of objects for tracking. The framework exploits the advantages of MHT algorithm which is capable of resolving data association/uncertainty and integrates it with object matching techniques to provide a robust behavior while tracking complex objects. To track objects in 2D, a 4D feature is used to represent edge/line segments and are tracked using MHT. In many practical applications 3D models provide more information about the object's pose (i.e., rotation information in the transformation space) which cannot be recovered using 2D edge information. Hence, a 3D model-based object tracking algorithm is also presented. A probabilistic Hausdorff image matching algorithm is incorporated into the framework in order to determine the geometric transformation that best maps the model features onto their corresponding ones in the image plane. 3D model of the object is used to constrain the tracker to operate in a consistent manner. Experimental results on real and synthetic image sequences are presented to demonstrate the efficacy of the proposed framework.     

基于二阶非线性投票的多目标跟踪算法*

提出了基于二阶非线性投票的多目标跟踪算法。该算法通过目标匹配得到同一目标在不同帧中的位置,同时利用特征监测来处理目标的遮挡、分裂问题,并实现目标特征的实时更新。在目标匹配过程中,通过对目标前一帧与当前帧的特征相似性进行投票,得到匹配目标。利用视频图像进行实验,结果表明,该方法对噪声、阴影、遮挡、分裂等具有良好的鲁棒性,较好地实现了多目标的跟踪。     

3D head tracking under partial occlusion

A new algorithm for 3D head tracking under partial occlusion from 2D monocular image sequences is proposed. The extended superquadric (ESQ) is used to generate a geometric 3D face model in order to reduce the shape ambiguity during tracking. Optical flow is then regularized by this model to estimate the 3D rigid motion. To deal with occlusion, a new motion segmentation algorithm using motion residual error analysis is developed. The occluded areas are successfully detected and discarded as noise. Furthermore, accumulation error is heavily reduced by a new post-regularization process based on edge flow. This makes the algorithm more stable over long image sequences. The algorithm is applied to both synthetic occlusion sequence and real image sequences. Comparisons with the ground truth indicate that our method is effective and is not sensitive to occlusion during head tracking.     

自动选择跟踪窗尺度的Mean-Shift算法

实用的跟踪系统要求能实时地适应运动目标的外观变化,尺度固定不变的跟踪窗口不能有效地跟踪存在明显尺度变化的目标。本文将多尺度图像的信息量度量方法引入到运动目标跟踪中,提出了一种跟踪窗口自动更新算法,并用此算法改进了基于颜色直方图的Mean-Shift跟踪方案。实验结果表明,改进的跟踪算法对尺寸逐渐减小和逐渐增大的目标都能自动选择合适的跟踪窗口大小。     

Merging artificial objects with marker-less video sequences based on the interacting multiple model method

Inserting synthetic objects into video sequences has gained much interest in recent years. Fast and robust vision-based algorithms are necessary to make such an application possible. Traditional pose tracking schemes using recursive structure from motion techniques adopt one Kalman filter and thus only favor a certain type of camera motion. We propose a robust simultaneous pose tracking and structure recovery algorithm using the interacting multiple model (IMM) to improve performance. In particular, a set of three extended Kalman filters (EKFs), each describing a frequently occurring camera motion in real situations (general, pure translation, pure rotation), is applied within the IMM framework to track the pose of a scene. Another set of EKFs,one filter for each model point, is used to refine the positions of the model features in the 3-D space. The filters for pose tracking and structure refinement are executed in an interleaved manner. The results are used for inserting virtual objects into the original video footage. The performance of the algorithm is demonstrated with both synthetic and real data. Comparisons with different approaches have been performed and show that our method is more efficient and accurate.