Robust appearance-guided particle filter for object tracking with occlusion analysis

A major challenge for most tracking algorithms is how to address the changes of object appearance during tracking, incurred by large illumination, scale, pose variations and occlusions. Without any adaptability to these variations, the tracker may fail. In contrast, if adapts too fast, the appearance model is likely to absorb some improper part of the background or occluding objects. In this paper, we explore a tracking algorithm based on the robust appearance model which can account for slow or rapid changes of object appearance. Specifically, each pixel in appearance model is represented using mixture Gaussian models whose parameters are on-line learned by sequential kernel density approximation. The appearance model is then embedded into particle filter framework. In addition, an occlusion handling scheme is invoked to explicitly indicate outlier pixels and deal with occlusion events, thus avoiding the appearance model to be contaminated by undesirable outlier ‘thing’. Extensive experiments demonstrate that our appearance-based tracking algorithm can successfully track the object in the presence of dramatic appearance changes, cluttered background and even severe occlusions.     

一种改进粒子滤波目标跟踪算法

使用粒子滤波进行目标跟踪时,是用状态转移概率作为重要性函数,由于没有利用最新的观测信息,使得滤波效果不够理想.针对粒子滤波算法的这一缺陷, 提出了一种改进粒子滤波算法,该算法利用平方根无迹变换获得重要性函数,解决了粒子滤波算法以状态转移概率作为重要性函数的不足,同时保证了滤波过程中的稳定性.理论分析与仿真实例结果均表明,该算法提高了滤波的稳定性和精确性.     

Efficient object tracking by incremental self-tuning particle filtering on the affine group

We propose an incremental self-tuning particle filtering (ISPF) framework for visual tracking on the affine group, which can find the optimal state in a chainlike way with a very small number of particles. Unlike traditional particle filtering, which only relies on random sampling for state optimization, ISPF incrementally draws particles and utilizes an online-learned pose estimator (PE) to iteratively tune them to their neighboring best states according to some feedback appearance-similarity scores. Sampling is terminated if the maximum similarity of all tuned particles satisfies a target-patch similarity distribution modeled online or if the permitted maximum number of particles is reached. With the help of the learned PE and some appearance-similarity feedback scores, particles in ISPF become "smart" and can automatically move toward the correct directions; thus, sparse sampling is possible. The optimal state can be efficiently found in a step-by-step way in which some particles serve as bridge nodes to help others to reach the optimal state. In addition to the single-target scenario, the "smart" particle idea is also extended into a multitarget tracking problem. Experimental results demonstrate that our ISPF can achieve great robustness and very high accuracy with only a very small number of particles.     

基于粒子滤波的运动物体检测跟踪

提出了一种状态空间模型粒子滤波算法,并应用于运动目标的跟踪。该方法基于贝叶斯估计,利用粒子集来表示概率,通过递推的贝叶斯滤波来近似逼近最优化结果,在预设搜索区域用粒子群找到和目标模板最相似的中心位置,并以该位置作为观测值,进行跟踪。仿真实验结果和两种实际条件下效果比较表明该算法在跟踪低常速运动中精准性高,是一种有效的目标跟踪方法。     

基于粒子滤波的RFID室内节点定位跟踪研究

为了解决复杂室内环境下的RFID动态节点定位跟踪问题,文中建立了动态节点的运动模型和信号测量模型。仿真采用基于信号RSSI定位方法,结合运用等边三角形定位算法。由于室内射频信号具有较高的噪声污染,因此首先对采集的信号运用粒子滤波技术进行滤波处理,然后运用高斯粒子滤波算法对室内移动的RFID进行了定位跟踪预测。仿真结果表明该算法可以有效地对室内动态节点进行定位跟踪,精度较高,稳定性好,结果进一步说明高斯粒子滤波能有效地抑制室内射频噪声。     

基于多特征信息融合粒子滤波的红外目标跟踪

多特征信息有较好的检测性能和适应性,而粒子滤波则是一种处理目标跟踪模型的非线性和非高斯特点的有效方法,将两者优点结合并针对红外图像特点,提出一种基于多特征信息融合的跟踪算法,该方法按一定的权值系数利用目标颜色和纹理特征构建模型,并融合于粒子滤波框架中。实验表明该跟踪方法能准确地跟踪海上红外运动目标。     

Visual tracking and recognition using appearance-adaptive models in particle filters

We present an approach that incorporates appearance-adaptive models in a particle filter to realize robust visual tracking and recognition algorithms. Tracking needs modeling interframe motion and appearance changes, whereas recognition needs modeling appearance changes between frames and gallery images. In conventional tracking algorithms, the appearance model is either fixed or rapidly changing, and the motion model is simply a random walk with fixed noise variance. Also, the number of particles is typically fixed. All these factors make the visual tracker unstable. To stabilize the tracker, we propose the following modifications: an observation model arising from an adaptive appearance model, an adaptive velocity motion model with adaptive noise variance, and an adaptive number of particles. The adaptive-velocity model is derived using a first-order linear predictor based on the appearance difference between the incoming observation and the previous particle configuration. Occlusion analysis is implemented using robust statistics. Experimental results on tracking visual objects in long outdoor and indoor video sequences demonstrate the effectiveness and robustness of our tracking algorithm. We then perform simultaneous tracking and recognition by embedding them in a particle filter. For recognition purposes, we model the appearance changes between frames and gallery images by constructing the intra- and extrapersonal spaces. Accurate recognition is achieved when confronted by pose and view variations.     

结合幅度信息的粒子滤波机动目标被动跟踪

为提高杂波条件下的机动目标被动跟踪的性能,提出了一种新的粒子滤波目标被动跟踪算法。在声纳的输出端,提取信号的幅度信息(AI),建立多模型对转弯机动目标进行状态估计,以粒子滤波算法作为基本跟踪滤波算法,将AI与概率数据关联(PDA)算法中的似然比相结合,详细推导了结合AI的粒子滤波目标被动跟踪算法(PF-AI)实现的具体过程。在同一被动目标跟踪场景,同时使用单纯PDA算法、结合辅助信息的PDA算法和PF-AI进行被动跟踪仿真,分析了轨迹跟踪性能,并使用均方根误差比较了误差性能。仿真结果表明,与两种基于PDA的跟踪算法相比,PF-AI具有更高的跟踪精度,且算法易于实现。     

粒子滤波的卫星电子信息舰船目标跟踪算法

针对电磁探测卫星的重访时间间隔长、且捕获得到目标信息的时间为随机,目标运动模型难于精确建立,数据杂波干扰强等问题,结合卫星电子信息给出的辐射源电磁特征,基于粒子滤波提出了一种稳健的海上舰船目标跟踪算法。首先,采用二阶自回归的状态转移模型确定候选量测的关联区域,从而减少杂波的干扰;然后选取与目标电磁特征相似的量测进行粒子滤波的状态更新,并通过重采样操作剔除权值较小的粒子以提高跟踪算法的精确性与稳健性。仿真与真实数据的实验结果表明,该方法在强杂波干扰下可以稳定跟踪卫星电子信息中的海上舰船目标并且具有较高的精确性与稳健性。      

基于粒子滤波和稀疏表示的视频目标跟踪

文中将视频目标跟踪看成在粒子滤波框架下的稀疏表示问题,提出了具鲁棒性的视觉跟踪方法。在跟踪过程中,将目标的先验知识和目标状态及其观测结果联系起来构造贝叶斯概率模型,根据基本粒子滤波算法对目标位置进行估计。候选目标通过目标模板和琐碎模板稀疏表示,用l1范数稀疏正则化算法求解稀疏问题,选取具有最小残差的候选目标为跟踪结果。通过动态更新模板和非负性约束两种策略,使算法在目标遮挡、噪声、形变等各种干扰因素下,均达到了很好的跟踪性能。     

结合粒子滤波的判别尺度空间目标跟踪算法

为了解决目前跟踪算法在运动目标被遮挡和尺度变换时跟踪效果不佳的问题,提出了一种结合粒子滤波的判别尺度空间跟踪算法.提取相邻两帧的目标区域,计算目标区域的结构相似性并与更新阈值进行比较,从而判断目标是否发生遮挡;其次,若发生遮挡,启用基于颜色分布的粒子滤波算法跟踪目标,反之,用判别尺度空间跟踪算法(DSST)中的位置滤波...     

Energy-efficient collaborative target tracking algorithm using cost-reference particle filtering in wireless acoustic sensor networks

Target tracking is one of the most important applications of wireless sensor networks. Optimized computation and energy dissipation are critical requirements to save the limited resource of sensor nodes. A new robust and energy-efficient collaborative target tracking framework is proposed in this article. After a target is detected, only one active cluster is responsible for the tracking task at each time step. The tracking algorithm is distributed by passing the sensing and computation operations from one cluster to another. An event-driven cluster reforming scheme is also proposed for balancing energy consumption among nodes. Observations from three cluster members are chosen and a new class of particle filter termed cost-reference particle filter (CRPF) is introduced to estimate the target motion at the cluster head. This CRPF method is quite robust for wireless sensor network tracking applications because it drops the strong assumptions of knowing the probability distributions of the system process and observation noises. In simulation experiments, the performance of the proposed collaborative target tracking algorithm is evaluated by the metrics of tracking precision and network energy consumption.     

应用于运动视频目标跟踪的改进粒子滤波模型技术研究

粒子滤波作为目标跟踪的主流技术,在人体运动视频分析中具有广阔的应用前景。为了进一步提高目标追踪的精度,提出一种基于改进粒子滤波模型的运动视频目标跟踪算法。采用HSV分布模型构建目标观测模型,结合粒子滤波器和退化权值检测运动目标是否出现在目标观测模型中。最后引入遗传算法对粒子滤波算法进行改进,以便消除粒子退化的现象。在体育运动员视频中进行测试验证,实验结果表明,提出的算法能够有效完成运动视频中的人体目标跟踪,与其他算法相比,提出算法的精度和运行效率更高。     

特征融合的灰狼优化粒子滤波目标跟踪算法

针对传统粒子滤波算法在跟踪目标所处环境迁移,目标姿态变化和发生遮挡时容易出现跟踪框漂移现象,提出一种基于灰狼算法优化的粒子滤波跟踪方法(GWOPF)。首先,将全局特征HSV颜色特征和局部特征方向梯度直方图(HOG)特征加权融合建立观测模型;然后,用灰狼算法(GWO)优化粒子滤波算法结构,利用GWO位置更新机制改善粒子空间分布状况,在粒子重采样前进行权值自适应调节,解决原始粒子滤波方法采样时出现的粒子退化问题并优化滤波效果。实验结果表明,改进后的算法在具有挑战的Tiger和Girl视频序列中跟踪成功率分别达到了97.5%和95.0%,单帧处理时间缩短至24.6 ms和18.4 ms,具有较高的跟踪精度和良好的鲁棒性,能够应对跟踪目标发生旋转、部分遮挡等情况以及实时性要求。     

基于粒子滤波框架联合仿射和外貌模型的目标跟踪

针对视频序列中目标的跟踪问题,提出了一种基于粒子滤波框架的联合仿射和外貌模型的目标跟踪算法.该算法首先提取图像帧之间的相关特征点,通过求解Sylvester方程得到仿射参数,然后将仿射参数嵌入到基于仿射群的粒子滤波框架中进行平滑估计.利用基于仿射群的一阶自回归过程模拟状态的变化,联合仿射特征点模型和外貌模型进行似然估计,得到粒子的最佳平均状态,进而对目标实施跟踪.实验结果表明,在目标经历姿势和尺度变化、遮挡以及复杂背景等情况下,提出的算法能够有效地跟踪目标,较之其他相关算法具有很强的鲁棒性.     

TDOA positioning in NLOS scenarios by particle filtering

A method is proposed for position estimation from non line of sight time difference of arrivals (TDOA) measurements. A general measurement model for TDOA accounting for non line of sight conditions is developed; then, several simplifying working assumptions regarding this model are discussed to allow the efficient implementation of a particle filter localization algorithm. This algorithm is tested and compared with an extended Kalman filter procedure, both in simulation, generating artificial measures, and with real data.     

Gaussian particle filtering

Sequential Bayesian estimation for nonlinear dynamic state-space models involves recursive estimation of filtering and predictive distributions of unobserved time varying signals based on noisy observations. This paper introduces a new filter called the Gaussian particle filter. It is based on the particle filtering concept, and it approximates the posterior distributions by single Gaussians, similar to Gaussian filters like the extended Kalman filter and its variants. It is shown that under the Gaussianity assumption, the Gaussian particle filter is asymptotically optimal in the number of particles and, hence, has much-improved performance and versatility over other Gaussian filters, especially when nontrivial nonlinearities are present. Simulation results are presented to demonstrate the versatility and improved performance of the Gaussian particle filter over conventional Gaussian filters and the lower complexity than known particle filters.     

Stochastic optimisation for high-dimensional tracking in dense range maps

The main challenge of tracking articulated structures like hands is their many degrees of freedom (DOFs). A realistic 3-D model of the human hand has at least 26 DOFs. The arsenal of tracking approaches that can track such structures fast and reliably is still very small. This paper proposes a tracker based on stochastic meta-descent (SMD) for optimisations in such high-dimensional state spaces. This new algorithm is based on a gradient descent approach with adaptive and parameter-specific step sizes. The SMD tracker facilitates the integration of constraints, and combined with a stochastic sampling technique, can get out of spurious local minima. Furthermore, the integration of a deformable hand model based on linear blend skinning and anthropometrical measurements reinforces the robustness of the tracker. Experiments show the efficiency of the SMD algorithm in comparison with common optimisation methods.     

Cloud tracking by scale space classification

The problem of cloud tracking within a sequence of geo-stationary satellite images has direct relevance to the analysis of cloud life cycles and to the detection of cloud motion vectors (CMVs). The proposed approach first identifies a homogeneous consistent cloud mass for tracking and then establishes motion correspondence within an image sequence. In contrast to the crosscorrelation based approach as adopted in automatic CMV detection analysis, a scale space classifier is designed to detect cloud mass in the source image taken at time t and the destination image at time t+δt. Boundaries of the extracted cloud segments are matched by computing a correspondence between high curvature points. This shape based method is capable of tracking in the cases of rotation, scaling, and shearing, while the correlation technique is limited to translational motion. The final tracking results provide motion magnitude and direction for each contour point, allowing reliable estimation of meteorological events and wind velocities aloft. With comparable computational expense, the scale space classification technique exceeds the performance of the traditional correlation-based approach in terms of reduced localization error and false matches     

Object tracking with particle filtering in fluorescence microscopy images: application to the motion of neurofilaments in axons

Neurofilaments are long flexible cytoplasmic protein polymers that are transported rapidly but intermittently along the axonal processes of nerve cells. Current methods for studying this movement involve manual tracking of fluorescently tagged neurofilament polymers in videos acquired by time-lapse fluorescence microscopy. Here, we describe an automated tracking method that uses particle filtering to implement a recursive Bayesian estimation of the filament location in successive frames of video sequences. To increase the efficiency of this approach, we take advantage of the fact that neurofilament movement is confined within the boundaries of the axon. We use piecewise cubic spline interpolation to model the path of the axon and then we use this model to limit both the orientation and location of the neurofilament in the particle tracking algorithm. Based on these two spatial constraints, we develop a prior dynamic state model that generates significantly fewer particles than generic particle filtering, and we select an adequate observation model to produce a robust tracking method. We demonstrate the efficacy and efficiency of our method by performing tracking experiments on real time-lapse image sequences of neurofilament movement, and we show that the method performs well compared to manual tracking by an experienced user. This spatially constrained particle filtering approach should also be applicable to the movement of other axonally transported cargoes.