Multicamera Tracking of Articulated Human Motion Using Shape and Motion Cues

We present a completely automatic algorithm for initializing and tracking the articulated motion of humans using image sequences obtained from multiple cameras. A detailed articulated human body model composed of sixteen rigid segments that allows both translation and rotation at joints is used. Voxel data of the subject obtained from the images is segmented into the different articulated chains using Laplacian Eigenmaps. The segmented chains are registered in a subset of the frames using a single-frame registration technique and subsequently used to initialize the pose in the sequence. A temporal registration method is proposed to identify the partially segmented or unregistered articulated chains in the remaining frames in the sequence. The proposed tracker uses motion cues such as pixel displacement as well as 2-D and 3-D shape cues such as silhouettes, motion residue, and skeleton curves. The tracking algorithm consists of a predictor that uses motion cues and a corrector that uses shape cues. The use of complementary cues in the tracking alleviates the twin problems of drift and convergence to local minima. The use of multiple cameras also allows us to deal with the problems due to self-occlusion and kinematic singularity. We present tracking results on sequences with different kinds of motion to illustrate the effectiveness of our approach. The pose of the subject is correctly tracked for the duration of the sequence as can be verified by inspection.      

基于目标极化特征的数据关联算法

数据关联是多目标跟踪系统的核心，雷达目标的极化信息虽然不能直接用于目标航迹更新，但可以用来有效区分不同目标和杂波，进而减小量测与航迹关联的不确定性。在获取了目标的极化信息的前提下，根据极化一几何参量综合距离提出广义“最近邻”数据关联算法。仿真结果表明，广义“最近邻”算法性能优于传统的“最近邻”算法。     

MM-CBMeMBer滤波器跟踪多机动目标

多模型(Multiple Model,MM)概率假设密度(Probability Hypothesis Density,PHD)滤波器能同时估计机动目标个数及状态,但其序贯蒙特卡罗(Sequential Monte Carlo,SMC)实现运用粒子聚类算法提取目标状态,不仅引入额外计算量,且可能导致目标丢失。针对这一问题,该文提出一种基于多模型的势平衡无偏多目标多伯努利(Multiple Model Cardinality Balanced Multiple target Multi-Bernoulli,MM-CBMeMBer)滤波器,在每次扫描杂波数低于20,检测概率大于0.9的环境中,该方法利用一组伯努利参数近似机动目标状态的后验概率,并通过对伯努利参数的简单运算估计出目标状态,有效地避免了常规聚类算法。仿真结果表明,该方法与多模型概率假设密度滤波器相比,表征估计误差的最优子模型分配距离明显降低。     

结合多模板的多域卷积神经网络视觉跟踪算法

为了适应视觉跟踪过程中目标外观变化,提高视觉跟踪算法的鲁棒性,本文基于卷积神经网络(Convolutional Neural Network,CNN)并结合多域学习法与多模板管理,提出一种通过树形结构管理多模板的多域卷积神经网络(Multi-Domain CNNs with Multiple Models in a tree structure)视觉跟踪算法.首先使用大量已标记目标位置的视频数据预训练多域结构的CNN,使CNN卷积层可从图像中提取出适用于跟踪任务的特征.然后在跟踪时中对CNN全连接层进行微调以适应跟踪目标,并使用树形结构管理存储不同时间段的目标模板得到模板树.使用模板树综合评价待检测帧,估计目标位置.最后按照一定规则将新模板添加进模板树,完成模板的更新.实验表明,该算法对跟踪过程中目标外观的变化有着良好的适应性,同时多模板可抑制CNN在跟踪时产生的模板漂移问题.     

引入目标径向速度信息的多假设跟踪方法

提出了一种新的基于目标径向速度信息的多假设跟踪算法,来解决边搜索边跟踪雷达系统中数据互联问题,即在SB/MHT算法中,通过引入目标径向速度信息,构造新的航迹置信度公式,完善航迹启动条件。系统仿真结果证明,新算法可有效减少航迹数目,从而缩短系统计算时间,具有更强的抑制虚警的能力。     

多特征融合与尺度估计相结合的目标跟踪算法

针对传统目标跟踪算法判别力及稳健性不足的问题,本文在对跟踪输出响应图可信度进行充分研究的基础上,结合目标尺度估计方法,提出多特征融合和自适应尺度估计相结合的目标跟踪算法.该方法通过计算不同特征模型下的输出响应图可信度,实现对两种互补的特征进行自适应加权融合,有效地提升了表观模型的鉴别力及泛化性能.尺度估计模块通过构建多分辨率特征金字塔、训练尺度滤波器及尺度特征降维,避免了在尺度空间内的穷举式搜索.实验表明文中算法有效地提升了跟踪过程中的准确率和成功率,能够适应遮挡、形变等复杂场景下的目标跟踪,并且具有非常高的效率.     

Multiple Nuclei Tracking Using Integer Programming for Quantitative Cancer Cell Cycle Analysis

Automated cell segmentation and tracking are critical for quantitative analysis of cell cycle behavior using time-lapse fluorescence microscopy. However, the complex, dynamic cell cycle behavior poses new challenges to the existing image segmentation and tracking methods. This paper presents a fully automated tracking method for quantitative cell cycle analysis. In the proposed tracking method, we introduce a neighboring graph to characterize the spatial distribution of neighboring nuclei, and a novel dissimilarity measure is designed based on the spatial distribution, nuclei morphological appearance, migration, and intensity information. Then, we employ the integer programming and division matching strategy, together with the novel dissimilarity measure, to track cell nuclei. We applied this new tracking method for the tracking of HeLa cancer cells over several cell cycles, and the validation results showed that the high accuracy for segmentation and tracking at 99.5% and 90.0%, respectively. The tracking method has been implemented in the cell–cycle analysis software package, DCELLIQ, which is freely available.      

多站无源雷达多起伏目标检测前跟踪算法

针对多站无源雷达背景下多起伏目标同时检测和跟踪的问题,该文提出一种基于多目标多伯努利(MeMBer)滤波器的多起伏目标检测前跟踪(TBD)算法。由于起伏目标的平均信噪比(SNR)未知使得目标的回波幅度似然函数不确定,该文假定包络检波器的输出平均SNR服从先验的均匀分布,并对可能取值区间进行边缘化处理,得到一个估计的似然函数,基于该估计的似然函数,融合中心利用所有收发对的幅度观测信息对MeMBer滤波器的各个预测分量进行更新。仿真结果表明,该算法能够有效地同时检测和跟踪多起伏目标,并且在平均SNR大于9 dB时,其性能与平均SNR已知情况下的性能近似。     

Exploiting Motion Correlations in 3-D Articulated Human Motion Tracking

In 3-D articulated human motion tracking, the curse of dimensionality renders commonly-used particle-filter-based approaches inefficient. Also, noisy image measurements and imperfect feature extraction call for strong motion prior. We propose to learn the correlation between the right-side and the left-side human motion using partial least square (PLS) regression. The correlation effectively constrains the sampling of the proposal distribution to portions of the parameter space that correspond to plausible human motions. The learned correlation is then used as motion prior in designing a Rao–Blackwellized particle filter algorithm, RBPF-PLS, which estimates only one group of state variables using the Monte Carlo method, leaving the other group being exactly computed through an analytical filter that utilizes the learned motion correlation. We quantitatively assessed the accuracy of the proposed algorithm with challenging HumanEva-I/II data set. Experiments with comparison with both the annealed particle filter and the standard particle filter show that the proposed method achieves lower estimation error in processing challenging real-world data of 3-D human motion. In particular, the experiments demonstrate that the learned motion correlation model generalizes well to motions outside of the training set and is insensitive to the choice of the training subjects, suggesting the potential wide applicability of the method.      

Models and Algorithms for Tracking of Maneuvering Objects Using Variable Rate Particle Filters

Standard algorithms in tracking and other state-space models assume identical and synchronous sampling rates for the state and measurement processes. However, real trajectories of objects are typically characterized by prolonged smooth sections, with sharp, but infrequent, changes. Thus, a more parsimonious representation of a target trajectory may be obtained by direct modeling of maneuver times in the state process, independently from the observation times. This is achieved by assuming the state arrival times to follow a random process, typically specified as Markovian, so that state points may be allocated along the trajectory according to the degree of variation observed. The resulting variable dimension state inference problem is solved by developing an efficient variable rate particle filtering algorithm to recursively update the posterior distribution of the state sequence as new data becomes available. The methodology is quite general and can be applied across many models where dynamic model uncertainty occurs on-line. Specific models are proposed for the dynamics of a moving object under internal forcing, expressed in terms of the intrinsic dynamics of the object. The performance of the algorithms with these dynamical models is demonstrated on several challenging maneuvering target tracking problems in clutter.     

Tracking in Wireless Sensor Networks Using Particle Filtering: Physical Layer Considerations

In this paper, a new framework for target tracking in a wireless sensor network using particle filters is proposed. Under this framework, the imperfect nature of the wireless communication channels between sensors and the fusion center along with some physical layer design parameters of the network are incorporated in the tracking algorithm based on particle filters. We call this approach ldquochannel-aware particle filtering.rdquo Channel-aware particle filtering schemes are derived for different wireless channel models and receiver architectures. Furthermore, we derive the posterior Cramer-Rao lower bounds (PCRLBs) for our proposed channel-aware particle filters. Simulation results are presented to demonstrate that the tracking performance of the channel-aware particle filters can reach their theoretical performance bounds even with relatively small number of sensors and they have superior performance compared to channel-unaware particle filters.     

一种机动目标多雷达协同跟踪方法

目标的机动性能不断提高,使得对目标跟踪提出越来越高的要求。针对多部雷达协同探测的目标联合跟踪问题,提出了基于扩展卡尔曼滤波的交互式多模型算法(IMM-EKF)。为了验证算法的有效性,对实测数据进行了处理。首先,对三部雷达接收的目标运动状态量测数据进行预处理,包括坐标转换、线性插值和数据融合,然后,根据数据预处理后目标航迹的特性,采用基于扩展卡尔曼滤波的交互式多模型算法(IMM-EKF)对目标进行在线跟踪。试验数据处理结果表明,IMM-EKF 算法对于机动目标跟踪的有效性。     

Learning Scene Context for Multiple Object Tracking

We propose a framework for multitarget tracking with feedback that accounts for scene contextual information. We demonstrate the framework on two types of context-dependent events, namely target births (i.e., objects entering the scene or reappearing after occlusion) and spatially persistent clutter. The spatial distributions of birth and clutter events are incrementally learned based on mixtures of Gaussians. The corresponding models are used by a probability hypothesis density (PHD) filter that spatially modulates its strength based on the learned contextual information. Experimental results on a large video surveillance dataset using a standard evaluation protocol show that the feedback improves the tracking accuracy from 9% to 14% by reducing the number of false detections and false trajectories. This performance improvement is achieved without increasing the computational complexity of the tracker.      

采用多速率多模型交互实现机动目标的全速率跟踪

多速率模型通过对原始测量结果和目标运动模型进行多分辨分解实现目标高精度跟踪.多模型交互方法则采用一个马尔科夫链控制多个模型交互实现机动目标跟踪.本文给出了一种采用多速率多模型交互方式实现机动目标全速率跟踪的方法,它通过交织多次滤波结果使得跟踪能同时保证高精度和全速率.仿真结果及分析说明了该方法较传统的全速率多模型交互算法获得了更好的跟踪效果.     

复杂场景下基于多特征融合的视频跟踪

为了解决常见视频跟踪方法在复杂场景中难以有效跟踪运动物体的难题,研究了在粒子滤波框架下基于多特征融合的判别式视频跟踪算法.首先分析了特征提取和跟踪算法的鲁棒性和准确性的关系,指出融合多种特征能有效地提升算法在复杂场景中的跟踪效果,然后选择提取HSV颜色特征和HOG特征描述目标表观,并在线训练逻辑斯特回归分类器构造判别式目标表观模型.在公开的复杂场景视频进行测试,比较了使用单一特征和多种特征的实验效果,并且将所提算法和经典跟踪算法进行了比较,实验结果表明融合多种特征的视频跟踪更具鲁棒性和准确性.     

自适应转弯模型的机动目标跟踪算法

给出了一种利用白适应转弯速率模型的IMM跟踪算法，可以用于机动目标的跟踪中。每一步通过交互输出的速度和加速度的估计值来计算转弯速率，它的大小等于加速度和速度的比值。本文中对提出的白适应算法和其他两种IMM算法进行了比较。     

PASTd算法应用于机动多目标角度跟踪

Ryu et al.提出一种基于Kalman滤波和信号子空间的机动多目标角度跟踪算法,在该算法中需要计算信号子空间矩阵W的投影矩阵,因而需要计算N×N维复数逆矩阵.这主要是由于W的列向量间不正交.提出一种用Kahnan滤波预测的角初始化W的方法,使得在用PASTd算法时W能够更快地收敛于列向量为正交向量的矩阵,从而避免了计算N×N维复数逆矩阵,既降低算法的运算量,同时跟踪性能也得到提高.     

地面多目标跟踪滤波技术

介绍了地面运动目标的跟踪滤波算法。计算机仿真及真实雷达环境的多目标跟踪表明,采用本文提出的多目标跟踪处理算法进行地面目标的跟踪,跟踪精度和实时性都能满足要求,该方法是有效和可行的。     

一种用于多目标跟踪的增强型SMC-PHD 滤波算法

该文对标准型SMC-PHD 滤波器作了两点改进。第一,提出基于观测值的目标个数和目标状态估计方法,该方法首先计算以观测值为行、存活粒子为列的权值矩阵,将按行计算的权值和与判决门限比较,把大于门限的观测值判决为真实观测值,并据此估算目标个数和目标状态。第二,为每个粒子分配表示存活年龄的辅助变量,以抑制强杂波环境下的目标数高估问题。仿真实验表明,在强杂波环境下,增强型SMC-PHD 算法在多目标跟踪稳定性方面优于标准型SMC-PHD 算法。