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.     

融合灰度和SURF特征的红外目标跟踪

由于红外图像对比度低、色彩信息匮乏且灰度级动态范围小,基于红外成像的目标跟踪一直是本领域研究的难点和重点。提出了一种融合灰度核直方图和SURF(speeded up robust features)特征的红外目标跟踪算法。在首帧采用灰度核直方图和SURF特征分别描述目标模板,在以后每帧中利用均值漂移算法快速找到局部最优解。考虑到灰度直方图特征信息量少,跟踪误差逐渐累积,采用改进的SURF特征点匹配算法估算当前帧目标尺度和中心位置,及时修正累积误差,避免跟踪窗口漂移且能自适应调整跟踪窗口大小,此外更新目标模板,最终准确跟踪目标。真实场景实验结果表明,本文算法在目标外观发生较大尺度变化、周边具有相似表观物体时能稳定跟踪目标,具有很强的稳健性,且满足实时性要求。     

A probabilistic integrated object recognition and tracking framework

This paper describes a probabilistic integrated object recognition and tracking framework called PIORT, together with two specific methods derived from it, which are evaluated experimentally in several test video sequences. The first step in the proposed framework is a static recognition module that provides class probabilities for each pixel of the image from a set of local features. These probabilities are updated dynamically and supplied to a tracking decision module capable of handling full and partial occlusions. The two specific methods presented use RGB color features and differ in the classifier implemented: one is a Bayesian method based on maximum likelihood and the other one is based on a neural network. The experimental results obtained have shown that, on one hand, the neural net based approach performs similarly and sometimes better than the Bayesian approach when they are integrated within the tracking framework. And on the other hand, our PIORT methods have achieved better results when compared to other published tracking methods in video sequences taken with a moving camera and including full and partial occlusions of the tracked object.     

基于SURF和CamShift的物体跟踪方法

CamShift算法是一种常用的跟踪算法,但是它只利用颜色特征来进行目标跟踪,当背景颜色与跟踪目标的颜色相似时会出现跟踪失败的情况。结合SURF设计了一种基于SURF和CamShift算法的创新的跟踪方法。利用反馈机制计算CamShift跟踪窗口与初始窗口的特征相似度以及SURF跟踪窗口与初始窗口的色彩相似度;同时抑制大的位移变化,为两种跟踪算法动态分配位移的权重,以实现对物体的跟踪。测试实验表明,该跟踪方法对不同的物体、在不同的环境下有较好的效果。     

改进STC和SURF特征联合优化的目标跟踪算法

针对传统时空上下文目标跟踪(STC)算法中目标窗口不能适应目标尺度变化,导致对目标针对性不强等问题,提出改进STC和SURF特征联合优化的目标跟踪算法(STC-SURF)。首先利用加速稳健(SURF)特征算法对相邻的2帧图像提取特征点并进行匹配,再通过随机抽样一致(RANSAC)算法消除误匹配,提高匹配精度。进而根据2帧图像中匹配特征点的变化对目标窗口进行调整。最终对STC算法中模型的更新方式进行优化以提高跟踪结果的准确性。实验结果表明,STC-SURF算法能够适应目标尺度变化,并且其目标跟踪成功率优于TLD算法和传统STC算法的。     

基于改进Mean Shift和SURF的目标跟踪

传统颜色直方图的Mean Shift（MS）算法只考虑了目标颜色的统计信息,不包含目标的空间信息,当目标颜色与背景颜色相近或目标对象发生光照变化时,容易导致不准确跟踪或跟踪丢失。针对该问题,提出了一种融合改进MS和SURF的跟踪算法。改进的MS算法根据目标对象的最新外接矩形尺寸,确定对象的分块方法,根据各块的Bhattacharyya系数值,确定各块的权重系数,获得初步的跟踪结果;采用SURF特征匹配和校正的方法对其初步跟踪结果进行调整;采用线性加权的方法融合改进的MS和SURF跟踪结果,得出最终的跟踪结果。实验表明,提出的融合改进MS和SURF的跟踪算法,比传统的MS算法和固定分块的MS算法都具有更好的跟踪性能。     

Visual object tracking via sample-based Adaptive Sparse Representation (AdaSR)

When appearance variation of object and its background, partial occlusion or deterioration in object images occurs, most existing visual tracking methods tend to fail in tracking the target. To address this problem, this paper proposes a new approach for visual object tracking based on Sample-Based Adaptive Sparse Representation (AdaSR), which ensures that the tracked object is adaptively and compactly expressed with predefined samples. First, the Sample-Based Sparse Representation, which selects a subset of samples as a basis for object representation by exploiting L1-norm minimization, improves the representation adaptation to partial occlusion for tracking. Second, to keep the temporal consistency and adaptation to appearance variation and deterioration in object images during the tracking process, the object's Sample-Based Sparse Representation is adaptively evaluated based on a Kalman filter, obtaining the AdaSR. Finally, the candidate holding the most similar Sample-Based Sparse Representation to the AdaSR of the tracked object will be regarded as the instantaneous tracking result. In addition, we can easily extend the AdaSR for multi-object tracking by integrating the sample set of each tracked object (named Common Sample-Based Adaptive Sparse Representation Analysis (AdaSRA)). AdaSRA fully analyses Adaptive Sparse Representation similarity for object classification. Our experiments on public datasets show state-of-the-art results, which are better than those of several representative tracking methods.     

一种抗视角变换的SURF匹配算法

针对传统的SURF匹配算法在图像搜索、物体识别中对视角变化大的图像特征点无法匹配的缺陷,提出了一种改进的SURF图像匹配算法。该算法利用模拟图序列的概念,即由原始图像模拟各种可能的视角变换生成的一组图像序列,对图像序列中的每幅图像进行SURF特征点提取;剔除冗余特征点后将模拟图序列中的特征点映射到原始图像中,这一过程增加了原始图像的特征点数量,特征点描述向量改用原始图像和多个模拟图的SURF特征描述向量共同表示;最后采用欧氏距离准则,最终得到两幅图像的正确匹配对。实验结果表明,本算法增加了特征点匹配对数,改善了视角变换过大(大于60°)使得图像无法匹配的情况。     

多支持向量机在线联合的运动目标跟踪算法

依据二元分类的思想,提出了一种新的基于多支持向量机在线联合的运动目标跟踪算法。首先选择线性支持向量机作为分类器最大限度地将目标和背景区分开来,对线性支持向量机进行简单高效的在线更新,采用支持向量自动记录运动目标 “关键帧”的信息。然后通过Adaboost算法为每个线性支持向量机分别赋以不同的权重,进行在线联合获得强分类器。实验结果表明,该算法具有较强的鲁棒性,尤其在目标变化过于激烈的情况下能够实现较为稳定的跟踪。     

基于改进的SURF图像配准算法研究

图像特征点匹配算法是实现目标识别的一种有效算法,目前图像特征点匹配算法耗时大,而且在匹配过程中存在伪匹配点。提出了一种改进算法：在初始特征点检测阶段,根据图像大小动态构造高斯金字塔图层,提高了算法的实时性和准确性;采用设置阈值的方法对初始特征点进行优化,减少匹配时间。在特征点匹配阶段,利用提取特征点中正确匹配点与伪匹配点坐标值差异较大这种特性,对伪匹配点进行去除,最后进行目标识别。实验结果表明,在尺寸大小为800×600的图像中,SURF算法提取特征点数225个,耗时92.499 ms, Octave 3;特征点匹配率97.50% ,耗时349.716 ms。提出的改进方法更为简单有效,减少了特征点匹配的误差,能够有效缩短图像配准时间。     

一种基于模板匹配的运动目标跟踪方法

为了提高运动目标跟踪算法在复杂场景下的稳定性,提出了一种将小波变换与模扳匹配相融合的跟踪方法。它首先对图像序列采用滤波器组实现运动目标分割,再通过对图像序列小波变换以确定目标匹配子图像,最终使用模板匹配求取最佳匹配点来实现实时跟踪。采用MATLAB仿真实验,对标准视频序列coastguard_cif实验测试结果表明,提出的方法具有良好的跟踪性能。     

基于置信度策略选择的实时目标跟踪方法

目标跟踪一直是计算机视觉领域研究的热点和难点,受自然场景中复杂干扰因素影响,现有方法的速度和精度尚待改善。本文首先对基于颜色属性的目标跟踪算法改进,使之更为鲁棒且速度达到实时。接下来,针对被跟踪目标发生遮挡时,采用基于颜色属性的跟踪算法导致错误累积进而产生漂移甚至跟踪失败的问题,引入运算量较大但对遮挡有较强抵抗能力的稀疏协作表观模型。为了同时保证算法的速度和准确性,本文构建了一套基于跟踪结果置信度评量的策略选择机制,将两种算法有机整合。在多个公开数据集下的对比实验显示,与现有跟踪算法相比,本文方法在跟踪效果和速度上具有较显著优势,并在目标存在严重遮挡、光照变化、运动模糊等情况时,均可以取得较好的跟踪效果。     

A visual attention model for robot object tracking

Inspired by human behaviors, a robot object tracking model is proposed on the basis of visual attention mechanism, which is fit for the theory of topological perception. The model integrates the image-driven, bottom-up attention and the object-driven, top-down attention, whereas the previous attention model has mostly focused on either the bottom-up or top-down attention. By the bottom-up component, the whole scene is segmented into the ground region and the salient regions. Guided by top-down strategy which is achieved by a topological graph, the object regions are separated from the salient regions. The salient regions except the object regions are the barrier regions. In order to estimate the model, a mobile robot platform is developed, on which some experiments are implemented. The experimental results indicate that processing an image with a resolution of 752*480 pixels takes less than 200ms and the object regions are unabridged. The analysis obtained by comparing the proposed model with the existing model demonstrates that the proposed model has some advantages in robot object tracking in terms of speed and efficiency.     

基于改进的颜色和SURF特征的粒子滤波目标跟踪

针对视频中运动目标的准确跟踪问题,提出了一种改进的颜色直方图特征和SURF特征的粒子滤波跟踪算法。采用SURF算法提取特征点,利用分层迭代的KLT算法对特征点进行稳定跟踪。将SURF特征与改进的视觉显著性颜色特征进行乘性融合,作为粒子滤波的观测概率。针对跟踪过程中SURF匹配数下降和不稳定的现象,设计了SURF特征模板集的更新策略。与传统特征的跟踪进行多组对比实验,其结果证明了该方法对光照和遮挡具有很好的鲁棒性,对目标跟踪的准确率更高。     

基于TLD框架的快速目标跟踪方法

现实中目标在被长期跟踪时容易发生形变、遮挡、光照干扰以及其它问题,现有跟踪算法虽能解决该系列问题但算法计算量巨大导致跟踪系统实时性能较差,很难应用于实际场合。因此准确快速跟踪目标成为近年来非常有挑战的热点课题。以国外学者Zdenek Kalal等人提出的TLD(Tracking-Learning-Detection)框架为基础,提出了三点改进方法。一根据目标所占整幅图像的面积大小动态调整被处理图像的分辨率,从总体上减少样本数量;二在目标邻近区域扫描生成样本,缩小检测器的检测范围;三更换检测部分中分类器模板匹配方法,实现快速匹配,提高算法运行速度。针对与不同的场景,实验表明上述问题在改进后的算法中得到了较大的改善,算法的计算量有效降低,系统运行速度得到提高。且对于实时摄像头监控,改进后算法在保证目标跟踪准确率的同时拥有较好的实时性。     

Accurate object contour tracking based on boundary edge selection

In this paper, a novel method for accurate subject tracking, by selecting only tracked subject boundary edges in a video stream with a changing background and moving camera, is proposed. This boundary edge selection is achieved in two steps: (1) removing background edges using edge motion, and from the output of the previous step, (2) selecting boundary edges using a normal direction derivative of the tracked contour. Accurate tracking is based on reduction of the effects of irrelevant edges, by only selecting boundary edge pixels. In order to remove background edges using edge motion, the tracked subject motion is computed and edge motions and edges having different motion directions from the subjects are removed. In selecting boundary edges using the normal contour direction, the image gradient values on every edge pixel are computed, and edge pixels with large gradient values are selected. Multi-level Canny edge maps are used to obtain proper details of a scene. Multi-level edge maps allow tracking, even though the tracked object boundary has complex edges, since the detail level of an edge map for the scene can be adjusted. A process of final routing is deployed in order to obtain a detailed contour. The computed contour is improved by checking against a strong Canny edge map and hiring strong Canny edge pixels around the computed contour using Dijkstra's minimum cost routing. The experimental results demonstrate that the proposed tracking approach is robust enough to handle a complex-textured scene in a mobile camera environment.     

基于运动区域检测的运动目标跟踪算法*

针对传统基于模板匹配的运动目标跟踪算法存在着计算量大、模板漂移导致跟踪失败的问题,提出了一种基于运动区域检测的运动目标跟踪算法。该算法通过采用光流法对目标运动区域进行估计,计算出光流场区域的形心,确定待匹配图相匹配范围,再用模板框在已确定区域进行模板匹配跟踪。根据某开放实验室行人录像跟踪实验表明,本算法能够有效解决模板漂移问题,提高了跟踪实时性, 实现了视频对象目标的跟踪。     

A unified learning framework for object detection and classification using nested cascades of boosted classifiers

In this paper a unified learning framework for object detection and classification using nested cascades of boosted classifiers is proposed. The most interesting aspect of this framework is the integration of powerful learning capabilities together with effective training procedures, which allows building detection and classification systems with high accuracy, robustness, processing speed, and training speed. The proposed framework allows us to build state of the art face detection, eyes detection, and gender classification systems. The performance of these systems is validated and analyzed using standard face databases (BioID, FERET and CMU-MIT), and a new face database (UCHFACE).

基于Mean Shift的相似性变换和仿射变换目标跟踪算法

传统的Mean Shift (MS) 算法只能对发生平移和尺度变化的目标进行跟踪,而对于具有相似性变换或者更复杂的仿射变换的目标跟踪效果很不理想或无法跟踪。为了解决这一问题,提出了两种基于MS的改进算法。第一种算法针对仿射变换,根据奇异值分解理论,仿射变换矩阵可以分解成两个旋转矩阵和一个对角矩阵的乘积,在此基础上建模了一种新的候选目标模型。通过Bhattacharyya系数将目标跟踪问题转化成以仿射变换参数为变量的最优化问题,推导相关参量的一阶偏导数并令其为零从而得出相对于仿射变换的MS算法。另外,针对进行相似性变换的目标也提出了一种新的候选目标模型,并用类似的梯度下降算法估计目标的平移向量和旋转角度。实验结果表明,提出的算法能够跟踪具有相似性变换或仿射变换的目标,比传统的MS算法具有更好的跟踪性能。