Smooth foreground-background segmentation for video processing

We propose an efficient way to account for spatial smoothness in foreground-background segmentation of video sequences. Most statistical background modeling techniques regard the pixels in an image as independent. and disregard the fundamental concept of smoothness. In contrast, we model smoothness of the foreground and background with a Markov random field, in such a way that it can be globally optimized at video frame rate. As a background model, the mixture-of-Gaussian (MOG) model is adopted and enhanced with several improvements developed for other background models. Experimental results show that the MOG model is still competitive, and that segmentation with the smoothness prior outperforms other methods

Recent Advances on Supervised Distance Metric Learning Algorithms

近年来,距离度量学习已成为计算机视觉和模式识别等领域最为活跃的研究课题之一.如何利用训练数据学习得到有效的距离度量来衡量目标之间的相似性是该类研究的关键问题.针对有监督的距离度量学习问题,目前已提出了大量的研究算法.结合近年已发表相关文献对有监督的距离度量学习算法进行了详细的介绍和讨论.根据样本信息利用方式的不同,将其划分成基于成对约束和非成对约束的距离度量学习算法,重点介绍了一些常用的典型算法,分析了每种算法的原理和优缺点,最后是未来发展方向和趋势的展望.Recently, distance metric learning has become one of the most attractive research areas in computer vision and pattern recognition.How to learn an effective distance metric to measure the similarity between subjects is a key problem.A large number of algorithms have been proposed to deal with supervised distance metric learning.This paper reviews and discusses recently developed algorithms for supervised distance metric learning.Based on the partition of pairwise constraints and non-pairwise constraints, some representative algorithms are introduced and their respective pros and cons are analyzed.The prospects for future development and suggestions for further research work are presented in the end.国家自然科学基金(61201359;61170179); 福建省自然科学基金(2012J05126); 高等学校博士学科点专项科研基金(20110121110033)资助~

Generalized Kernel-Based Visual Tracking

Kernel-based mean shift (MS) trackers have proven to be a promising alternative to stochastic particle filtering trackers. Despite its popularity, MS trackers have two fundamental drawbacks: 1) the template model can only be built from a single image, and 2) it is difficult to adaptively update the template model. In this paper, we generalize the plain MS trackers and attempt to overcome these two limitations. It is well known that modeling and maintaining a representation of a target object is an important component of a successful visual tracker. However, little work has been done on building a robust template model for kernel-based MS tracking. In contrast to building a template from a single frame, we train a robust object representation model from a large amount of data. Tracking is viewed as a binary classification problem, and a discriminative classification rule is learned to distinguish between the object and background. We adopt a support vector machine for training. The tracker is then implemented by maximizing the classification score. An iterative optimization scheme very similar to MS is derived for this purpose. Compared with the plain MS tracker, it is now much easier to incorporate online template adaptation to cope with inherent changes during the course of tracking. To this end, a sophisticated online support vector machine is used. We demonstrate successful localization and tracking on various data sets

Adaptive object tracking based on an effective appearance filter

We propose a similarity measure based on a Spatial-color Mixture of Gaussians (SMOG) appearance model for particle filters. This improves on the popular similarity measure based on color histograms because it considers not only the colors in a region but also the spatial layout of the colors. Hence, the SMOG-based similarity measure is more discriminative. To efficiently compute the parameters for SMOG, we propose a new technique with which the computational time is greatly reduced. We also extend our method by integrating multiple cues to increase the reliability and robustness. Experiments show that our method can successfully track objects in many difficult situations

Linear discriminant analysis using rotational invariant L-1 norm

Linear discriminant analysis (LDA) is a well-known scheme for supervised subspace learning. It has been widely used in the applications of computer vision and pattern recognition. However, an intrinsic limitation of LDA is the sensitivity to the presence of outliers, due to using the Frobenius norm to measure the inter-class and intra-class distances. In this paper, we propose a novel rotational invariant L-1 norm (i.e., R-1 norm) based discriminant criterion (referred to as DCL1), which better characterizes the intra-class compactness and the inter-class separability by using the rotational invariant L-1 norm instead of the Frobenius norm. Based on the DCL1, three subspace learning algorithms (i.e., 1DL(1), 2DL(1), and TDL1) are developed for vector-based, matrix-based, and tensor-based representations of data, respectively. They are capable of reducing the influence of outliers substantially, resulting in a robust classification. Theoretical analysis and experimental evaluations demonstrate the promise and effectiveness of the proposed DCL1 and its algorithms. (C) 2010 Elsevier B.V. All rights reserved

基于偏好统计数据表征的鲁棒几何模型拟合方法

鲁棒几何模型拟合是计算机视觉的一个基础性研究问题,广泛应用于各类计算机视觉任务,如单应性矩阵或基础矩阵估计、图像匹配、医学图像分析等。它的主要任务是:在包含噪声点和离群点的数据集中估计模型实例的参数和个数。针对该任务,本文提出一种基于新型数据表征(称之为偏好统计数据表征)的模型拟合方法。该新型数据表征算法将残差值进行排序然后映射到不同的区间以构建残差直方图数据表征,来描述数据分布的特征。该算法充分利用传统模型拟合方法中偏好分析和一致性统计分析的优点,更加有效地对数据分布特征进行描述,从而有效地提高数据表征的准确性和鲁棒性。为了进一步有效地利用该数据表征中的统计信息(内点和离群点显示出显著的信息熵值差异),本文利用直方图中不同区间段所映射的残差值的出现频次,以分析直方图的特性。并且采用一种简单的自适应熵阈值算法,来区分内点与离群点以进行离群点检测。最后,为了能够更好地处理分布在交叉模型实例附近的数据点,本文引入一种基于相似矩阵学习的图聚类技术,提出一个有效的模型实例估计算法。该算法先是用聚类技术以实现数据的分割,进而估计模型实例的参数。同时,该模型实例估计算法结合拉普拉斯矩阵特征值的分析..

Visual tracking with spatio-temporal Dempster-Shafer information fusion

A key problem in visual tracking is how to effectively combine spatio-temporal visual information from throughout a video to accurately estimate the state of an object. We address this problem by incorporating Dempster-Shafer information fusion into the tracking approach. To implement this fusion task, the entire image sequence is partitioned into spatially and temporally adjacent subsequences. A support vector machine (SVM) classifier is trained for object=non-object classification on each of these subsequences, the outputs of which act as separate data sources. To combine the discriminative information from these classifiers, we further present a spatio-temporal weighted Dempster-Shafer (STWDS) scheme. Moreover, temporally adjacent sources are likely to share discriminative information on object/non-object classification. In order to use such information, an adaptive SVM learning scheme is designed to transfer discriminative information across sources. Finally, the corresponding Dempster-Shafer belief function of the STWDS scheme is embedded into a Bayesian tracking model. Experimental results on challenging videos demonstrate the effectiveness and robustness of the proposed tracking approach.Xi Li, Anthony Dick, Chunhua Shen, Zhongfei Zhang, Anton van den Hengel, Hanzi Wan

深度学习的目标跟踪算法综述

目标跟踪是利用一个视频或图像序列的上下文信息,对目标的外观和运动信息进行建模,从而对目标运动状态进行预测并标定目标位置的一种技术,是计算机视觉的一个重要基础问题,具有重要的理论研究意义和应用价值,在智能视频监控系统、智能人机交互、智能交通和视觉导航系统等方面具有广泛应用。大数据时代的到来及深度学习方法的出现,为目标跟踪的研究提供了新的契机。本文首先阐述了目标跟踪的基本研究框架,从观测模型的角度对现有目标跟踪的历史进行回顾,指出深度学习为获得更为鲁棒的观测模型提供了可能;进而从深度判别模型、深度生成式模型等方面介绍了适用于目标跟踪的深度学习方法;从网络结构、功能划分和网络训练等几个角度对目前的深度目标跟踪方法进行分类并深入地阐述和分析了当前的深度目标跟踪方法;然后,补充介绍了其他一些深度目标跟踪方法,包括基于分类与回归融合的深度目标跟踪方法、基于强化学习的深度目标跟踪方法、基于集成学习的深度目标跟踪方法和基于元学习的深度目标跟踪方法等;之后,介绍了目前主要的适用于深度目标跟踪的数据库及其评测方法;接下来从移动端跟踪系统,基于检测与跟踪的系统等方面深入分析与总结了目标跟踪中的最新具体应用情况,最后对深度学习方法在目标跟踪中存在的训练数据不足、实时跟踪和长程跟踪等问题进行分析,并对未来的发展方向进行了展望。国家自然科学基金项目(U1605252,61872307,61773397)~

Adaptive scale based entropy-like estimator for robust fitting

Conference Name:2013 38th IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2013. Conference Address: Vancouver, BC, Canada. Time:May 26, 2013 - May 31, 2013.IEE Signal Processing SocietyIn this paper, we propose a novel robust estimator, called ASEE (Adaptive Scale based Entropy-like Estimator) which minimizes the entropy of inliers. This estimator is based on IKOSE (Iterative Kth Ordered Scale Estimator) and LEL (Least Entropy-Like Estimator). Unlike LEL, ASEE only considers inliers' entropy while excluding outliers, which makes it very robust in parametric model estimation. Compared with other robust estimators, ASEE is simple and computationally efficient. From the experiments on both synthetic and real-image data, ASEE is more robust than several state-of-the-art robust estimators, especially in handling extreme outliers. ? 2013 IEEE

A consensus-based method for tracking: Modelling background scenario and foreground appearance

Modelling of the background ("uninteresting parts of the scene"), and of the foreground, play important roles in the tasks of visual detection and tracking of objects. This paper presents an effective and adaptive background modelling method for detecting foreground objects in both static and dynamic scenes. The proposed method computes SAmple CONsensus (SACON) of the background samples and estimates a statistical model of the background, per pixel. SACON exploits both color and motion information to detect foreground objects. SACON can deal with complex background scenarios including nonstationary scenes (such as moving trees, rain, and fountains), moved/inserted background objects, slowly moving foreground objects, illumination changes etc. However, it is one thing to detect objects that are not likely to be part of the background; it is another task to track those objects. Sample consensus is again utilized to model the appearance of foreground objects to facilitate tracking. This appearance model is employed to segment and track people through occlusions. Experimental results from several video sequences validate the effectiveness of the proposed method. (c) 2006 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved