A General Method for Sensor Planning in Multi-Sensor Systems: Extension to Random Occlusion

Systems utilizing multiple sensors are required in many domains. In this paper, we specifically concern ourselves with applications where dynamic objects appear randomly and the system is employed to obtain some user-specified characteristics of such objects. For such systems, we deal with the tasks of determining measures for evaluating their performance and of determining good sensor configurations that would maximize such measures for better system performance. We introduce a constraint in sensor planning that has not been addressed earlier: visibility in the presence of random occluding objects. occlusion causes random loss of object capture from certain necessitates the use of other sensors that have visibility of this object. Two techniques are developed to analyze such visibility constraints: a probabilistic approach to determine “average” visibility rates and a deterministic approach to address worst-case scenarios. Apart from this constraint, other important constraints to be considered include image resolution, field of view, capture orientation, and algorithmic constraints such as stereo matching and background appearance. Integration of such constraints is performed via the development of a probabilistic framework that allows one to reason about different occlusion events and integrates different multi-view capture and visibility constraints in a natural way. Integration of the thus obtained capture quality measure across the region of interest yields a measure for the effectiveness of a sensor configuration and maximization of such measure yields sensor configurations that are best suited for a given scenario. The approach can be customized for use in many multi-sensor applications and our contribution is especially significant for those that involve randomly occurring objects capable of occluding each other. These include security systems for surveillance in public places, industrial automation and traffic monitoring. Several examples illustrate such versatility by application of our approach to a diverse set of different and sometimes multiple system objectives. Most of this work was done while A. Mittal was with Real-Time Vision and Modeling Department, Siemens Corporate Research, Princeton, NJ 08540.     

基于监控系统的人体行为识别技术研究

针对传统行为识别技术实时性、鲁棒性较差等问题,提出了一种高效鲁棒性的人体行为识别算法。通过基于Meanshift和Kalman滤波相结合的跟踪算法来跟踪定位人体目标;利用肢体特征和区域特征来提取运动特征;利用基于OAA的支持向量机分类识别。仿真实验表明,该算法实时性好、鲁棒性高,能有效应用于监控系统中。     

基于MPEG-4的嵌入式IP网络监控摄像系统

基于MPEG4的嵌入式IP网络监控摄像系统是将智能摄像机与数字化和压缩芯片集成为一体的嵌入式视频采集及网络传输系统。采用了数字图像处理技术、MPEG-4数字音视频压缩技术、嵌入式操作系统及嵌入式操作系统软件开发技术、符合工业标准的应用接口开发技术、计算机网络通信技术等多种先进技术。     

Camera handoff with adaptive resource management for multi-camera multi-object tracking

Camera handoff is a crucial step to obtain a continuously tracked and consistently labeled trajectory of the object of interest in multi-camera surveillance systems. Most existing camera handoff algorithms concentrate on data association, namely consistent labeling, where images of the same object are identified across different cameras. However, there exist many unsolved questions in developing an efficient camera handoff algorithm. In this paper, we first design a trackability measure to quantitatively evaluate the effectiveness of object tracking so that camera handoff can be triggered timely and the camera to which the object of interest is transferred can be selected optimally. Three components are considered: resolution, distance to the edge of the camera’s field of view (FOV), and occlusion. In addition, most existing real-time object tracking systems see a decrease in the frame rate as the number of tracked objects increases. To address this issue, our handoff algorithm employs an adaptive resource management mechanism to dynamically allocate cameras’ resources to multiple objects with different priorities so that the required minimum frame rate is maintained. Experimental results illustrate that the proposed camera handoff algorithm can achieve a substantially improved overall tracking rate by 20% in comparison with the algorithm presented by Khan and Shah.     

多层分类器模型的相似人体活动识别

针对基于单传感器活动识别中相似活动易混淆的问题,本文提出了一种基于广义判别分析的多层分类器融合的相似人体活动识别算法.首先提取基于单加速度计的多类活动数据的时域特征、频域特征以及时频特征,对不同特征进行特征分析与重要性评估以确定有效的特征维度.使用随机森林(RF,Random forest)算法对活动特征进行第1层分类...     

基于全景视觉的监控系统设计

设计了一个基于全景视觉的多摄像机监控网络。全景相机视野广,可以实现大范围的目标检测与跟踪。云台摄像机视角具有一定的自由度,可以捕捉目标的高分辨率图像。将全景相机与云台相机相互配合,通过多传感器的数据融合,分层次的跟踪算法及多相机调度算法,实现了大范围的多个运动目标的检测与跟踪,并能捕获目标的清晰图像。实验验证了该系统的有效性和合理性。     

浅谈网络摄像机在污水处理厂中的应用

视频监控系统是污水处理厂一个重要的子系统,监视对象主要是工艺设施、重要设备、变电所和主要道路,对污水厂的运行、维护、安防有着重要的意义。本文对视频监控系统中的模拟摄像机和网络摄像机做了一个简单的对比,并对于网络摄像机应用于污水处理厂的合理性进行一定的探讨和研究。     

基于智能手机传感器的人体行为识别技术研究与实践

本文首先介绍了一种基于智能手机传感器获取加速度等数据的App设计方法,设定了15种需要识别的动作、手机位置组合类别,收集了75万条运动数据记录;其次,采用滑动窗口技术分割时序数据,构建了有针对性的时域、频域特征指标,形成了不同窗口大小、步长的新样本系列;最后,通过分类结果筛选出性能优良的4类算法,证实了深度学习在特征构...     

Early detection of human actions—A hybrid approach

Early detection of human actions is essential in a wide spectrum of applications ranging from video surveillance to health-care. While human action recognition has been extensively studied, little attention is paid to the problem of detecting ongoing human action early, i.e. detecting an action as soon as it begins, but before it finishes. This study aims at training a detector to be capable of recognizing a human action when only partial action sample is seen. To do so, a hybrid technique is proposed in this work which combines the benefits of computer vision as well as fuzzy set theory based on the fuzzy Bandler and Kohout's sub-triangle product (BK subproduct). The novelty lies in the construction of a frame-by-frame membership function for each kind of possible movement. Detection is triggered when a pre-defined threshold is reached in a suitable way. Experimental results on a publicly available dataset demonstrate the benefits and effectiveness of the proposed method.     

Human tracking using 3D surface colour distributions

A likelihood formulation for detailed human tracking in real-world scenes is presented. In this formulation, the appearance, modelled using feature distributions defined over regions on the surface of an articulated 3D model, is estimated and propagated as part of the state. The benefit of such a formulation over currently used techniques is that it provides a dense, highly discriminatory object-based cue that applies in real world scenes. Multi-dimensional histograms are used to represent the feature distributions and an on-line clustering algorithm, driven by prior knowledge of clothing structure, is derived that enhances appearance estimation and computational efficiency. An investigation of the likelihood model shows its profile to be smooth and broad while region grouping is shown to improve localisation and discrimination. These properties of the likelihood model ease pose estimation by allowing coarse, hierarchical sampling and local optimisation.     

Human action recognition using boosted EigenActions

This paper proposes a boosting EigenActions algorithm for human action recognition. A spatio-temporal Information Saliency Map (ISM) is calculated from a video sequence by estimating pixel density function. A continuous human action is segmented into a set of primitive periodic motion cycles from information saliency curve. Each cycle of motion is represented by a Salient Action Unit (SAU), which is used to determine the EigenAction using principle component analysis. A human action classifier is developed using multi-class Adaboost algorithm with Bayesian hypothesis as the weak classifier. Given a human action video sequence, the proposed method effectively locates the SAUs in the video, and recognizes the human actions by categorizing the SAUs. Two publicly available human action databases, namely KTH and Weizmann, are selected for evaluation. The average recognition accuracy are 81.5% and 98.3% for KTH and Weizmann databases, respectively. Comparative results with two recent methods and robustness test results are also reported.     

Human activity recognition using multi-features and multiple kernel learning

This paper presents two sets of features, shape representation and kinematic structure, for human activity recognition using a sequence of RGB-D images. The shape features are extracted using the depth information in the frequency domain via spherical harmonics representation. The other features include the motion of the 3D joint positions (i.e. the end points of the distal limb segments) in the human body. Both sets of features are fused using the Multiple Kernel Learning (MKL) technique at the kernel level for human activity recognition. Our experiments on three publicly available datasets demonstrate that the proposed features are robust for human activity recognition and particularly when there are similarities among the actions.     

Human activity recognition in pervasive health-care: Supporting efficient remote collaboration

Technological advancements, including advancements in the medical field have drastically improved our quality of life, thus pushing life expectancy increasingly higher. This has also had the effect of increasing the number of elderly population. More than ever, health-care institutions must now care for a large number of elderly patients, which is one of the contributing factors in the rising health-care costs. Rising costs have prompted hospitals and other health-care institutions to seek various cost-cutting measures in order to remain competitive. One avenue being explored lies in the technological advancements that can make hospital working environments much more efficient. Various communication technologies, mobile computing devices, micro-embedded devices and sensors have the ability to support medical staff efficiency and improve health-care systems. In particular, one promising application of these technologies is towards deducing medical staff activities. Having this continuous knowledge about health-care staff activities can provide medical staff with crucial information of particular patients, interconnect with other supporting applications in a seamless manner (e.g. a doctor diagnosing a patient can automatically be sent the patient's lab report from the pathologist), a clear picture of the time utilisation of doctors and nurses and also enable remote virtual collaboration between activities, thus creating a strong base for establishment of an efficient collaborative environment. In this paper, we describe our activity recognition system that in conjunction with our efficiency mechanism has the potential to cut down health-care costs by making the working environments more efficient. Initially, we outline the activity recognition process that has the ability to infer user activities based on the self-organisation of surrounding objects that user may manipulate. We then use the activity recognition information to enhance virtual collaboration in order to improve overall efficiency of tasks within a hospital environment. We have analysed a number of medical staff activities to guide our simulation setup. Our results show an accurate activity recognition process for individual users with respect to their behaviour. At the same time we support remote virtual collaboration through tasks allocation process between doctors and nurses with results showing maximum efficiency within the resource constraints.     

实时跟踪系统中运动人体图像分割

在视频序列的人体运动分析中,实时分割出运动的人体,是研究的起始关键步骤。该文在简单的运用差图像算法进行人体运动检测的基础上,结合直方图自动阈值分割和数学形态学的算法来完成运动人体的精确分割。实验结果表明上述算法对噪声抑制和人体图像断裂处填充都是有效的,能够实时分割完成运动人体的视频图像。     

Pedestrian detection and tracking at crossroads

This paper presents a system that can perform pedestrian detection and tracking using vision-based techniques. A very important issue in the field of intelligent transportation system is to prevent pedestrians from being hit by vehicles. Recently, a great number of vision-based techniques have been proposed for this purpose. In this paper, we propose a vision-based method, which combines the use of a pedestrian model as well as the walking rhythm of pedestrians to detect and track walking pedestrians. Through integrating some spatial and temporal information grabbed by a vision system, we are able to develop a reliable system that can be used to prevent traffic accidents happened at crossroads. In addition, the proposed system can deal with the occlusion problem. Experimental results obtained by executing some real world cases have demonstrated that the proposed system is indeed superb.     

Human action recognition based on skeleton splitting

Human action recognition, defined as the understanding of the human basic actions from video streams, has a long history in the area of computer vision and pattern recognition because it can be used for various applications. We propose a novel human action recognition methodology by extracting the human skeletal features and separating them into several human body parts such as face, torso, and limbs to efficiently visualize and analyze the motion of human body parts.Our proposed human action recognition system consists of two steps: (i) automatic skeletal feature extraction and splitting by measuring the similarity between neighbor pixels in the space of diffusion tensor fields, and (ii) human action recognition by using multiple kernel based Support Vector Machine. Experimental results on a set of test database show that our proposed method is very efficient and effective to recognize the actions using few parameters.     

Understanding human behavior from motion imagery

Computer vision is gradually making the transition from image understanding to video understanding. This is due to the enormous success in analyzing sequences of images that has been achieved in recent years. The main shift in the paradigm has been from recognition followed by reconstruction (shape from X) to motion-based recognition. Since most videos are about people, this work has focused on the analysis of human motion. In this paper, I present my perspective on understanding human behavior. Automatically understanding human behavior from motion imagery involves extraction of relevant visual information from a video sequence, representation of that information in a suitable form, and interpretation of visual information for the purpose of recognition and learning about human behavior. Significant progress has been made in human tracking over the last few years. As compared with tracking, not much progress has been made in understanding human behavior, and the issue of representation has largely been ignored. I present my opinion on possible reasons and hurdles for slower progress in understanding human behavior, briefly present our work in tracking, representation, and recognition, and comment on the next steps in all three areas.Published online: 28 August 2003