Estimating parameter distributions in structural reliability assessment using the Transferable Belief Model

This paper applies the Transferable Belief Model (TBM) interpretation of the Dempster-Shafer theory of evidence to estimate parameter distributions for probabilistic structural reliability assessment based on information from previous analyses, expert opinion, or qualitative assessments (i.e., evidence). Treating model parameters as credal variables, the suggested approach constructs a set of least-committed belief functions for each parameter defined on a continuous frame of real numbers that represent beliefs induced by the evidence in the credal state, discounts them based on the relevance and reliability of the supporting evidence, and combines them to obtain belief functions that represent the aggregate state of belief in the true value of each parameter. Within the TBM framework, beliefs held in the credal state can then be transformed to a pignistic state where they are represented by pignistic probability distributions. The value of this approach lies in its ability to leverage results from previous analyses to estimate distributions for use within a probabilistic reliability and risk assessment framework. The proposed methodology is demonstrated in an example problem that estimates the physical vulnerability of a notional office building to blast loading.     

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.     

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.     

基于2S-LSGCN的人体动作识别

针对视频中人体动作行为的空间复杂性和时间复杂性问题,提出一种融合图卷积神经网络和长短期记忆神经网络的双流网络方法2 S-LSGCN.从人体关节点组成的骨架关节图中,提取动作的空间与时间特征;利用GCN提取骨架关节点间潜在的空间信息,LSTM提取人体动作前后之间的时间序列特征作为补充,分别将两个网络的预测输出进行晚融合,...     

A survey on vision-based human action recognition

Vision-based human action recognition is the process of labeling image sequences with action labels. Robust solutions to this problem have applications in domains such as visual surveillance, video retrieval and human–computer interaction. The task is challenging due to variations in motion performance, recording settings and inter-personal differences. In this survey, we explicitly address these challenges. We provide a detailed overview of current advances in the field. Image representations and the subsequent classification process are discussed separately to focus on the novelties of recent research. Moreover, we discuss limitations of the state of the art and outline promising directions of research.     

Human action recognition using hull convexity defect features with multi-modality setups

We consider developing a taxonomic shape driven algorithm to solve the problem of human action recognition and develop a new feature extraction technique using hull convexity defects. To test and validate this approach, we use silhouettes of subjects performing ten actions from a commonly used video database by action recognition researchers. A morphological algorithm is used to filter noise from the silhouette. A convex hull is then created around the silhouette frame, from which convex defects will be used as the features for analysis. A complete feature consists of thirty individual values which represent the five largest convex hull defects areas. A consecutive sequence of these features form a complete action. Action frame sequences are preprocessed to separate the data into two sets based on perspective planes and bilateral symmetry. Features are then normalized to create a final set of action sequences. We then formulate and investigate three methods to classify ten actions from the database. Testing and training of the nine test subjects is performed using a leave one out methodology. Classification utilizes both PCA and minimally encoded neural networks. Performance evaluation results show that the Hull Convexity Defect Algorithm provides comparable results with less computational complexity. This research can lead to a real time performance application that can be incorporated to include distinguishing more complex actions and multiple person interaction.     

基于局部特征点方法的动作识别研究

利用局部特征点方法进行视频中的动作识别研究,通过对尺度空间理论以及多种经典的局部特征点检测方法的深入分析,将SIFT算法引入到视频研究领域,提出了一种全新而高效的视频特征点检测算法。在此基础上,设计了合理的机器学习方法对局部特征点进行训练,利用训练出的通用动作模式在视频中进行动作识别。     

Exploring trace transform for robust human action recognition

Machine based human action recognition has become very popular in the last decade. Automatic unattended surveillance systems, interactive video games, machine learning and robotics are only few of the areas that involve human action recognition. This paper examines the capability of a known transform, the so-called Trace, for human action recognition and proposes two new feature extraction methods based on the specific transform. The first method extracts Trace transforms from binarized silhouettes, representing different stages of a single action period. A final history template composed from the above transforms, represents the whole sequence containing much of the valuable spatio-temporal information contained in a human action. The second, involves Trace for the construction of a set of invariant features that represent the action sequence and can cope with variations usually appeared in video capturing. The specific method takes advantage of the natural specifications of the Trace transform, to produce noise robust features that are invariant to translation, rotation, scaling and are effective, simple and fast to create. Classification experiments performed on two well known and challenging action datasets (KTH and Weizmann) using Radial Basis Function (RBF) Kernel SVM provided very competitive results indicating the potentials of the proposed techniques.     

基于归一化R变换分层模型的人体行为识别

为保留多特征的鉴别能力和区分能力,同时不增加特征维度,提出了一种基于归一化R变换分层模型的人体行为识别方法.第一层选取描述了运动发生区域的运动能量图像(MEI)作为特征,并依据其归一化R变换曲线对行为进行大类划分;第二层利用细节特征更丰富的关键姿态的星状模型以及宽比和高比特征对各大类进行细分,实现行为的分治识别.对Weizmann和ViHaSi人体行为数据库进行实验,识别率分别为92.47％和96.67％.实验结果表明,该分层模型简单有效     

Accurate 3D action recognition using learning on the Grassmann manifold

In this paper we address the problem of modeling and analyzing human motion by focusing on 3D body skeletons. Particularly, our intent is to represent skeletal motion in a geometric and efficient way, leading to an accurate action–recognition system. Here an action is represented by a dynamical system whose observability matrix is characterized as an element of a Grassmann manifold. To formulate our learning algorithm, we propose two distinct ideas: (1) in the first one we perform classification using a Truncated Wrapped Gaussian model, one for each class in its own tangent space. (2) In the second one we propose a novel learning algorithm that uses a vector representation formed by concatenating local coordinates in tangent spaces associated with different classes and training a linear SVM. We evaluate our approaches on three public 3D action datasets: MSR-action 3D, UT-kinect and UCF-kinect datasets; these datasets represent different kinds of challenges and together help provide an exhaustive evaluation. The results show that our approaches either match or exceed state-of-the-art performance reaching 91.21% on MSR-action 3D, 97.91% on UCF-kinect, and 88.5% on UT-kinect. Finally, we evaluate the latency, i.e. the ability to recognize an action before its termination, of our approach and demonstrate improvements relative to other published approaches.     

Discriminative human action recognition in the learned hierarchical manifold space

In this paper, we propose a hierarchical discriminative approach for human action recognition. It consists of feature extraction with mutual motion pattern analysis and discriminative action modeling in the hierarchical manifold space. Hierarchical Gaussian Process Latent Variable Model (HGPLVM) is employed to learn the hierarchical manifold space in which motion patterns are extracted. A cascade CRF is also presented to estimate the motion patterns in the corresponding manifold subspace, and the trained SVM classifier predicts the action label for the current observation. Using motion capture data, we test our method and evaluate how body parts make effect on human action recognition. The results on our test set of synthetic images are also presented to demonstrate the robustness.     

Human action recognition based on quaternion spatial-temporal convolutional neural network and LSTM in RGB videos

Multimedia Tools and Applications - Convolutional neural networks (CNN) are the state-of-the-art method for action recognition in various kinds of datasets. However, most existing CNN models are...     

基于区分性Model Pushing的语种识别方法

提出一种区分性Model Pushing方法,将SVM训练出的支持向量沿最优分类面的法线方向进行适当移动,增大不同语种间的区分性,然后将移动后的支持向量反向应用于GMM.该方法既保留了SVM的区分性信息,又利用了GMM在短时语音上的优势,同时增加了目标与非目标的区分度.实验结果表明,区分性Model Pushing能有效地提高识别性能.     

基于OpenCV的摄像头动态手势轨迹识别及其应用

利用OpenCV计算机视觉库在vs2008平台上设计了一个基于实时摄像头的集动态手势检测、动态手势跟踪、动态手势轨迹识别的应用.首先,该应用基于静止的背景更新,利用背景差分检测运动手势,再结合颜色直方图的粒子滤波进行动态手势跟踪,最后利用隐马尔可夫模型(HMM)进行运动轨迹识别.在运动检测部分结合了背景差分图与通过颜色直方图获得的反投影图,达到比较满意的实时运动检测效果;在运动手势跟踪部分,改进的颜色直方图的粒子跟踪能够在经过类肤色人脸的干扰后迅速地找回运动手势,基本达到了跟踪的要求,但是同时对于HMM识别轨迹时需要的运动轨迹序列采集造成了影响;在识别轨迹部分,HMM的训练达到了识别的要求,但是识别的效果主要取决于实时运动轨迹序列的采集工作与采集方法的优化.     

基于贝叶斯网络的步态识别

步态作为一种重要的生物特征由于其远距离身份识别能力而逐渐受到人们的重视。本文提出了一种基于贝叶斯网络的步态识别方法。首先应用背景差方法获得运动人体侧面二值图像,将侧面像分为七部分来提取特征,采用最大方差法对训练集进行离散化,对各部分分别建立贝叶斯网络,最后利用“投票”规则将网络推理结果进行组合。将该方法在Soton步态数据库上进行试验,取得了比较理想的识别效果。     

Contour graph based human tracking and action sequence recognition

This paper introduces a new framework for human contour tracking and action sequence recognition. Given a gallery of labeled human contour sequences, we define each contour as a “word” and encode all of them into a contour dictionary. This dictionary will be used to translate the video. To this end, a contour graph is constructed by connecting all the neighboring contours. Then, the motion in a video is viewed as an instance of random walks on this graph. As a result, we can avoid explicitly parameterizing the contour curves and modeling the dynamical system for contour updating. In such a work setting, there are only a few state variables to be estimated when using sequence Monte Carlo (SMC) approach to realize the random walks. In addition, the walks on the graph also perform sequence comparisons implicitly with those in the predefined gallery, from which statistics about class label is evaluated for action recognition. Experiments on diving tracking and recognition illustrate the validity of our method.     

Multiple scale-specific representations for improved human action recognition

Human action recognition in video is important in many computer vision applications such as automated surveillance. Human actions can be compactly encoded using a sparse set of local spatio-temporal salient features at different scales. The existing bottom-up methods construct a single dictionary of action primitives from the joint features of all scales and hence, a single action representation. This representation cannot fully exploit the complementary characteristics of the motions across different scales. To address this problem, we introduce the concept of learning multiple dictionaries of action primitives at different resolutions and consequently, multiple scale-specific representations for a given video sample. Using a decoupled fusion of multiple representations, we improved the human classification accuracy of realistic benchmark databases by about 5%$5\%$, compared with the state-of-the art methods.