Precise localization of eye centers with multiple cues

Automatic detection and precise localization of human eye centers are the essential processes in photo related multimedia applications. Since eye center points are used as reference base points for further intelligent processing, precise eye center localization is very important. In face recognition the accuracy of localization of eye centers directly influences the identification accuracy. A multiple stage approach with multiple cues for detection and precise localization of eye centers is presented in this paper. Multiple scopes searching strategy is used for correctly extracting eye patch images from the background. Dedicated gradient based features and curvelet based features are constructed and used for comprehensively revealing the intensity distribution characteristics and the edge based texture around eye centers. A rebuilt score calculation mechanism is proposed and the rebuilt scores are used as a specific measurement index reflecting the matching accuracy. The final localizations of eye centers are determined with integrating the gradient based scores and curvelet based scores. The experiment results testing on public face datasets show that the localization accuracy of proposed approach outperforms the accuracy with other state of the art methods.     

CroMatcher: An ontology matching system based on automated weighted aggregation and iterative final alignment

In order to perform ontology matching with high accuracy, while at the same time retaining applicability to most diverse input ontologies, the matching process generally incorporates multiple methods. Each of these methods is aimed at a particular ontology component, such as annotations, structure, properties or instances. Adequately combining these methods is one of the greatest challenges in designing an ontology matching system. In a parallel composition of basic matchers, the ability to dynamically set the weights of the basic matchers in the final output, thus making the weights optimal for the given input, is the key breakthrough for obtaining first-rate matching performance. In this paper we present CroMatcher, an ontology matching system, introducing several novelties to the automated weight calculation process. We apply substitute values for matchers that are inapplicable for the particular case and use thresholds to eliminate low-probability alignment candidates. We compare the alignments produced by the matchers and give less weight to the matchers producing mutually similar alignments, whereas more weight is given to those matchers whose alignment is distinct and rather unique. We also present a new, iterative method for producing one-to-one final alignment of ontology structures, which is a significant enhancement of similar non-iterative methods proposed in the literature. CroMatcher has been evaluated against other state-of-the-art matching systems at the OAEI evaluation contest. In a large number of test cases it achieved the highest score, which puts it among the state-of-the-art leaders.     

Effective pattern matching of source code using abstract syntax patterns

Program understanding can be assisted by tools that match patterns in the program source. Lexical pattern matchers provide excellent performance and ease of use, but have a limited vocabulary. Syntactic matchers provide more precision, but may sacrifice performance, robustness, or power. To achieve more of the benefits of both models, we extend the pattern syntax of AWK to support matching of abstract syntax trees, as demonstrated in a tool called TAWK. Its pattern syntax is language‐independent, based on abstract tree patterns. As in AWK, patterns can have associated actions, which in TAWK are written in C for generality, familiarity, and performance. The use of C is simplified by high‐level libraries and dynamic linking. To allow processing of program files containing non‐syntactic constructs such as textual macros, mechanisms have been designed that allow matching of ‘language‐like’ macros in a syntactic fashion. We survey and apply prototypical approaches to concretely demonstrate the tradeoffs in program processing. Our results indicate that TAWK can be used to quickly and easily perform a variety of common software engineering tasks, and the extensions to accommodate non‐syntactic features significantly extend the generality of syntactic matchers. Copyright © 2005 John Wiley & Sons, Ltd.     

Scale Normalization for Isometric Shape Matching

We address the scale problem inherent to isometric shape correspondence in a combinatorial matching framework. We consider a particular setting of the general correspondence problem where one of the two shapes to be matched is an isometric (or nearly isometric) part of the other up to an arbitrary scale. We resolve the scale ambiguity by finding a coarse matching between shape extremities based on a novel scale‐invariant isometric distortion measure. The proposed algorithm also supports (partial) dense matching, that alleviates the symmetric flip problem due to initial coarse sampling. We test the performance of our matching algorithm on several shape datasets in comparison to state of the art. Our method proves useful, not only for partial matching, but also for complete matching of semantically similar hybrid shape pairs whose maximum geodesic distances may not be compatible, a case that would fail most of the conventional isometric shape matchers.     

在线融合特征的眼睛状态识别算法

针对人脸视频中眼睛定位精度影响眼睛状态识别正确率问题,提出了一种融合在线肤色模型的眼睛状态识别算法。首先,在人脸主动表观模型(AAM)定位的基础上,使用当前用户的肤色特征,建立在线肤色模型;其次,在初步定位的眼睛区域,再次使用在线肤色模型,定位内外眼角点的精确位置,并利用眼角点的位置信息提取精确的眼睛区域;最后,提取眼睛区域的局部二值特征(LBP),使用支持向量机(SVM)算法,实现对眼睛睁闭状态的鲁棒识别。实验结果表明,对比全局定位的眼角点定位算法,该算法可以进一步降低眼角点的对齐误差,在低分辨人脸中使用在线融合特征的睁闭眼状态的准确识别率分别为95.03%及95.47%,分别比直接使用Haar特征和Gabor特征的识别率提升2.9%和4.8%,在实时人脸视频中,使用在线特征可以明显提高眼睛状态识别效果。     

Matching large schemas: Approaches and evaluation

Current schema matching approaches still have to improve for large and complex Schemas. The large search space increases the likelihood for false matches as well as execution times. Further difficulties for Schema matching are posed by the high expressive power and versatility of modern schema languages, in particular user-defined types and classes, component reuse capabilities, and support for distributed schemas and namespaces. To better assist the user in matching complex schemas, we have developed a new generic schema matching tool, COMA++, providing a library of individual matchers and a flexible infrastructure to combine the matchers and refine their results. Different match strategies can be applied including a new scalable approach to identify context-dependent correspondences between schemas with shared elements and a fragment-based match approach which decomposes a large match task into smaller tasks. We conducted a comprehensive evaluation of the match strategies using large e-Business standard schemas. Besides providing helpful insights for future match implementations, the evaluation demonstrated the practicability of our system for matching large schemas.     

基于特征部位圆形域的人脸图像修复方法

针对基于样本块的纹理合成方法存在的修复结构不合理和效率较低的问题，提出基于特征部位圆形域的人脸图像修复方法。首先进行人脸特征点定位，依据特征点分布将人脸图像分割出4个特征部位圆形域，明确特征搜索域范围。然后在优先级模型中以指数函数的形式改变置信度项的衰减趋势，并结合结构梯度项使用局部梯度信息约束优先级，提高修复结果的结构连通性。在匹配块搜索阶段，根据目标块与各个特征部位圆形域的相对位置，确定匹配块的搜索域，提升搜索效率。最终在结构相似性的标准下选择结构最佳匹配块，完成结构连通的人脸图像修复。与4个先进的方法相比较，所提方法修复图像的峰值信噪比（PSNR）平均提升了1.219~2.663 dB，时间消耗平均减小了34.7%~69.6%。实验结果表明，该方法对保持人脸图像的结构连通性和视觉合理性有显著效果，在修复的精度和时间上都表现优异。     

基于证据理论的不确定模式匹配方法

由于数据源数据模式的自治性、异构性，不确定性是模式匹配过程固有的本质特性。提出了一种基于证据理论的不确定性匹配方法，首先根据属性类型把模式空间分成若干模式子空间；然后将不同的匹配器结果看作不同的证据源，利用不同的匹配器的结果生成了多个基本概率分配函数，采用改进的Dempster组合规则把多个匹配器结果自动组合，减少人工干预，并解决了不同的匹配器结果组合时证据间冲突的问题；最后利用Kuhn Munkres算法获取模式映射。实验结果表明了方法的可行性和有效性。     

Stereo error detection, correction, and evaluation

An algorithm is presented for error detection and correction of disparity, as a process separate from stereo matching, with the contention that matching is not necessarily the best way to utilize all the physical constraints characteristic to stereopsis. As a result of the bias in stereo research towards matching, vision tasks like surface interpolation and object modeling have to accept erroneous data from the stereo matchers without the benefits of any intervening stage of error correction. An algorithm which identifies all errors in disparity data that can be detected on the basis of figural continuity and corrects them is presented. The algorithm can be used as a postprocessor to any edged-based stereo matching algorithm, and can additionally be used to automatically provide quantitative evaluations on the performance of matching algorithms of this class     

Tuning the ensemble selection process of schema matchers

Schema matching is the task of providing correspondences between concepts describing the meaning of data in various heterogeneous, distributed data sources. It is recognized to be one of the basic operations required by the process of data and schema integration and its outcome serves in many tasks such as targeted content delivery and view integration. Schema matching research has been going on for more than 25 years now. An interesting research topic, that was largely left untouched involves the automatic selection of schema matchers to an ensemble, a set of schema matchers. To the best of our knowledge, none of the existing algorithmic solutions offer such a selection feature. In this paper we provide a thorough investigation of this research topic. We introduce a new heuristic, Schema Matcher Boosting (SMB). We show that SMB has the ability to choose among schema matchers and to tune their importance. As such, SMB introduces a new promise for schema matcher designers. Instead of trying to design a perfect schema matcher, a designer can instead focus on finding better than random schema matchers. For the effective utilization of SMB, we propose a complementary approach to the design of new schema matchers. We separate schema matchers into first-line and second-line matchers. First-line schema matchers were designed by-and-large as applications of existing works in other areas (e.g., machine learning and information retrieval) to schemata. Second-line schema matchers operate on the outcome of other schema matchers to improve their original outcome. SMB selects matcher pairs, where each pair contains a first-line matcher and a second-line matcher. We run a thorough set of experiments to analyze SMB ability to effectively choose schema matchers and show that SMB performs better than other, state-of-the-art ensemble matchers.     

Rank Aggregation for Automatic Schema Matching

Schema matching is a basic operation of data integration, and several tools for automating it have been proposed and evaluated in the database community. Research in this area reveals that there is no single schema matcher that is guaranteed to succeed in finding a good mapping for all possible domains and, thus, an ensemble of schema matchers should be considered. In this paper, we introduce schema metamatching, a general framework for composing an arbitrary ensemble of schema matchers and generating a list of best ranked schema mappings. Informally, schema metamatching stands for computing a "consensus" ranking of alternative mappings between two schemata, given the "individual" graded rankings provided by several schema matchers. We introduce several algorithms for this problem, varying from adaptations of some standard techniques for general quantitative rank aggregation to novel techniques specific to the problem of schema matching, and to combinations of both. We provide a formal analysis of the applicability and relative performance of these algorithms and evaluate them empirically on a set of real-world schemata     

基于改进SVR的眼睛中心定位方法

眼睛中心定位技术无法摆脱图像分辨率较低、光照条件较差、侧脸及眼睛状态不定等问题对定位精度的影响.为了解决这一问题,文中提出改进的支持向量回归(SVR)的眼睛中心定位方法,基于面部特征定位中心,同时尝试几种图像预处理技术,用于提高定位精度.实验表明,结合高斯滤波器的SVR可以获得较好的中心定位精度.     

一种由粗到精的人眼定位方法

为提高人眼定位算法的实时性和抗噪性，提出了一种基于眉眼区域内“凹陷”地形特征点检测和人眼方差滤波器的人眼定位方 法(GPL)。该方法利用Gabor小波变换和直接提取“凹陷”地形特征点技术，在眉眼区域内搜索眼睛候选点，并且利用构造的人眼方差滤波器精确定位人眼。在有噪声和无噪声的人脸图像上进行了比较仿真试验。结果表明，与纯粹基于地形特征匹配的人眼定位算法相比，GPL在定位实时性、准确性和抗噪性方面都有显著提高。     

基于视觉语义与激光点云交融构建的SLAM算法

激光雷达作为同时定位与地图构建(SLAM)传感器之一,因精度高、性能稳定等特点而被广泛研究使用.但其获得的点云数据较稀疏,包含特征信息少,会导致误匹配、位姿估计误差大等问题,影响SLAM的定位和建图精度.对此,提出一种将视觉语义信息与激光点云数据融合的SLAM算法(VSIL-SLAM).首先,基于投影思想将聚类后的点云映射到语义检测框内,生成语义物体,解决原始激光点云特征稀缺问题;然后,在形状特征的基础上引入拓扑特征对语义物体进行表述,提出基于匹配的拓扑相似性度量方法,解决单一特征造成的误匹配问题,提高匹配准确度;最后,加入语义物体点到点的几何约束,基于几何特征和语义物体构建前端里程计,并完成后端回环检测和位姿图优化设计.实验结果表明,所提出算法在定位和建图效果上都有显著提高,改善了激光SLAM算法的性能.     

基于SURF和形状上下文的人脸匹配算法

针对人脸匹配在光照、姿态、表情等背景因素影响下匹配正确率低的问题,本文提出一种基于SURF(Speeded up Robust Features)和形状上下文(Shape Context, SC)的人脸图像匹配算法。在对图像进行人脸区域检测和重构积分图预处理的基础上,本文利用两次SURF算法提取人脸特征点并匹配,第一次用SURF进行粗匹配得到初始匹配集,并据此计算待匹配人脸图像间的尺度差和角度差,以此作为约束条件第二次进行SURF精匹配,以获得更多的匹配点对,最后采用不依赖位置信息的形状上下文算法剔除误匹配点对。在IMM和Georgia人脸数据库上与目前流行的人脸匹配方法进行实验对比,实验结果显示本文算法有效增加了匹配点对数目,并提高了人脸图像匹配正确率,具有更好的稳定性和鲁棒性。     

Towards a multi-source fusion approach for eye movement-driven recognition

This paper presents a research for the use of multi-source information fusion in the field of eye movement biometrics. In the current state-of-the-art, there are different techniques developed to extract the physical and the behavioral biometric characteristics of the eye movements. In this work, we explore the effects from the multi-source fusion of the heterogeneous information extracted by different biometric algorithms under the presence of diverse visual stimuli. We propose a two-stage fusion approach with the employment of stimulus-specific and algorithm-specific weights for fusing the information from different matchers based on their identification efficacy. The experimental evaluation performed on a large database of 320 subjects reveals a considerable improvement in biometric recognition accuracy, with minimal equal error rate (EER) of 5.8%, and best case Rank-1 identification rate (Rank-1 IR) of 88.6%. It should be also emphasized that although the concept of multi-stimulus fusion is currently evaluated specifically for the eye movement biometrics, it can be adopted by other biometric modalities too, in cases when an exogenous stimulus affects the extraction of the biometric features.     

基于动态时间规整距离指纹匹配的Wi-Fi网络室内定位算法

Wi-Fi网络中常规的基于指纹匹配室内定位算法面临信号时变现象或人为干扰的影响,导致定位精度不高。为此,提出基于动态时间规整（DTW）距离相似性指纹匹配的Wi-Fi网络室内定位算法。首先,该算法将定位区域的Wi-Fi信号特征按照采样的先后顺序转化为时间序列类型指纹,通过计算Wi-Fi信号指纹动态时间规整距离的大小来获取定位点与样本点的相似性;然后,根据采样区域结构特征,将Wi-Fi信号指纹采集问题划分为三类基本的动态路径采样方式;最后,结合多种动态路径采样方式增加指纹特征信息的准确性和完整性,从而提高指纹匹配的准确性和定位精度。大量实验结果表明,较瞬时指纹匹配定位算法,所提算法误差范围在3m以内定位的累积错误率：路径区域匀速运动提高了10%,变速运动提高了13%;开放区域交叉曲线运动提高了9%,S型曲线运动提高了3%。所提算法在实际室内定位应用中能有效提高指纹匹配的准确性和定位精度。     

Mashroom+: An Interactive Data Mashup Approach with Uncertainty Handling

To integrate data on the Internet, we often have to deal with uncertainties when matching data schemas from different sources. The paper proposes an approach called Mashroom+ to support human-machine interactive data mashup, which can better handle uncertainties during the semantic matching process. To improve the correctness of matching results, an interactive matching algorithm is proposed to synthesize the matching results from multiple automatic matchers based on user feedbacks. Meanwhile, to avoid bringing too much burden on users, we utilize the entropy in information theory to measure and quantify the ambiguities of different matchers and calculate the best times for users to participate. An interactive integration environment is developed based on our approach with operator recommendation capability to support on-demand data integration. Experiments show that Mashroom+ approach can achieve good balance between high correctness of matching results and low user burden with real data.     

Personal identity verification by serial fusion of fingerprint and face matchers

The use of personal identity verification systems with multi-modal biometrics has been proposed in order to increase the performance and robustness against environmental variations and fraudulent attacks. Usually multi-modal fusion of biometrics is performed in parallel at the score-level by combining the individual matching scores. This parallel strategy exhibits some drawbacks: (i) all available biometrics are necessary to perform fusion, thus the verification time depends on the slowest system; (ii) some users could be easily recognizable using a certain biometric instead of another one and (iii) the system invasiveness increases. A system characterized by the serial combination of multiple biometrics can be a good trade-off between verification time, performance and acceptability. However, these systems have been poorly investigated, and no support for designing the processing chain has been given so far. In this paper, we propose a novel serial scheme and a simple mathematical model able to predict the performance of two serially combined matchers as function of the selected processing chain. Our model helps the designer in finding the processing chain allowing a trade-off, in particular, between performance and matching time. Experiments carried out on well-known benchmark data sets made up of face and fingerprint images support the usefulness of the proposed methodology and compare it with standard parallel fusion.