Novel approach for region merging and image segmentation for human-computer interaction

For the purpose of human-computer interaction (HCI), a vision-based gesture segmentation approach is proposed. The technique essentially includes skin color detection and gesture segmentation. The skin color detection employs a skin-color artificial neural network (ANN). To merge and segment the region of interest, we propose a novel mountain algorithm. The details of the approach and experiment results are provided. The experimental segmentation accuracy is 96.25%. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

UIDT:一种基于摄像头的用户界面模型

为了弥补WIMP界面模型对视觉交互描述的不足,提出一种基于视觉交互的用户界面模型.首先在分析和总结视觉交互过程的基础上,以活动理论为基础,提出一种以用户为中心、面向任务和基于事件驱动的用户界面模型;然后描述了该模型的组成结构及其相互关系;最后给出了一个基于此模型的视频手势交互系统实例.实验结果表明,该模型能够有效地支持视觉交互设计,使用户界面满足可用性要求.

基于视觉的手势界面关键技术研究

针对视觉手势界面存在的问题,提出了一套行之有效的解决方案.首先,为了解决视觉手势交互中的Midas Touch问题,以人类注意的信息加工模型为理论依据提出了一个可扩展的视觉手势交互模型,该模型将手势交互过程分为选择性处理、分配性处理和集中处理3个不同阶段;然后,基于该模型提出了一个视觉手势识别框架,并结合认知心理学从手势检测、跟踪和识别3个方面对该框架的各个组成模块的关键技术进行了阐述,其中手势检测模块和识别管理模块能够辅助系统在复杂的背景中滤除掉不相关信息而选择性地搜索人手并根据上下文信息对手势识别任务重定向,从而避免了系统时刻都处于激活状态并对所有的手势动作都进行识别分析,有效解决了Midas Touch问题.文中介绍了使用该方法实现的IEToolkit手势界面工具平台,并基于一个视觉手势交互系统进行了实验测试与评估,结果验证了文中方法的可用性.

基于手势的视觉用户界面研究

随着人机交互技术的发展，各种新的交互手段不断涌现，使人机交互朝着更加自然、高效和智能化的方向前进。基于手势的视觉用户界面是post-WIMP时代的一种重要的界面形式，与传统的WIMP交互方式相比视觉手势交互能够使用户摆脱鼠标键盘的束缚而采用一种更加自然、无约束的交互方式，从而提供给用户更大的交互空间、更多的交互自由度和更逼真的交互体验，具有较高的应用价值和良好的应用前景，因此被国内外越来越多的研究者所关注，迅速成为了人机交互领域一个热门的研究方向，并被广泛应用于虚拟/增强现实、普适计算、智能空间以及基于计算机的互动游戏等多个领域。 视觉交互是自然人机交互的核心和热点研究内容之一，视觉交互可以通过手势、目光、头部运动或者面部表情等多种方式进行。其中，手势是人类进行视觉交互的主要手段，手势所能表达的语义信息十分丰富。在人机交互中使用视觉手势完成交互任务不仅自然、直观和方便，而且从计算机的角度出发来看系统实现起来也较为容易。因此，基于手势的视觉用户界面得到了广泛的关注并取得了许多研究成果。从目前的研究现状来看，在基于手势的视觉用户界面研究中，仍然存在着以下的问题： （1）传统的WIMP界面模型已经不适合描述视觉手势界面这种post-WIMP界面的特点，需要对传统的用户界面模型加以扩展，构造适于描述视觉交互特征的界面模型帮助用户清晰、准确地分析和表达界面功能及其变化，描述出用户与系统的交互过程，指导软件系统的设计和实现； （2）具体的交互设计过程中还存在着许多关键技术没有解决好，例如手势的正确理解问题、算法的鲁棒性问题以及手势的可扩展性问题等； （3）传统视觉工具箱复杂难用的问题。需要降低开发难度，开发出便捷、易用、可扩展的软件界面开发工具及相应的开发方法，支持领域内非专家用户快速开发出视觉手势原型系统。 本文正是从以上问题出发，围绕着视觉手势界面交互技术，从理论、方法与应用等几个方面展开了深入的研究。首先论述了用户界面的发展历程，继而对视觉界面研究现状进行了综述。在充分研究和对比国内外相关研究成果的基础上提出了一种基于手势的视觉用户界面模型UIDT。接下来针对视觉手势交互中存在的难题，以认知心理学为理论依据提出了一种可扩展的手势交互状态转移模型，并在此基础上构建了视觉手势处理框架。随后对该框架中的关键技术进行了针对性的研究。针对非专家用户在构建具有个性化视觉手势界面过程中所遇到的问题，设计开发了一个支持视觉手势交互的开发工具IEToolkit并给出了一套基于该工具的通用的软件开发方法。最后，将上述成果应用于互动娱乐领域，取得了满意的效果。 本文的创新点主要表现在以下几个方面： 1. 提出了一种基于手势的视觉用户界面模型UIDT 在充分分析视觉交互特征的基础上，以传统的用户界面模型为基础提出了一种基于手势交互的视觉界面模型UIDT。该模型从用户模型、任务模型、设备模型和交互模型等几个方面对视觉手势交互进行了深入分析和描述，给出了各个模型的形式化定义，介绍了模型的各个组成模块以及它们之间的相互关系，讨论了视觉手势界面设计中应该遵循的设计规范。评估结果表明，该模型具有较强的通用性，有助于设计者对VBI的任务、用户、设备以及交互的不同层次进行抽象描述，使用户界面满足可用性要求，提高界面设计和原型开发的效率。 2. 提出了一个可扩展的视觉手势交互模型及一种新的视觉手势识别处理框架，围绕着该框架提出了一种新的视觉手势跟踪和识别方法 首先，提出了一个可扩展的视觉手势交互模型。根据认知心理学原理将视觉手势交互处理过程细分为选择性处理、分配性处理和集中处理三个不同的阶段，有效解决了Midas Touch问题；基于该模型提出了一个视觉手势识别框架，并结合认知心理学从手势检测、跟踪和识别三个方面对该框架的各个组成模块的关键技术进行了阐述。其中手势检测模块和识别管理模块能够辅助系统在复杂的背景中滤除掉不相关信息而选择性地搜索人手并根据上下文信息对手势识别任务重定向，从而避免了系统时刻都处于激活状态并对所有的手势动作都进行识别分析，有效解决了Midas Touch问题；为了提高系统的性能，提出了一种鲁棒的面向实时交互的变形手势跟踪方法和基于小样本学习的模板匹配方法用于动态手势识别。评估结果表明，上述技术有效地提高了系统的实时性、准确性和鲁棒性。 3. 设计开发了一个支持快速原型开发的视觉手势工具箱系统 针对目前大多数视觉手势工具箱复杂难用的问题，设计开发了一个简单、易用、可扩展的手势工具箱系统IEToolkit，实现了本文所述的各种关键交互技术。它包含了构造一个基于视觉手势的交互系统所需要的方方面面，从事件模型、交互模型、数据流模型等几个方面对工具箱的组成结构进行了描述，并给出了一个基于IEToolkit的通用的软件系统开发流程，开发人员可以将更多的精力集中在具体的高层逻辑语义处理上，而不需要过多考虑底层的技术细节与支撑结构。应用实例及评估结果表明IEToolkit能够降低开发门槛，较好地支持基于视觉手势交互的应用系统的快速构造，具有较高的应用价值。 4. 基于上述研究成果设计开发了一系列典型的视觉手势交互系统 将上述理论模型与具体的交互技术进行有效结合，在视觉手势开发工具平台基础上开发了一系列典型的互动娱乐系统，在实践中对本文的研究成果进行了有效性验证。

自主移动机器人足球比赛视觉定位方法综述

综述了RoboCup足球赛中全自主移动机器人基于视觉的定位技术,包括机器人自定位和多机器人协作物体定位.介绍了定位技术的发展情况与分类.从机器人环境构建形式的不同以及先验位姿和概率方法的应用与否等方面,系统地分析和比较了各种自定位方法.对于多机器人协作物体定位,阐述了静态方法和动态跟踪方法.总结了定位过程中需要重点研究的传感器模型构建、图像处理、特征匹配以及协作过程涉及的相关问题.最后就视觉定位存在的问题和技术发展趋势进行了讨论.

基于立体视觉的室外非结构化环境障碍物检测方法研究

随着智能机器人系统的发展，机器人的在线感知能力日益受到重视。障碍物检测能力是机器人在线感知能力的一个重要组成部分。因视觉传感器具有独特优势，基于视觉的障碍物检测方法成为目前关注的重点。 室外非结构化环境因结构复杂，机器人缺乏可有效利用的先验知识描述，导致众多障碍物检测系统在该环境中不能有效工作。本文采用全局-局部策略对场景进行由粗到精的分析，弥补室外非结构化环境先验知识不足的难题，提高机器人的在线感知能力。根据该策略，本文在基于视差图的障碍物检测系统框架中，引入视差投影图模块，提出了基于视差投影图的障碍物检测系统框架。该框架在视差投影图模块中全局分析场景视差分布水平，在立体匹配模块中局部分析场景前景目标的几何轮廓信息。依据该框架，针对实际应用中遇到的各种问题，提出了工作于室外非结构化环境的障碍物检测算法。该算法具有如下特点： 1、通过分析视差投影图的地面关联线信息，获得场景的视差分布水平。该信息一方面用来动态更改匹配算法的视差搜索范围，增强算法的实时性和鲁棒性；另一方面用来移除背景地表，简化障碍物分割过程； 2、采用双域滤波抑制噪声，获得清晰的边缘特征，降低立体匹配算法在深度不连续性区域的匹配难度； 3、借助逆向重投影的思想重采样扫描图像，在立体匹配前等效地实现了立体匹配过程中动态变更视差搜索范围的操作； 4、采用基于连通成分的扩散方法替代传统的SAD局部匹配算法，获得高质量的视差图，最终改善障碍物检测的精确性。 在室外非结构化环境中，本文对该算法进行了实验验证。通过设置不同的基线长度，验证了算法在不同的感知距离内的有效性。经实验证明，本算法在一定距离范围内能够有效的检测出障碍物。

基于视觉的水下机器人悬停定位方法与应用研究

为解决受外力扰动而影响定点作业的问题，水下机器人需要具有悬停定位(Station keeping)的功能。悬停定位是指在存在外界扰动的情况下，机器人相对于作业目标仍然能够保持期望的位置和姿态。它具有两个特点：首先，是一种动力定位，即在状态感知系统的引导下，依靠自身动力抵抗外界扰动而保持期望位姿；其二，是一种局部定位，机器人相对作业目标的空间运动范围一般不会很大。因此，对悬停定位的研究需要重点解决两个问题，一个是状态感知问题；另一个是控制问题。 传统的声学定位难以满足精度和实时性的要求，视觉是一种实现水下机器人悬停定位的重要方法。本文以国家“十五”863计划重大专项“7000米载人潜水器”的悬停定位为应用背景，从摄像机标定、特定水下目标识别、视觉伺服和演示实验四个方面进行基于视觉的水下机器人悬停定位方法与应用研究。所开发的系统采用特定观察目标作为合作目标，应用基于模型的单目位姿估计方法获取摄像机与观察目标之间的相对位姿信息，实现了悬停定位中的状态感知；然后以视觉系统提供的位姿信息为反馈,构建视觉伺服控制器，实现了水下机器人的闭环控制。 摄像机标定与水下特定目标识别是实现单目位姿估计的前提，其精度直接影响位姿估计的精度，进而影响整个悬停定位系统的性能。通常摄像机标定是一个先建立成像模型，然后求解模型参数的过程。常用的简化成像模型无法精确描述3维成像空间与2维图像平面之间的关系，并且常规标定方法存在非线性方程优化求解困难的问题。因此，本文提出一种基于虚拟摄像机的无模型标定方法。该方法把摄像机的成像过程作为一个黑盒，通过光电测量方式直接建立3维成像空间与对应2维图像平面之间的映射关系。然后根据该映射关系定义一台虚拟理想摄像机，其透视模型参数可以根据需要任意设定，而不影响最终标定结果。虚拟摄像机的引入使得本方法的应用与常规方法同样方便。实验结果表明，该标定方法可以提高位姿估计精度，特别适用于无法用数学模型精确描述成像过程的系统。 针对系统中应用的特定观察目标，设计了水下图像处理和目标识别算法。对水下图像增强处理以后，应用基于自动阈值和区域生长相结合的方法进行图像分割；然后提取观察目标的图像特征，应用基于模型的目标识别方法实现了水下目标的识别和定位。 以单目位姿估计获得的位姿信息为反馈，构建水下机器人的闭环控制器，以实现悬停定位。这是一个典型的基于位置的视觉伺服问题。针对悬停定位的特点，设计了注视优先原则，在机器人运动过程中合理规划各自由度的控制，应用专家PID控制方法实现了水下机器人视觉伺服。 应用上述研究成果，以水下机器人实验平台为载体，在室内水池搭建了演示实验系统，在国内首次完成了基于视觉的水下机器人悬停定位演示实验。实验结果表明：在悬停定位起始阶段，以观察目标在摄像机视场内为前提，机器人能够在视觉伺服控制下跟踪观察目标，并且使观察目标始终保持在摄像机视场之中；能够运动到指定位置并且保持一个特定姿态，实现了机器人的定位定姿；在受到外界扰动（外力或水流）的情况下，仍然能够恢复到原来的位姿；即使在持续水流的冲击下，也能稳定地保持期望位姿。水下机器人悬停定位演示实验为今后基于视觉的悬停定位技术应用于实际作业打下了良好基础。

交通监控系统中运动目标分类和跟踪研究

文章讲述了交通监控系统中应用视频图像流来跟踪运动目标并对目标进行分类的具体过程和原则.基于目标检测提出了双差分的目标检测算法,目标分类应用到了连续时间限制和最大可能性估计的原则,目标跟踪则结合检测到的运动目标图像和当前模板进行相关匹配.实验结果表明,该过程能够很好地探测和分类目标,去除背景信息的干扰,并能够在运动目标部分被遮挡、外观改变和运动停止等情况下连续地跟踪目标.

Research of Face Location System Based on Human Vision Simulations

In this paper we present a robust face location system based on human vision simulations to automatically locate faces in color static images. Our method is divided into four stages. In the first stage we use a gauss low-pass filter to remove the fine information of images, which is useless in the initial stage of human vision. During the second and the third stages, our technique approximately detects the image regions, which may contain faces. During the fourth stage, the existence of faces in the selected regions is verified. Having combined the advantages of Bottom-Up Feature Based Methods and Appearance-Based Methods, our algorithm performs well in various images, including those with highly complex backgrounds.

Forced Dissociation of Selectin-ligand Complexes Using Steered Molecular Dynamics Simulation

Selectin-ligand interactions are crucial to such biological processes as inflammatory cascade or tumor metastasis. How transient formation and dissociation of selectin-ligand bonds in blood flow are coupled to molecular conformation at atomic level, however, has not been well understood. In this study, steered molecular dynamics (SMD) simulations were used to elucidate the intramolecular and intermolecular conformational evolutions involved in forced dissociation of three selectin-ligand systems: the construct consisting of P-selectin lectin (Lec) and epidermal growth factor (EGF)-like domains (P-LE) interacting with synthesized sulfoglycopeptide or SGP-3, P-LE with sialyl Lewis X (sLeX), and E-LE with sLeX. SMD simulations were based on newly built-up force field parameters including carbohydrate units and sulfated tyrosine(s) using an analogy approach. The simulations demonstrated that the complex dissociation was coupled to the molecular extension. While the intramolecular unraveling in P-LESGP-3 system mainly resulted from the destroy of the two anti-parallel sheets of EGF domain and the breakage of hydrogen-bond cluster at the Lec-EGF interface, the intermolecular dissociation was mainly determined by separation of fucose (FUC) from Ca2+ ion in all three systems. Conformational changes during forced dissociations depended on pulling velocities and forces, as well as on how the force was applied. This work provides an insight into better understanding of conformational changes and adhesive functionality of selectin-ligand interactions under external forces.

Distinct Evolutionary Patterns Between Two Duplicated Color Vision Genes Within Cyprinid Fishes

We investigated the molecular evolution of duplicated color vision genes (LWS-1 and SWS2) within cyprinid fish, focusing on the most cavefish-rich genus-Sinocyclocheilus. Maximum likelihood-based codon substitution approaches were used to analyze the evolution of vision genes. We found that the duplicated color vision genes had unequal evolutionary rates, which may lead to a related function divergence. Divergence of LWS-1 was strongly influenced by positive selection causing an accelerated rate of substitution in the proportion of pocket-forming residues. The SWS2 pigment experienced divergent selection between lineages, and no positively selected site was found. A duplicate copy of LWS-1 of some cyprinine species had become a pseudogene, but all SWS2 sequences remained intact in the regions examined in the cyprinid fishes examined in this study. The pseudogenization events did not occur randomly in the two copies of LWS-1 within Sinocyclocheilus species. Some cave species of Sinocyclocheilus with numerous morphological specializations that seem to be highly adapted for caves, retain both intact copies of color vision genes in their genome. We found some novel amino acid substitutions at key sites, which might represent interesting target sites for future mutagenesis experiments. Our data add to the increasing evidence that duplicate genes experience lower selective constraints and in some cases positive selection following gene duplication. Some of these observations are unexpected and may provide insights into the effect of caves on the evolution of color vision genes in fishes.

A novel vision chip for high-speed target tracking

This paper presents a novel vision chip for high-speed target tracking. Two concise algorithms for high-speed target tracking are developed. The algorithms include some basic operations that can be used to process the real-time image information during target tracking. The vision chip is implemented that is based on the algorithms and a row-parallel architecture. A prototype chip has 64 x 64 pixels is fabricated by 0.35 pm complementary metal-oxide-semiconductor transistor (CMOS) process with 4.5 x 2.5 mm(2) area. It operates at a rate of 1000 frames per second with 10 MHz chip main clock. The experiment results demonstrate that a high-speed target can be tracked in complex static background and a high-speed target among other high-speed objects can be tracked in clean background.

Large depth-of-view portable three-dimensional laser scanner and its segmental calibration for robot vision

A portable 3D laser scanning system has been designed and built for robot vision. By tilting the charge coupled device (CCD) plane of portable 3D scanning system according to the Scheimpflug condition, the depth-of-view is successfully extended from less than 40 to 100 mm. Based on the tilted camera model, the traditional two-step camera calibration method is modified by introducing the angle factor. Meanwhile, a novel segmental calibration approach, i.e., dividing the whole work range into two parts and calibrating, respectively, with corresponding system parameters, is proposed to effectively improve the measurement accuracy of the large depth-of-view 3D laser scanner. In the process of 3D reconstruction, different calibration parameters are used to transform the 2D coordinates into 3D coordinates according to the different positions of the image in the CCD plane, and the measurement accuracy of 60 mu m is obtained experimentally. Finally, the experiment of scanning a lamina by the large depth-of-view portable 3D laser scanner used by an industrial robot IRB 4400 is also employed to demonstrate the effectiveness and high measurement accuracy of our scanning system. (C) 2007 Elsevier Ltd. All rights reserved.

Methylene blue as an indicator for sensitive electrochemical detection of adenosine based on aptamer switch

In this paper, a simple, label-free and regenerative method was proposed to study the interaction between aptamer and small molecule by using methylene blue (MB+) as an electrochemical indicator. A thiolated capture probe containing twelve bases was firstly self-assembled on gold electrode by gold-sulfur affinity. Aptamer probe containing thirty two bases, which was designed to hybridize with capture DNA sequence and specifically recognize adenosine, was then immobilized on the electrode surface by hybridization reaction. MB+ was abundantly adsorbed on the aptamer probe by the specific interaction between MB+ and guanine base in aptamer probe. MB+-anchored aptamer probe can be forced to dissociate from the sensing interface after adenosine triggered structure switching of the aptamer. The peak current of MB+ linearly decreased with the concentration of adenosine over a range of 2 x 10 (8)- x 10 (6) M with a detection limit of 1 x 10 (8) M. In addition, we examined the selectivity of this electrochemical biosensor for cytidine, uridine and guanosine that belonged to the nucleosides family and possessed 1 similar structure with adenosine.

Behavioral responses of tilapia (Oreochromis niloticus) to acute fluctuations in dissolved oxygen levels as monitored by computer vision

Behavioral and ventilatory parameters have the possibility of predicting the stress state of fish in vivo and in situ. This paper presents a new image-processing algorithm for quantifying the average swimming speed of a fish school in an aquarium. This method is based on the alteration in projected area caused by the movement of individual fish during frame sequences captured at given time intervals. The image enhancement method increases the contrast between fish and background, and is thus suitable for use in turbid aquaculture water. Behavioral parameters (swimming activity and distribution parameters) and changes in ventilation frequency (VF) of tilapia (Oreochromis niloticus) responded to acute fluctuations in dissolved oxygen (DO) which were monitored continuously in the course of normoxia, falling DO level, maintenance of hypoxia (three levels of 1.5, 0.8 and 0.3 mg l(-1)) and subsequent recovery to normoxia. These parameters responded sensitively to acute variations in DO level; they displayed significant changes (P < 0.05) during severe hypoxia (0.8 and 0.3 mg l(-1) level) compared with normoxic condition, but there was no significant difference under conditions of mild hypoxia (1.5 mg l(-1) level). There was no significant difference in VF between two levels of severe hypoxia 0.8 and 0.3 mg l(-1) level during the low DO condition. The activity and distribution parameters displayed distinguishable differences between the 0.8 and 0.3 mg l(-1) levels. The behavioral parameters are thus capable of distinguishing between different degrees of severe hypoxia, though there were relatively large fluctuations. (c) 2006 Elsevier B.V. All rights reserved.