基于自适应活动轮廓模型的实时手势跟踪

在基于视觉的手势分析与识别中,一个关键环节是手势跟踪。本文提出了基于颜色信息的自适应活动轮廓模型,并与均值漂移算法相互融合,实现图像序列的实时手势跟踪。跟踪算法分为两步进行,首先应用均值漂移算法实现手部区域的定位,然后基于自适应活动轮廓模型提取手部轮廓。在跟踪过程中,轮廓提取为下一帧的区域定位更新搜索窗口,提高了搜索效率,使目标跟踪达到实时性要求。同时,本文根据跟踪区域模板与目标模板的相似性度量Bhattacaryya系数给出了在跟踪目标被遮挡时的处理方法,有效地解决了这一难题。实验结果证明了在无遮挡和遮挡两种情况下算法均能实现准确、实时的手势跟踪。     

基于形状特征检测的手势感兴趣区提取方法

针对采用肤色模型法进行手部区域分割时,人穿着的服装对手臂区域的干扰问题,本文提出了通过手部形状特征检测的手势感兴趣区提取方法.首先利用YCb'Cr’肤色模型提取手部轮廓,通过基于轮廓凸壳信息的方法提取手部轮廓区域的最小外接矩形;然后结合手掌和手臂的特有形状特征识别手腕位置,准确提取出手势感兴趣区域.实验结果表明,本文方法检测手部感兴趣区域准确,对包含和不含手臂的图像中手势感兴趣区域提取均有明显效果.     

基于范例集实现复杂场景下的动态手势跟踪

范例集作为近年来视觉跟踪器的一种表示方法,已应用于手势跟踪与识别。但是基于范例集的手势跟踪往往不能实现复杂场景下手部轮廓特征的精确提取,并且不能在手部位置与方向任意变化情况下实现手部轮廓的提取与跟踪,极易造成手部动作的不准确预测,从而影响手势跟踪效果与手势识别率。本文提出一种新的基于范例集的跟踪器：CEE(CAMSHIFT Embedded Exemplar)跟踪器,实现复杂场景下的动态手势跟踪。在学习阶段,利用ICAMSHIFT（Improved CAMSHIFT）算法提取手部轮廓特征并生成范例集,同时建立手势的动态HMM模型;在跟踪阶段,首先利用由ICAMSHIFT算法获取的手部特征和HMM概率模型预测手势动作,然后根据学习所得范例集获取当前手部轮廓。实验结果表明,算法能实现复杂场景下的准确手势跟踪,并能在手部位置与方向任意变化情况下实现手部轮廓的提取与跟踪。此外,在严重遮挡情况下也能取得不错的跟踪效果。     

融合GVF Snake与肤色模型的手势轮廓提取方法

针对在基于视觉的手势识别系统中手势轮廓难以准确提取问题,本文提出一种融合GVF Snake和肤色模型的手势轮廓提取方法.首先把图像由RGB空间转换到YCb'Cr’空间,利用该空间上的椭圆肤色模型检测出手势区域并提取手势轮廓作为GVF Snake模型的初始轮廓曲线;然后根据图像分块思想把检测出的手势所在图像区域分割出来,并计算该图像分块的梯度值;最后在图像分块和初始轮廓曲线的基础上通过GVF Snake模型迭代搜素准确提取手势轮廓.实验结果表明,本文提出的手势轮廓提取方法无需人工参与,准确性上优于肤色模型、传统Snake模型,实时性上优于GVF Snake模型,满足手势识别系统中手势轮廓提取的实时性和准确性要求.检测准确、实时性高.     

视频图像序列运动目标检测及轮廓提取

考虑到人类视觉对图像轮廓特征的敏感性,将目标检测与轮廓提取结合起来,实现了目标轮廓自动提取的方法.首先采用了背景差法跟踪视频图像序列中的运动目标,并采用了自适应背景更新的方法更新背景图像,结合活动轮廓模型法GVF Snake进行目标轮廓的提取,从而得到具有精确边界的运动目标.实验结果表明这种方法运算速度快、能够快速地收敛到目标轮廓、准确地跟踪目标,实现实时自动轮廓跟踪.     

基于改进射线矢量法的手部轮廓与手势实时跟踪方法

目前,在视频分析和处理过程中,运动物体的实时检测和与轮廓跟踪作为计算机视觉分析识别的基础,已变得越来越重要了.改进了传统的射线矢量法表示物体形状的方法,并结合拆分法和聚合法对单帧图像进行分割,以得到完整而准确的手部曲线,在相邻帧之间采用了Kalman滤波器估计帧间手部运动的轨迹来实现跟踪过程.该方法很好地克服了传统射线矢量法所无法表示的形状的缺陷,能够准确地跟踪手部的运动以及各种手势.     

基于CamShift和Kalman滤波混合的视频手势跟踪算法*

提出了一种基于CamShift和Kalman滤波混合的跟踪算法,实现了对视频图像中动态手势的跟踪。在跟踪过程中,CamShift利用手势的颜色直方图模型,将图像序列通过一个肤色概率查找表转换为肤色概率分布图,结合运动信息和肤色概率分布,初始化一个搜索窗的大小和位置,并根据上一帧跟踪的结果自适应调整搜索窗口的位置和大小,从而定位出当前图像中手势的中心位置。在CamShift算法基础上利用Kalman滤波对搜索窗口进行运动预测。实验表明,该算法快速准确可靠,并且较好地处理了跟踪过程中大面积肤色干扰问题,对复杂     

基于统计模型的遗传粒子滤波器人体运动跟踪*

提出了一种基于统计模型的遗传粒子滤波器人体运动跟踪算法。引入局域二值模式(LBP)算子提取纹理特征,利用颜色直方图与纹理直方图相似度的加权和表示目标相似度,以有效解决自遮挡对跟踪的影响。利用该统计模型精确表示运动人体轮廓,目标形状可由一可变形状参数确定;采用遗传粒子滤波器作为跟踪算法以提高粒子滤波器的鲁棒性和精度。通过预测更新可变形状参数,再利用统计模型中目标形状与形状可变参数的关系得到图像序列各帧中人体轮廓,有效降低了计算量,从而达到快速而准确的跟踪目的。最后用上述方法进行了实验,验证了该方法的实用性和有效性。     

基于马尔可夫模型的手势识别算法

同时应用手形及其运动轨迹两大特征实现动态手势识别。在轮廓跟踪过程中,获得手部轮廓,同时用轮廓质心的坐标表示手的位置获取手势的运动轨迹,则可得动态手势的特征向量,即观察值序列;然后采用左右结构的带有4个状态的离散马尔可夫模型实现手势识别。试验结果表明算法提高了手势识别率,也达到了实时性效果。     

图像识别的静态手势识别与动态跟踪系统设计

本文研究了图像手势识别和增强现实技术,设计了可以进行静态手势识别和动态跟踪的系统,通过提前录入不同手势,利用皮肤颜色对图像进行OSTU自适应阈值划分,建立二值化图像,与已知的手势进行匹配,以得到手势结果。实验结果表明,准确率达到96.8%,识别速度达到0.55 s。动态跟踪利用检测每帧图像中手部的位置进行定位和捕捉,图像捕捉帧数达到28帧/s,对手势静态识别和动态跟踪实现了人机之间的良好交互。     

Nonstationary color tracking for vision-based human-computer interaction

Skin color offers a strong cue for efficient localization and tracking of human body parts in video sequences for vision-based human-computer interaction. Color-based target localization could be achieved by analyzing segmented skin color regions. However, one of the challenges of color-based target tracking is that color distributions would change in different lighting conditions such that fixed color models would be inadequate to capture nonstationary color distributions over time. Meanwhile, using a fixed skin color model trained by the data of a specific person would probably not work well for other people. Although some work has been done on adaptive color models, this problem still needs further studies. We present our investigation of color-based image segmentation and nonstationary color-based target tracking, by studying two different representations for color distributions. We propose the structure adaptive self-organizing map (SASOM) neural network that serves as a new color model. Our experiments show that such a representation is powerful for efficient image segmentation. Then, we formulate the nonstationary color tracking problem as a model transduction problem, the solution of which offers a way to adapt and transduce color classifiers in nonstationary color distributions. To fulfill model transduction, we propose two algorithms, the SASOM transduction and the discriminant expectation-maximization (EM), based on the SASOM color model and the Gaussian mixture color model, respectively. Our extensive experiments on the task of real-time face/hand localization show that these two algorithms can successfully handle some difficulties in nonstationary color tracking. We also implemented a real-time face/hand localization system based on such algorithms for vision-based human-computer interaction.     

自适应融合颜色和深度信息的人体轮廓跟踪

采用活动轮廓对人体目标建模,提出一 种新的水平集框架下自适应融合RGB-D图像的颜色和深度信息的人体轮廓跟踪方法. 设计了一种基于超像素的局部自适应权重计算方法,自动确定深度信息在水平集演化中的重要性. 基于深度信息的活动轮廓驱动外力包括由边缘生成的梯度向量流和由目标/背景深度模型生成的置信图,基于颜色信息的驱动外力由目标/背景颜色模型生成的置信图,这三种外力通过局部自适应权重融合,驱动活动轮廓向目标的边界演化.为了得到更加精确的目标轮廓和防止误差漂移,基于本文观察到的人体表面在深度图像中的两个特性,提出两个简单但有效的算法对水平集方法得到的结果进行精化调整. 最后,通过实验验证了本文算法的优越性.     

应用Snake模型提取彩色图象目标轮廓线的研究

为了更好地利用Snake模型来提取彩色图象中的物体轮廓，因而对Snake原型提出两点主要改进，即针对snake模型的手工初值设置问题，通过引入彩色聚类预处理过程来减少对人的依赖，首先，采用色彩聚类算法对原始图象进行分割，然后用改进的边缘追踪算法提取有意义区域的边缘，并用这一结果作为Snake模型的初值；然后针对Snake原型应用于彩色图象时出现的失真问题，通过对出错原因的分析，重新设计了Snake的外部能量函数，同时用像素在加权HSI颜色空间中的欧氏距离代替传统方法中常用的像素灰度的差分来近似图象梯度；最后，进行了对比实验，实验结果证明，改进后的算法，特别是在处理彩色图象时，大大优于原始方法．     

Online adaptive radial basis function networks for robust object tracking

Visual tracking has been a challenging problem in computer vision over the decades. The applications of visual tracking are far-reaching, ranging from surveillance and monitoring to smart rooms. In this paper, we present a novel online adaptive object tracker based on fast learning radial basis function (RBF) networks. Pixel based color features are used for developing the target/object model. Here, two separate RBF networks are used, one of which is trained to maximize the classification accuracy of object pixels, while the other is trained for non-object pixels. The target is modeled using the posterior probability of object and non-object classes. Object localization is achieved by iteratively seeking the mode of the posterior probability of the pixels in each of the subsequent frames. An adaptive learning procedure is presented to update the object model in order to tackle object appearance and illumination changes. The superior performance of the proposed tracker is illustrated with many complex video sequences, as compared against the popular color-based mean-shift tracker. The proposed tracker is suitable for real-time object tracking due to its low computational complexity.     

A local-motion-based probabilistic model for visual tracking

Color-based tracking is prone to failure in situations where visually similar targets are moving in a close proximity or occlude each other. To deal with the ambiguities in the visual information, we propose an additional color-independent visual model based on the target's local motion. This model is calculated from the optical flow induced by the target in consecutive images. By modifying a color-based particle filter to account for the target's local motion, the combined color/local-motion-based tracker is constructed. We compare the combined tracker to a purely color-based tracker on a challenging dataset from hand tracking, surveillance and sports. The experiments show that the proposed local-motion model largely resolves situations when the target is occluded by, or moves in front of, a visually similar object.     

Adaptive skin color modeling using the skin locus for selecting training pixels

Techniques for color-based tracking of faces or hands often assume a static skin model yet skin color, as measured by a camera, can change when lighting changes. Therefore, for robust skin pixel detection, an adaptive skin color model must be employed. We demonstrate a chromaticity-based constraint to select training pixels in a scene for updating a dynamic skin color model under changing illumination conditions. The method makes use of the ‘skin locus’ of a camera, that is, the area in chromaticity space where skin chromaticity under various lighting and camera calibration conditions is observed. Skin color models derived from the technique are compared with that derived by a common spatial constraint and is shown to be more consistent with manually extracted ground truth skin model per frame even as localization errors increase. The technique is applied to color-based face tracking in indoor and outdoor videos and is shown to succeed more often than other color model adaptation techniques.     

基于Snake模型的植物叶片面积计算方法

为对植物叶片面积进行准确测量,提出一种通过Snake模型提取叶片轮廓,并在叶片轮廓基础上计算面积的方法。对传统Snake模型进行改进,定义HSI空间的颜色梯度作为Snake的外部能量函数,将提取出的角点作为初始轮廓的顶点,通过自适应增加或减少顶点来设置Snake的初值。利用改进的Snake模型提取叶片轮廓,在叶片轮廓链码表的基础上计算面积。实验结果表明,与Image J软件中计算叶片面积的方法相比,该算法的测量精度更高。     

基于粒子滤波与改进水平集的人手跟踪

提出一种基于肤色信息的改进水平集分割算法,给出整个算法的推导和实现过程,实现复杂背景下的精确人手轮廓分割,在进行人手跟踪时,使用粒子滤波对手的位置和大小进行跟踪,并用跟踪结果初始化水平集函数,以此加快轮廓曲线的收敛速度,获得手的轮廓后,对指尖位置进行定位。实验结果表明,该算法能够在复杂背景下实时、准确地跟踪人手轮廓和指尖位置。