实时三维人脸特征点定位

为了能够自动、实时地标定三维人脸曲面上主要特征点的位置,如鼻尖点和内眼点等,提出一种实时定位三维人脸特征点的算法.首先设计了一种基于曲面划分、直方图统计的三维局部曲面描述子——球划分直方图描述子,并使用该描述子逐点提取三维曲面顶点的局部曲面信息;其次计算其相似度,以定位三维人脸曲面上的主要特征点;在采用GPU并行运算后,能够有效地对三维人脸特征点进行实时定位.在三维人脸数据库FRGC v1.0以及BU-3DFE中的实验结果表明,与其他算法相比,该算法在三维人脸曲面上具有较强的三维人脸特征点定位能力.     

三维人脸鼻子特征检测

针对现有三维数据鼻子检测与定位方法的不足,提出了自动检测与定位鼻子特征方法.通过对三维海量数据点进行二维空间Delaunay三角化并映射到三维空间,得到三维人脸模型.基于鼻子区域的凹凸特性,确定鼻子大致区域.对区域内空洞进行填补,并采用形态滤波方法对鼻子边缘进行光滑以得到准确的鼻子特征与特征点.通过对不同三维人脸数据的鼻子特征点检测与定位,表明了所提方法的有效性和可靠性.     

Gabor频率对人脸特征定位的影响研究

中心频率位于高频段的Gabor滤波器具有较小的窗口,描述图像的局部特征,满足特征点表示的独立性要求;图像的高频信息随位置的不同有显著的变化。所以,在利用Gabor小波变换系数对人脸图像的特征点进行定位时,图像的高频信息更有利于特征点的定位。本文研究了不同频率的Gabor及其组合对特征点定位的影响,通过分析和试验得到了有利于人脸特征定位的Gabor频率组合。     

面状条纹结构光在三维人脸数据获取应用研究

通过对已有的光学非接触测量技术:光纤法、双目立体视觉法、干涉法、离焦法、轴向位移转换法和三角法的优缺点进行分析,提出采用面状条纹结构光测量人脸三维数据,采用投影仪产生的结构光场投影到待测三维人脸的表面,对观察光场进行傅里叶分析、滤波和逆傅里叶变换,从变形条纹中提取出人脸的三维信息,取得了较好的试验结果.并分析了影响实验结果的因素,得出结论:面状条纹结构光测量人脸三维数据可以达到三维人脸识别的精度要求.     

基于均方根曲率和绝对曲率的三维人脸特征定位

三维面部特征的定住是三维人脸识别中的关键步骤,有效、简洁、清晰的轮廓特征是快速准确人脸识别的前提所在。本文首先简要介绍了目前主流的几种基于曲率的定位方法,然后通过进一步计算均方根曲率和绝时曲率,对于同样的图像得到了更好的特征定位效果。     

流形学习在三维人脸特征降维中的应用*

三维人脸识别是未来人脸识别的新方向,有望解决二维人脸识别的瓶颈问题;但三维人脸特征维数过高又制约了三维人脸识别的发展,特征降维意义重大。首先分析了传统降维算法的局限性和几种主要的流形学习算法,提出了将流形学习应用于三维人脸特征降维的思路,并构建了一个基于流形学习的三维人脸识别框架。     

改进的用于人脸面部特征定位的ASM方法

主动形状建模是面部特征定位和人脸识别等模式识别领域中常用的一种方法.然而,由于受到初始情况、光照等诸多因素的影响,主动形状建模经常会陷入最优化过程中的局部最小问题,从而导致其性能下降.文章在传统主动形状模型基础上,提出了一种改进的ASM算法.首先,利用Adaboost初始定位面部的显著特征区域以便在后续的搜索中进行位置的约束;其次,将原始ASM方法中的关键点的1D纹理模型改进为基于核概率密度估计模型的2D纹理模型;最后,在局部灰度模型中加入了边缘约束,使边缘信息较强的点有更大的可能成为最佳候选点.该方法可以有效地解决上述局部最小问题,并且更好地捕捉局部点的特征信息,从而更精确地进行面部特征定位.实验结果表明,改进的ASM方法在准确性和鲁棒性上有较大提高,可为后续的人脸识别打下良好的配准基础.     

基于积分投影与灰度复杂度的人脸特征定位算法

针对当前人脸特征定位的研究现状与难题,采用YCbCr椭圆聚类方法进行肤色区域提取,然后根据人脸的几何特征,通过比例、大小结构特性来判断二值化图中的目标区域是否为人脸,从而可以排除非人脸区域,再结合人脸面部器官分布特点,利用积分投影方法,对人脸区域垂直和水平两个方向分别进行灰度值累加统计,经过分析可以定位眼嘴的区域边界和中心点。同时针对积分投影的缺点,即如果头部发生倾斜会导致投影位置不准确,提出了基于灰度复杂度的眼睛定位方法,利用该方法首先定位人眼位置,然后根据人眼对人脸区域旋转校正,最后再利用积分投影定位嘴巴。     

基于特征分块的三维人脸重建和识别

针对传统三维人脸重建算法效率低且难以满足实际应用的缺陷,提出一种基于特征分块的三维人脸重建算法,并将此算法应用到三维人脸识别中,实现了基于特征分块的加权三维人脸识别。首先,利用基于平面模板的非均匀重采样法对原始数据进行归一化;其次,采用主动形状模型(ASM)算法对三维人脸和二维人脸图像进行特征定位和特征分块;然后,利用基于分块主元分析(PCA)的稀疏形变模型算法实现每个人脸分块的三维重建;最后,实现了此算法在三维人脸识别中的应用。实验表明,此重建算法具有较高的精度和重建效率,还可以达到全局最优,并且可以提高三维人脸的识别率。     

复杂背景中的人脸特征定位与提取

研究了复杂背景中的人脸特征定位与提取 ,补充和改进了已有方法 ,做了中等样本集特征定位 ,提出了用人脸的 4× 4和 5× 5镶嵌二值图求取候选脸 ,8× 8镶嵌图筛选定位人脸 ,增强滤波二值图进一步验证和提取特征 ,并结合线检测窗求取眼角位置 ,实验结果比较令人满意。     

Reshaping 3D facial scans for facial appearance modeling and 3D facial expression analysis

3D face scans have been widely used for face modeling and analysis. Due to the fact that face scans provide variable point clouds across frames, they may not capture complete facial data or miss point-to-point correspondences across various facial scans, thus causing difficulties to use such data for analysis. This paper presents an efficient approach to representing facial shapes from face scans through the reconstruction of face models based on regional information and a generic model. A new approach for 3D feature detection and a hybrid approach using two vertex mapping algorithms, displacement mapping and point-to-surface mapping, and a regional blending algorithm are proposed to reconstruct the facial surface detail. The resulting models can represent individual facial shapes consistently and adaptively, establishing facial point correspondences across individual models. The accuracy of the generated models is evaluated quantitatively. The applicability of the models is validated through the application of 3D facial expression recognition using the static 3DFE and dynamic 4DFE databases. A comparison with the state of the art has also been reported.     

多视角三维人脸识别中的特征提取

针对二维人脸识别系统在姿态发生较大变化就难以识别的问题,利用三维人脸数据姿态不变性的特征,提出了一个基于方向最大值的方法来估计鼻尖点,同时也给出姿态的角度.用子空间表示的鼻子轮廓模型被用来选择鼻尖点的最可行的候选点.另外,利用SUSAN算子提取边缘,并与方向积分投影等方法结合,快速准确的定位内外眼角点和嘴角点.实验证明该方法可以保证达到和手工自动标定特征点相差无几的准确率.     

3D/4D facial expression analysis: An advanced annotated face model approach

Facial expression analysis has interested many researchers in the past decade due to its potential applications in various fields such as human–computer interaction, psychological studies, and facial animation. Three-dimensional facial data has been proven to be insensitive to illumination condition and head pose, and has hence gathered attention in recent years. In this paper, we focus on discrete expression classification using 3D data from the human face. The paper is divided in two parts. In the first part, we present improvement to the fitting of the Annotated Face Model (AFM) so that a dense point correspondence can be found in terms of both position and semantics among static 3D face scans or frames in 3D face sequences. Then, an expression recognition framework on static 3D images is presented. It is based on a Point Distribution Model (PDM) which can be built on different features. In the second part of this article, a systematic pipeline that operates on dynamic 3D sequences (4D datasets or 3D videos) is proposed and alternative modules are investigated as a comparative study. We evaluated both 3D and 4D Facial Expression Recognition pipelines on two publicly available facial expression databases and obtained promising results.     

基于多尺度分析的三维人脸识别*

为提高人脸识别的精度,加快人脸识别的速度,提出了基于多尺度分析的三维人脸识别方法。过多的特征点容易使判别混乱,出现自相矛盾的过饱和现象,因此采用必要数和最大数的策略来限制特征点的规模。为充分利用各尺度下的人脸特征进行识别,设计了基于ICP与PCA、LDA结合的综合特征匹配方法。实验结果表明,多尺度三维人脸识别方法识别率高于各种标准识别方法,抗噪声性能突出。     

一种个性化三维人面模型及其绘制方法

设计了一种有效支持个性化变形和实时显示的三维人面模型结构,并在此基础上给出了一种特征约束的实时连续多分辨率绘制方法。模型结构的设计充分考虑了人面特征及模型中点、边、面的邻接关系,便于变形中特征点及相关区域的移动,基于此结构的特征约束的多分辨率绘制方法建立了视点参数与模型分辨率间的直接关系,在保持模型视觉特征的同时保证了实时连续绘制的实现。     

2D representation of facial surfaces for multi-pose 3D face recognition

The increasing availability of 3D facial data offers the potential to overcome the intrinsic difficulties faced by conventional face recognition using 2D images. Instead of extending 2D recognition algorithms for 3D purpose, this letter proposes a novel strategy for 3D face recognition from the perspective of representing each 3D facial surface with a 2D attribute image and taking the advantage of the advances in 2D face recognition. In our approach, each 3D facial surface is mapped homeomorphically onto a 2D lattice, where the value at each site is an attribute that represents the local 3D geometrical or textural properties on the surface, therefore invariant to pose changes. This lattice is then interpolated to generate a 2D attribute image. 3D face recognition can be achieved by applying the traditional 2D face recognition techniques to obtained attribute images. In this study, we chose the pose invariant local mean curvature calculated at each vertex on the 3D facial surface to construct the 2D attribute image and adopted the eigenface algorithm for attribute image recognition. We compared our approach to state-of-the-art 3D face recognition algorithms in the FRGC (Version 2.0), GavabDB and NPU3D database. Our results show that the proposed approach has improved the robustness to head pose variation and can produce more accurate 3D multi-pose face recognition.     

Automatic facial feature extraction and 3D face modeling using two orthogonal views with application to 3D face recognition

We present a fully automated algorithm for facial feature extraction and 3D face modeling from a pair of orthogonal frontal and profile view images of a person's face taken by calibrated cameras. The algorithm starts by automatically extracting corresponding 2D landmark facial features from both view images, then compute their 3D coordinates. Further, we estimate the coordinates of the features that are hidden in the profile view based on the visible features extracted in the two orthogonal face images. The 3D coordinates of the selected feature points obtained from the images are used first to align, then to locally deform the corresponding facial vertices of the generic 3D model. Preliminary experiments to assess the applicability of the resulted models for face recognition show encouraging results.