Face recognition using SIFT features under 3D meshes

Expression, occlusion, and pose variations are three main challenges for 3D face recognition. A novel method is presented to address 3D face recognition using scale-invariant feature transform(SIFT) features on 3D meshes. After preprocessing, shape index extrema on the 3D facial surface are selected as keypoints in the difference scale space and the unstable keypoints are removed after two screening steps. Then, a local coordinate system for each keypoint is established by principal component analysis(PCA).Next, two local geometric features are extracted around each keypoint through the local coordinate system. Additionally, the features are augmented by the symmetrization according to the approximate left-right symmetry in human face. The proposed method is evaluated on the Bosphorus, BU-3DFE, and Gavab databases, respectively. Good results are achieved on these three datasets. As a result, the proposed method proves robust to facial expression variations, partial external occlusions and large pose changes.

Technologically Advanced Reusable 3D Face Shield for Health Workers Confronting COVID19

The probability of medical staff to get affected from COVID19 is much higher due to their working environment which is more exposed to infectious diseases.So,as a preventive measure the body temperature monitoring of medical staff at regular intervals is highly recommended.Infrared temperature sensing guns have proved its effectiveness and therefore such devices are used to monitor the body temperature.These devices are either used on hands or forehead.As a result,there are many issues in monitoring the temperature of frontline healthcare professionals.Firstly,these healthcare professionals keep wearing PPE(Personal Protective Equipment)kits during working hours and as a result it would be very difficult to monitor their body temperature.Secondly,these healthcare professionals also wear face shields and in such cases monitoring temperature by exposing forehead needs removal of face shield.Doing so after regular intervals is surely uncomfortable for healthcare professionals.To avoid such issues,this paper is disclosing a technologically advanced face shield equipped with sensors capable of monitoring body temperature instantly without the hassle of removing the face shield.This face shield is integrated with a built-in infrared temperature sensor.A total of 10 such face shields were printed and assembled within the university lab and then handed over to a group of ten members including faculty and students of nursing and health science department.This sequence was repeated four times and as a result 40 healthcare workers participated in the study.Thereafter,feedback analysis was conducted on questionnaire data and found a significant overall mean score of 4.59 out of 5 which indicates that the product is effective and worthy in every facet.Stress analysis is also performed in the simulated environment and found that the device can easily withstand the typically applied forces.The limitations of this product are difficulty in cleaning the product and comparatively high cost due to the deployment of electronic equipment.

Measuring 3D face deformations from RGB images of expression rehabilitation exercises

Background The accurate(quantitative)analysis of 3D face deformation is a problem of increasing interest in many applications.In particular,defining a 3D model of the face deformation into a 2D target image to capture local and asymmetric deformations remains a challenge in existing literature.A measure of such local deformations may be a relevant index for monitoring the rehabilitation exercises of patients suffering from Par-kinson’s or Alzheimer’s disease or those recovering from a stroke.Methods In this paper,a complete framework that allows the construction of a 3D morphable shape model(3DMM)of the face is presented for fitting to a target RGB image.The model has the specific characteristic of being based on localized components of deformation.The fitting transformation is performed from 3D to 2D and guided by the correspondence between landmarks detected in the target image and those manually annotated on the average 3DMM.The fitting also has the distinction of being performed in two steps to disentangle face deformations related to the identity of the target subject from those induced by facial actions.Results The method was experimentally validated using the MICC-3D dataset,which includes 11 subjects.Each subject was imaged in one neutral pose and while performing 18 facial actions that deform the face in localized and asymmetric ways.For each acquisition,3DMM was fit to an RGB frame whereby,from the apex facial action and the neutral frame,the extent of the deformation was computed.The results indicate that the proposed approach can accurately capture face deformation,even localized and asymmetric deformations.Conclusion The proposed framework demonstrated that it is possible to measure deformations of a reconstructed 3D face model to monitor facial actions performed in response to a set of targets.Interestingly,these results were obtained using only RGB targets,without the need for 3D scans captured with costly devices.This paves the way for the use of the proposed tool in remote medical rehabilitation monitoring.

基于球面调和函数的3-D人脸识别方法

根据3-D数据的优势,利用图像成像原理和球面调和函数理论,结合3-D投影原理和PCA技术建立了一个3-D人脸模型。该模型用不受光线影响的低维线性子空间的基向量来表示,将结构和纹理两个3-D信息作为整体进行考虑,使得模型只需要通过一组参数简单描述。由于本文构建的3-D模型只与人脸的内在属性有关,与光线无关,因此能够排除光线对人脸识别率的影响,本文在AR人脸数据库上的识别实验证明了本文方法的有效性。

金佛山混凝土面板堆石坝地震反应3-D分析

基于等效线性模型,采用三维非线性动力有限元法对拟建金佛山混凝土面板堆石坝进行了地震动力反应分析,重点研究了坝体在地震荷载作用下的加速度反应、动应力反应、地震永久变形的规律和分布。计算结果表明:坝顶附近加速度反应较大,应采取相应的抗震工程措施;坝体动应力反应较小;坝体残余变形不大;大坝整体抗震性能较好,满足给定地震下的抗震安全性要求。

Application of 3-D Parallel Electrical Technology Detecting the Water-Rich Areas

Coal working face is damaged more and more seriously by water below the coal face floor. Therefore, floor water detection is a must in the process of extraction. This article aims to introducing application and principle of the two-gateways parallel 3-D electrical technology and the arrangement of the observation system. The authors use this method to detect the water under the floor of a mine in north of Anhui. The results show that the two-gateways parallel 3-D electrical technology can accurately locate the water-rich areas, providing the basis for drilling drainage and grouting construction.

Analysis of Combined Radiation and Forced Convection Heat Transfer in 3D Laminar Flow over an Inclined Forward Facing Step

In the current study, a numerical investigation of three-dimensional combined convection-radiation heat transfer over an inclined forward facing step (FFS) in a horizontal rectangular duct is presented. The fluid is treated as a gray, absorbing, emitting and scattering medium. To simulate the incline surface of FFS, the blocked-off method is employed in this study. The set of governing equations for gas flow are solved numerically using the CFD technique to obtain the temperature and velocity fields. Since the gas is considered as a radiating medium, all of the convection, conduction and radiation heat transfer mechanisms are presented in the energy equation. For computation of radiative term in energy equation, the radiative transfer equation (RTE) is solved numerically by the discrete ordinates method (DOM) to find the divergence of radiative heat flux distribution inside the radiating medium. The effects of optical thickness, radiation-conduction parameter and albedo coefficient on heat transfer behavior of the system are carried out.

Synthesis,Style Editing,and Animation of 3D Cartoon Face

As a popular kind of stylized face,cartoon faces have rich application scenarios.It is challenging to create personalized 3D cartoon faces directly from 2D real photos.Besides,in order to adapt to more application scenarios,automatic style editing,and animation of cartoon faces is also a crucial problem that is urgently needed to be solved in the industry,but has not yet had a perfect solution.To solve this problem,we first propose“3D face cartoonizer”,which can generate high-quality 3D cartoon faces with texture when fed into 2D facial images.We contribute the first 3D cartoon face hybrid dataset and a new training strategy which first pretrains our network with low-quality triplets in a reconstruction-then-generation manner,and then finetunes it with high-quality triplets in an adversarial manner to fully leverage the hybrid dataset.Besides,we implement style editing for 3D cartoon faces based on k-means,which can be easily achieved without retrain the neural network.In addition,we propose a new cartoon faces'blendshape generation method,and based on this,realize the expression animation of 3D cartoon faces,enabling more practical applications.Our dataset and code will be released for future research.

面心立方3维光子晶体带隙数值研究

为了数值研究面心立方晶格球形散射体3维光子晶体能带结构,采用平面波展开方法分别计算了空气中的介质球与介质中的空气球在不同参量下的能带。结果表明,空气中的介质球不论选任何参量都不出现完全禁带,介质中的空气球在选取适当参量时能出现禁带,禁带宽度与适当空气球半径、适当基质介电常数的关系相似,禁带位置中心坐标与适当空气球半径、适当基质介电常数的关系相反。此结论推广和补充了相关文献的研究。

3D Face Similarity Measure by Frechet Distances of Geodesics

3D face similarity is a critical issue in computer vision, computer graphics and face recognition and so on. Since Fr@chet distance is an effective metric for measuring curve similarity, a novel 3D face similarity measure method based on Fr^chet distances of geodesics is proposed in this paper. In our method, the surface similarity between two 3D faces is measured by the similarity between two sets of 3D curves on them. Due to the intrinsic property of geodesics, we select geodesics as the comparison curves. Firstly, the geodesics on each 3D facial model emanating from the nose tip point are extracted in the same initial direction with equal angular increment. Secondly, the Fr@chet distances between the two sets of geodesics on the two compared facial models are computed. At last, the similarity between the two facial models is computed based on the Fr6chet distances of the geodesics obtained in the second step. We verify our method both theoretically and practically. In theory, we prove that the similarity of our method satisfies three properties： reflexivity, symmetry, and triangle inequality. And in practice, experiments are conducted on the open 3D face database GavaDB, Texas 3D Face Recognition database, and our 3D face database. After the comparison with iso-geodesic and Hausdorff distance method, the results illustrate that our method has good discrimination ability and can not only identify the facial models of the same person, but also distinguish the facial models of any two different persons.

On 3D face reconstruction via cascaded regression in shape space

Cascaded regression has been recently applied to reconstruct 3D faces from single 2D images directly in shape space, and has achieved state-of-the-art performance. We investigate thoroughly such cascaded regression based 3D face reconstruction approaches from four perspectives that are not well been studied： （1） the impact of the number of 2D landmarks; （2） the impact of the number of 3D vertices; （3） the way of using standalone automated landmark detection methods; （4） the convergence property. To answer these questions, a simplified cascaded regression based 3D face reconstruction method is devised. This can be integrated with standalone automated landmark detection methods and reconstruct 3D face shapes that have the same pose and expression as the input face images, rather than normalized pose and expression. An effective training method is also proposed by disturbing the automatically detected landmarks. Comprehensive evaluation experiments have been carried out to compare to other 3D face reconstruction methods. The results not only deepen the understanding of cascaded regression based 3D face reconstruction approaches, but also prove the effectiveness of the proposed method.

3D face recognition:A comprehensive survey in 2022

In the past ten years,research on face recognition has shifted to using 3D facial surfaces,as 3D geometric information provides more discriminative features.This comprehensive survey reviews 3D face recognition techniques developed in the past decade,both conventional methods and deep learning methods.These methods are evaluated with detailed descriptions of selected representative works.Their advantages and disadvantages are summarized in terms of accuracy,complexity,and robustness to facial variations(expression,pose,occlusion,etc.).A review of 3D face databases is also provided,and a discussion of future research challenges and directions of the topic.

三维空间深度位置上情绪面孔对返回抑制的影响

通过虚拟现实技术构建虚拟三维场景,将Posner线索化范式应用到三维空间,通过两个实验操纵了目标深度、线索有效性以及情绪面孔的效价,考察了三维空间深度位置上情绪面孔如何影响视觉空间返回抑制。结果发现,(1)情绪面孔作为目标时,目标出现在近处空间,情绪面孔效价与返回抑制存在交互作用,负性面孔下的返回抑制减小;(2)情绪面孔作为线索时,目标出现在远处空间,情绪面孔效价与返回抑制存在交互作用,负性面孔下的返回抑制增大。研究表明,三维空间中情绪面孔能够影响返回抑制的大小,且这种影响在远近空间下存在差异。

3D face recognition based on principal axes registration and fusing features

A 3D face recognition approach which uses principal axes registration(PAR)and three face representation features from the re-sampling depth image:Eigenfaces,Fisherfaces and Zernike moments is presented.The approach addresses the issue of 3D face registration instantly achieved by PAR.Because each facial feature has its own advantages,limitations and scope of use,different features will complement each other.Thus the fusing features can learn more expressive characterizations than a single feature.The support vector machine(SVM)is applied for classification.In this method,based on the complementarity between different features,weighted decision-level fusion makes the recognition system have certain fault tolerance.Experimental results show that the proposed approach achieves superior performance with the rank-1 recognition rate of 98.36%for GavabDB database.

3D Face Reconstruction Using Images from Cameras with Varying Parameters

In this paper, we present a new technique of 3D face reconstruction from a sequence of images taken with cameras having varying parameters without the need to grid. This method is based on the estimation of the projection matrices of the cameras from a symmetry property which characterizes the face, these projections matrices are used with points matching in each pair of images to determine the 3D points cloud, subsequently, 3D mesh of the face is constructed with 3D Crust algorithm. Lastly, the 2D image is projected on the 3D model to generate the texture mapping. The strong point of the proposed approach is to minimize the constraints of the calibration system： we calibrated the cameras from a symmetry property which characterizes the face, this property gives us the opportunity to know some points of 3D face in a specific well-chosen global reference, to formulate a system of linear and nonlinear equations according to these 3D points, their projection in the image plan and the elements of the projections matrix. Then to solve these equations, we use a genetic algorithm which consists of finding the global optimum without the need of the initial estimation and allows to avoid the local minima of the formulated cost function. Our study is conducted on real data to demonstrate the validity and the performance of the proposed approach in terms of robustness, simplicity, stability and convergence.

襕干裙的结构创想与三维虚拟复原

为适应数智博物馆的纺织服装文物展示,并为新中式服装品牌的结构设计注入灵感。以北京服装学院民族服饰博物馆馆藏的3款襕干裙为研究对象,首先通过图片分析、等比缩放及工艺推断获得其结构数据;然后利用AutoCAD软件绘制其结构图,并将A型裙结构理论引入到襕干裙裙幅的结构创想中以优化其腰口与下摆;最后在CLO3D软件中进行包含上下搭配与内外层次的三维虚拟复原,得到襕干裙的静态着装效果与动态展示模型。结果表明:通过控制新中式襕干裙的扇形裙幅展开圆心角可以实现其裙摆截面形态的结构平衡与摆围大小的直观可控;通过压力对比与问卷调查的综合评价,3款襕干裙的复原效果良好,为纺织服装软文物的理论研究与新中式服装工业生产建立了有效联系。

基于网格纵横局部二值模式的三维人脸识别

提出一种基于网格纵横局部二值模式的三维人脸识别方法。为了充分体现人脸表面的细节差异,有效表示出由表情引起的局部形状变化,本文首先在人脸网格表面的半刚性区域内检测关键点集,并且由关键点确定中心面片,由中心面片及其周围有序环确定关键点邻域;其次将网格上中心面片及其周围有序环看成一个整体,从纵向(相邻环上对应面片之间)和横向(同一环上相邻标号面片之间)分别提取网格纵向局部二值模式描述符和网格横向局部二值模式描述符;然后对这两者进行特征融合得到网格纵横局部二值模式描述符;最后利用LC-KSVD2字典学习算法在Bosphorus数据库和FRGC v2.0数据库上完成识别实验。在Bosphorus数据库上各表情的平均Rank-1识别率为97.6%,在FRGC v2.0数据库上的Rank-1识别率为97.9%,该实验结果充分表明本文所提算法具有较高的识别精度,并且对表情变化具有一定的鲁棒性。

基于OpenGL的三维仿真实现

提出了一种基于开放式三维图形程序标准 Ｏｐｅｎ Ｇ Ｌ 的三维仿真方法，论述了利用 Ｏｐｅｎ Ｇ Ｌ进行三维仿真的优点，以及仿真几何模型的构建、模型运动轨迹的确定、仿真过程的动态显示、以及仿真真实感实现的具体算法与策略。上述方法已成功地应用于西安飞机公司数控弯管机三维仿真软件的实现中。

基于三维人脸建模的多姿态人脸识别

待匹配人脸图像与原始图像存在姿态和光照的差异,是自动人脸识别的两个主要瓶颈问题。给出了采用三维人脸模型来解决人脸姿态的变化对人脸识别的影响问题。通过正侧面图像,利用B样条曲线与径向基函数相结合的方法进行三维人脸重建,生成三维人脸模型库。分别计算待匹配人脸图像的3个自由度,快速估计出人脸的姿态;结合待匹配人脸图像的姿态参数及三维人脸模型库,获得与待匹配图像相同姿态的三维人脸模型库中的二维人脸图像。最后完成了相同人脸姿态的二维人脸识别。实验结果证明,该方法无需复杂的设备、简单易行、识别时间短,是一种非常实用的解决人脸姿态问题的识别方法。

基于逆向工程的呼吸面罩设计

提出了利用逆向工程技术进行呼吸面罩个性化设计的方法.利用逆向工程方法获得了三维面部模型,基于人体面部的逆向造型提取出面部的特征点与特征曲线,并就典型的特征曲线进行曲面设计,完成呼吸面罩的造型设计.利用Surfacer与Pro/Engineer软件实现了特定人脸呼吸面罩的造型设计.