Berk Gökberk

Bosphorus Database for 3D Face Analysis

A new 3D face database that includes a rich set of expressions, systematic variation of poses and different types of occlusions is presented in this paper. This database is unique from three aspects: i) the facial expressions are composed of judiciously selected subset of Action Units as well as the six basic emotions, and many actors/actresses are incorporated to obtain more realistic expression data; ii) a rich set of head pose variations are available; and iii) different types of face occlusions are included. Hence, this new database can be a very valuable resource for development and evaluation of algorithms on face recognition under adverse conditions and facial expression analysis as well as for facial expression synthesis.

3D shape-based face recognition using automatically registered facial surfaces

We address the use of three-dimensional facial shape information for human face identification. We propose a new method to represent faces as 3D registered point clouds. Fine registration of facial surfaces is done by first automatically finding important facial landmarks and then, establishing a dense correspondence between points on the facial surface with the help of a 3D face template-aided thin plate spline algorithm. After the registration of facial surfaces, similarity between two faces is defined as a discrete approximation of the volume difference between facial surfaces. Experiments done on the 3D RMA dataset show that the proposed algorithm performs as good as the point signature method, and it is statistically superior to the point distribution model-based method and the 2D depth imagery technique. In terms of computational complexity, the proposed algorithm is faster than the point signature method.

3D shape-based face representation and feature extraction for face recognition

Abstract In this paper, we review and compare 3D face registration and recognition algorithms, which are based solely on 3D shape information and analyze methods based on the fusion of shape features. We have analyzed two different registration algorithms, which produce a dense correspondence between faces. The first algorithm non-linearly warps faces to obtain registration, while the second algorithm allows only rigid transformations. Registration is handled with the use of an average face model, which significantly fastens the registration process. As 3D facial features, we compare the use of 3D point coordinates, surface normals, curvature-based descriptors, 2D depth images, and facial profile curves. Except for surface normals, these feature descriptors are frequently used in state-of-the-art 3D face recognizers. We also perform an in-depth analysis of decision-level fusion techniques such as fixed-rules, voting schemes, rank-based combination rules, and novel serial fusion architectures. The results of the recognition and authentication experiments conducted on the 3D_RMA database indicate that: (i) in terms of face registration method, registration of faces without warping preserves more discriminatory information, (ii) in terms of 3D facial features, surface normals attain the best recognition performance, and (iii) fusion schemes such as product rules, improved consensus voting and proposed serial fusion schemes improve the classification accuracy. Experimental results on the 3D_RMA confirm these findings by obtaining %0.1 misclassification rate in recognition experiments, and %8.06 equal error rate in authentication experiments using surface normal-based features. It is also possible to improve the classification accuracy by %2.38 using fixed fusion rules when moderate-level classifiers are used.

A 3D Face Recognition System for Expression and Occlusion Invariance

Facial expression variations and occlusions complicate the task of identifying persons from their 3D facial scans. We propose a new 3D face registration and recognition method based on local facial regions that is able to provide better accuracy in the presence of expression variations and facial occlusions. Proposed fast and flexible alignment method uses average regional models (ARMs), where local correspondences are inferred by the iterative closest point (ICP) algorithm. Dissimilarity scores obtained from local regional matchers are fused to robustly identify probe subjects. In this work, a multi-expression 3D face database, Bosphorus 3D face database, that contains significant amount of different expression types and realistic facial occlusion is used for identification experiments. The experimental results on this challenging database demonstrate that the proposed system improves the performance of the standard ICP-based holistic approach (71.39%) by obtaining 95.87% identification rate in the case of expression variations. When facial occlusions are present, the performance gain is even better. Identification rate improves from 47.05% to 94.12%.

Fingerprint Verification Using Spectral Minutiae Representations

Most fingerprint recognition systems are based on the use of a minutiae set, which is an unordered collection of minutiae locations and orientations suffering from various deformations such as translation, rotation, and scaling. The spectral minutiae representation introduced in this paper is a novel method to represent a minutiae set as a fixed-length feature vector, which is invariant to translation, and in which rotation and scaling become translations, so that they can be easily compensated for. These characteristics enable the combination of fingerprint recognition systems with template protection schemes that require a fixed-length feature vector. This paper introduces the concept of algorithms for two representation methods: the location-based spectral minutiae representation and the orientation-based spectral minutiae representation. Both algorithms are evaluated using two correlation-based spectral minutiae matching algorithms. We present the performance of our algorithms on three fingerprint databases. We also show how the performance can be improved by using a fusion scheme and singular points.

Rank-based decision fusion for 3D shape-based face recognition

In 3D face recognition systems, 3D facial shape information plays an important role. Various shape representations have been proposed in the literature. The most popular techniques are based on point clouds, surface normals, facial profiles, and statistical analysis of depth images. The contribution of the presented work can be divided into two parts: In the first part, we have developed face classifiers which use these popular techniques. A comprehensive comparison of these representation methods are given using 3D RMA dataset. Experimental results show that the linear discriminant analysis-based representation of depth images and point cloud representation perform best. In the second part of the paper, two different multiple-classifier architectures are developed to fuse individual shape-based face recognizers in parallel and hierarchical fashions at the decision level. It is shown that a significant performance improvement is possible when using rank-based decision fusion in ensemble methods.

Representation Plurality and Fusion for 3-D Face Recognition

In this paper, we present an extensive study of 3D face recognition algorithms and examine the benefits of various score-, rank-, and decision-level fusion rules. We investigate face recognizers from two perspectives: the data representation techniques used and the feature extraction algorithms that match best each representation type. We also consider novel applications of various feature extraction techniques such as discrete Fourier transform, discrete cosine transform, nonnegative matrix factorization, and principal curvature directions to the shape modality. We discuss and compare various classifier combination methods such as fixed rules and voting- and rank-based fusion schemes. We also present a dynamic confidence estimation algorithm to boost fusion performance. In identification experiments performed on FRGC v1.0 and FRGC v2.0 face databases, we have tried to find the answers to the following questions: 1) the relative importance of the face representation techniques vis-a-vis the types of features extracted; 2) the impact of the gallery size; 3) the conditions, under which subspace methods are preferable, and the compression factor; 4) the most advantageous fusion level and fusion methods; 5) the role of confidence votes in improving fusion and the style of selecting experts in the fusion; and 6) the consistency of the conclusions across different databases.

3D Face Recognition Benchmarks on the Bosphorus Database with Focus on Facial Expressions

This paper presents an evaluation of several 3D face recognizers on the Bosphorus database which was gathered for studies on expression and pose invariant face analysis. We provide identification results of three 3D face recognition algorithms, namely generic face template based ICP approach, one-to-all ICP approach, and depth image-based Principal Component Analysis (PCA) method. All of these techniques treat faces globally and are usually accepted as baseline approaches. In addition, 2D texture classifiers are also incorporated in a fusion setting. Experimental results reveal that even though global shape classifiers achieve almost perfect identification in neutral-to-neutral comparisons, they are sub-optimal under extreme expression variations. We show that it is possible to boost the identification accuracy by focusing on the rigid facial regions and by fusing complementary information coming from shape and texture modalities.

3D Face: biometric template protection for 3d face recognition

In this paper we apply template protection to an authentication system based on 3D face data in order to protect the privacy of its users. We use the template protection system based on the helper data system (HDS). The experimental results performed on the FRGC v2.0 database demonstrate that the performance of the protected system is of the same order as the performance of the unprotected system. The protected system has a performance of a FAR ≈ 0.19% and a FRR ≈ 16% with a security level of 35 bits.

Comparative Analysis of Decision-level Fusion Algorithms for 3D Face Recognition

3D shape-based face recognition algorithms can be improved by using decision-level fusion algorithms. In this work, we present a comparative analysis of various fusion algorithms, and also propose novel ones. The contributions of the paper can be summarized as: i) a through analysis of several decision-level fusion algorithms, ii) a dynamically estimated reliability-assisted fusion schemes, and iii) a novel implementation of LDA-based cascaded serial fusion algorithm. Experiments conducted on the 3D_RMA dataset confirm that serial fusion offers the best solution, and dynamic calculation of reliability estimates improves the accuracy of the standard fusion schemes