Eyewitnesses’ Visual Recollection in Suspect Identification by using Facial Appearance Model

يعتبر تمييز الوجه مجالًا نشطًا لعلوم التصوير. ومع التطورات الحديثة في تطوير رؤية الكمبيوتر ، يتم تطبيقه على نطاق واسع في مختلف المجالات ، وخاصة في فرض القانون والأمن. ان الوجه البشري مقياس حيوي يمكن استخدامه بفعالية في كل من تحديد الهوية والتحقق منها. حتى الآن ، وبغض النظر عن نموذج الوجه والمقاييس ذات الصلة المستخدمة ، فإن عيبه الرئيس هو أنه يتطلب صورة للوجه ، يتم إجراء المقارنة عليها. لذلك ، هناك حاجة دائمًا إلى أجهزة تلفزيون الدائرة المغلقة وقاعدة بيانات الوجه في نظام التشغيل. وللأسف خلال العقود القليلة الماضية ، شهدنا ظهور حرب غير متكافئة ، حيث يتم ارتكاب أعمال إرهابية في كثير من الأحيان في منطقة منعزلة بدون كاميرا مثبتة وربما بواسطة أشخاص لم يتم حفظ صورهم في أي قاعدة بيانات رسمية قبل الحدث. خلال التحقيقات اللاحقة ، كان على السلطات بالتالي الاعتماد على شهود مصابين بصدمات نفسية واحباط ، وهؤلاء تعتبر شهادتهم مشكوك فيها وغالبًا ما تكون مضللة بشأن ظهور المشتبه فيه. لمعالجة هذه المشكلة ، تقدم هذه الورقة تطبيقًا لنموذج المظهر الإحصائي للوجه الإنساني في المساعدة على تحديد هوية المشتبه به استنادًا إلى التذكر البصري للشاهد. تم تنفيذ نظام نموذج أولي عبر الإنترنت لإظهار وظائفه الأساسية. أشار كل من التقييمات المرئية والعددية الواردة هنا بشكل واضح إلى الفوائد المحتملة للنظام للغرض المقصود.Facial recognition has been an active field of imaging science. With the recent progresses in computer vision development, it is extensively applied in various areas, especially in law enforcement and security. Human face is a viable biometric that could be effectively used in both identification and verification. Thus far, regardless of a facial model and relevant metrics employed, its main shortcoming is that it requires a facial image, against which comparison is made. Therefore, closed circuit televisions and a facial database are always needed in an operational system. For the last few decades, unfortunately, we have experienced an emergence of asymmetric warfare, where acts of terrorism are often committed in secluded area with no camera installed and possibly by persons whose photos have never been kept in any official database prior to the event. During subsequent investigations, the authorities thus had to rely on traumatized and frustrated witnesses, whose testimonial accounts regarding suspect’s appearance are dubious and often misleading. To address this issue, this paper presents an application of a statistical appearance model of human face in assisting suspect identification based on witness’s visual recollection. An online prototype system was implemented to demonstrate its core functionalities. Both visual and numerical assessments reported herein evidentially indicated potential benefits of the system for the intended purpose

Face tracking and pose estimation with automatic three-dimensional model construction

A method for robustly tracking and estimating the face pose of a person using stereo vision is presented. The method is invariant to identity and does not require previous training. A face model is automatically initialised and constructed online: a fixed point distribution is superposed over the face when it is frontal to the cameras, and several appropriate points close to those locations are chosen for tracking. Using the stereo correspondence of the cameras, the three-dimensional (3D) coordinates of these points are extracted, and the 3D model is created. The 2D projections of the model points are tracked separately on the left and right images using SMAT. RANSAC and POSIT are used for 3D pose estimation. Head rotations up to ±45° are correctly estimated. The approach runs in real time. The purpose of this method is to serve as the basis of a driver monitoring system, and has been tested on sequences recorded in a moving car.Ministerio de Educación y CienciaComunidad de Madri

A Robust Face Recognition Algorithm for Real-World Applications

The proposed face recognition algorithm utilizes representation of local facial regions with the DCT. The local representation provides robustness against appearance variations in local regions caused by partial face occlusion or facial expression, whereas utilizing the frequency information provides robustness against changes in illumination. The algorithm also bypasses the facial feature localization step and formulates face alignment as an optimization problem in the classification stage

Contributions on 3D Biometric Face Recognition for point clouds in low-resolution devices

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2020.Recentemente, diversos processos de automação fazem uso de conhecimentos relacionados a visão computacional, utilizando-se das informações digitalizadas que auxiliam na tomada de decisões destes processos. O estudo de informações 3D é um assunto que vem sendo recorrente em comu- nidades de visão computacional e atividades gráficas. Uma gama de métodos vem sendo propostos visando obter melhores resultados de performance, em termos de acurácia e robustez. O objetivo deste trabalho é contribuir com métodos de reconhecimento facial em dispositivos de baixa res- olução de núvens de ponto. Neste trabalho realiza-se um processo de reconhecimento facial em uma base de dados contendo 31 sujeitos, em que cada sujeito apresenta 3 imagens de profundidade e 3 imagens de cor (RGB). As imagens de cor são utilizadas para detecção facial por uso de um Haar Cascade, que permite a extração dos pontos da face da imagem de profundidade formando uma nuvem de pontos 3D. Da nuvem de pontos foram extraídas a intensidade normal e a intensi- dade do índice de curvatura de cada ponto permitindo a formação de uma imagem bidimensional, intitulada de mapa de curvatura, a partir da qual extrai-se histogramas utilizados no processo de reconhecimento facial. Junto com os mapas de curvature, Um novo método de correspondência é proposto por meio da adaptação do algoritmo clássico de Bozorth, formando uma representação 3D de marcos faciais em nuvens de ponto de baixa resolução para prover um descritor dos pontos chaves da nuvem e extrair uma representação única de cada indivíduo. A validação é realizada e comparada com uma técnica de linha de base para reconhecimento facial 3D. O manuscrito apre- sentado provê multiplos cenários de teste (faces frontais, acurácia, escala e orientação) para ambos métodos atingindo uma acurácia de 98.92% no melhor caso dos mapas de curvature e uma acurácio de 100% no melhor caso do algoritmo clássico de Bozorth adaptado.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Recently, many automation processes make use of knowledge related to computer vision, exploiting digital information in the form of images or data that assists the decision-making of these processes. 3D data recognition is a trending topic in computer vision and graphics tasks. Many methods had been proposed for applications on 3D, expecting a better performance in accuracy and robustness. The main goal of this manuscript is to contribute with face recognition methods for low-resolution point cloud devices. In this manuscript, a face recognition process was accomplished in a 31 subject database, using colorful images (RGB) and depth images for each subject. The colorful images are utilized for face detection by a Haar Cascade algorithm, allowing the extraction of facial points in the depth image and the generation of a face 3D point cloud. The point cloud is used to extract the normal intensity and the curvature index intensity of each point, allowing the confection of a bidimensional image, entitled curvature map, of which histograms are obtained to perform the facial recognition task. Along with the curvature maps, a novel matching method is proposed by an adaptation of the classic Bozorth’s algorithm, forming a net-based 3D representation of facial landmarks in a low resolution point cloud in order to provide a descriptor of the cloud key points and extract an unique representation for each individual. The validation was fulfilled and compared with a baseline technique for 3D face recognition. The presented manuscript provide multiple testing scenarios (frontal faces, accuracy, scale and orientation) for both methods, achieving an accuracy of 98.92% in the best case of the curvature maps and an 100% accuracy in the best case of the classic Bozorth’s algorithm adaptation

Cross-Spectral Face Recognition Between Near-Infrared and Visible Light Modalities.

In this thesis, improvement of face recognition performance with the use of images from the visible (VIS) and near-infrared (NIR) spectrum is attempted. Face recognition systems can be adversely affected by scenarios which encounter a significant amount of illumination variation across images of the same subject. Cross-spectral face recognition systems using images collected across the VIS and NIR spectrum can counter the ill-effects of illumination variation by standardising both sets of images. A novel preprocessing technique is proposed, which attempts the transformation of faces across both modalities to a feature space with enhanced correlation. Direct matching across the modalities is not possible due to the inherent spectral differences between NIR and VIS face images. Compared to a VIS light source, NIR radiation has a greater penetrative depth when incident on human skin. This fact, in addition to the greater number of scattering interactions within the skin by rays from the NIR spectrum can alter the morphology of the human face enough to disable a direct match with the corresponding VIS face. Several ways to bridge the gap between NIR-VIS faces have been proposed previously. Mostly of a data-driven approach, these techniques include standardised photometric normalisation techniques and subspace projections. A generative approach driven by a true physical model has not been investigated till now. In this thesis, it is proposed that a large proportion of the scattering interactions present in the NIR spectrum can be accounted for using a model for subsurface scattering. A novel subsurface scattering inversion (SSI) algorithm is developed that implements an inversion approach based on translucent surface rendering by the computer graphics field, whereby the reversal of the first order effects of subsurface scattering is attempted. The SSI algorithm is then evaluated against several preprocessing techniques, and using various permutations of feature extraction and subspace projection algorithms. The results of this evaluation show an improvement in cross spectral face recognition performance using SSI over existing Retinex-based approaches. The top performing combination of an existing photometric normalisation technique, Sequential Chain, is seen to be the best performing with a Rank 1 recognition rate of 92. 5%. In addition, the improvement in performance using non-linear projection models shows an element of non-linearity exists in the relationship between NIR and VIS

Representations for Cognitive Vision : a Review of Appearance-Based, Spatio-Temporal, and Graph-Based Approaches

The emerging discipline of cognitive vision requires a proper representation of visual information including spatial and temporal relationships, scenes, events, semantics and context. This review article summarizes existing representational schemes in computer vision which might be useful for cognitive vision, a and discusses promising future research directions. The various approaches are categorized according to appearance-based, spatio-temporal, and graph-based representations for cognitive vision. While the representation of objects has been covered extensively in computer vision research, both from a reconstruction as well as from a recognition point of view, cognitive vision will also require new ideas how to represent scenes. We introduce new concepts for scene representations and discuss how these might be efficiently implemented in future cognitive vision systems