1,740 research outputs found
SELF-IMAGE MULTIMEDIA TECHNOLOGIES FOR FEEDFORWARD OBSERVATIONAL LEARNING
This dissertation investigates the development and use of self-images in augmented reality systems for learning and learning-based activities. This work focuses on self- modeling, a particular form of learning, actively employed in various settings for therapy or teaching. In particular, this work aims to develop novel multimedia systems to support the display and rendering of augmented self-images. It aims to use interactivity (via games) as a means of obtaining imagery for use in creating augmented self-images. Two multimedia systems are developed, discussed and analyzed. The proposed systems are validated in terms of their technical innovation and their clinical efficacy in delivering behavioral interventions for young children on the autism spectrum
Human recognition of basic emotions from posed and animated dynamic facial expressions
Facial expressions are crucial for social communication, especially because they make it possible to express and perceive unspoken emotional and mental states. For example, neurodevelopmental disorders with social communication deficits, such as Asperger Syndrome (AS), often involve difficulties in interpreting emotional states from the facial expressions of others.
Rather little is known of the role of dynamics in recognizing emotions from faces. Better recognition of dynamic rather than static facial expressions of six basic emotions has been reported with animated faces; however, this result hasn't been confirmed reliably with real human faces. This thesis evaluates the role of dynamics in recognizing basic expressions from animated and human faces. With human faces, the further interaction between dynamics and the effect of removing fine details by low-pass filtering (blurring) is studied in adult individuals with and without AS. The results confirmed that dynamics facilitates the recognition of emotional facial expressions. This effect, however, was apparent only with the facial animation stimuli lacking detailed static facial features and other emotional cues and with blurred human faces. Some dynamic emotional animations were recognized drastically better than static ones. With basic expressions posed by human actors, the advantage of dynamic vs. static displays increased as a function of the blur level. Participants with and without AS performed similarly in recognizing basic emotions from original non-filtered and from dynamic vs. static facial expressions, suggesting that AS involves intact recognition of simple emotional states and movement from faces. Participants with AS were affected more by the removal of fine details than participants without AS. This result supports a "weak central coherence" account suggesting that AS and other autistic spectrum disorders are characterized by general perceptual difficulties in processing global vs. local level features.Kasvonilmeet ovat tÀrkeÀ osa sosiaalista vuorovaikutusta, erityisesti koska ne tekevÀt ÀÀneen lausumattomien tunnetilojen ilmaisemisen ja havaitsemisen mahdolliseksi. Esimerkiksi sosiaalisen vuorovaikutuksen ongelmia sisÀltÀviin neurokehityksellisiin oireyhtymiin, kuten Aspergerin Syndroomaan (AS), liittyykin usein vaikeuksia kasvoilla nÀkyvien tunnetilojen tulkitsemisessa.
Liikkeen roolista tunneilmausten tunnistamisessa kasvoilta on olemassa vain vÀhÀn tietoa. On osoitettu, ettÀ dynaamiset perustunneilmaukset tunnistetaan staattisia paremmin tietokoneanimoiduilta kasvoilta, vastaavaa tulosta ei ole kuitenkaan varmennettu ihmiskasvoilla. TÀssÀ vÀitöskirjassa tutkitaan liikkeen roolia perustunneilmausten tunnistamisessa animoiduilta- ja ihmiskasvoilta. Ihmiskasvojen tapauksessa tutkitaan vuorovaikutusta liikkeen ja alipÀÀstösuodatuksen (sumennuksen) kautta tapahtuvan tarkkojen yksityiskohtien poistamisen vÀlillÀ. TÀtÀ kysymystÀ tutkitaan lisÀksi erikseen henkilöillÀ, joilla ei ole viitteitÀ AS:sta ja henkilöillÀ joilla on todettu AS. Tulokset vahvistivat, ettÀ liike edesauttaa tunneilmausten tunnistamista kasvoilta. TÀmÀ tulos oli kuitenkin havaittavissa vain kÀytetyillÀ kasvoanimaatioilla, joista puuttui kasvojen tarkkoja yksityiskohtia ja muita tunteisiin liittyviÀ vihjeitÀ sekÀ sumennetuilla ihmiskasvoilla. Jotkin dynaamiset tunneanimaatiot tunnistettiin huomattavasti staattisia paremmin. IhmisnÀyttelijöiden esittÀmien perustunneilmausten tapauksessa, liikkeen tuoma lisÀhyöty kasvoi kÀytetyn sumennustason funktiona. Osallistujat, joilla oli todettu AS, tunnistivat perustunneilmauksia yhtÀ hyvin alkuperÀisiltÀ ei-sumennetuilta kasvoilta ja dynaamisilta vs. staattisilta kasvoilta kuin muutkin osallistujat. Tulokset antavat viitteitÀ vahingoittumasta yksinkertaisten tunneilmausten ja liikkeen tunnistamisesta kasvoilta Aspergerin Syndroomassa. Osallistujat, joilla oli AS, suoriutuivat muita osallistujia heikommin, kun esitetyistÀ ÀrsykkeistÀ oli poistettu tarkkoja yksityiskohtia. TÀmÀ tulos on yhdenmukainen "heikoksi keskeiseksi koherenssiksi" nimetyn nÀkemyksen kanssa, jonka mukaan AS:aan ja muihin autismin kirjon hÀiriöihin liittyy havaitsemistason vaikeuksia yleisten vs. tarkkojen piirteiden prosessoinnissa.reviewe
Learning object behaviour models
The human visual system is capable of interpreting a remarkable variety of often subtle, learnt, characteristic behaviours. For instance we can determine the gender of a distant walking figure from their gait, interpret a facial expression as that of surprise, or identify suspicious behaviour in the movements of an individual within a car-park. Machine vision systems wishing to exploit such behavioural knowledge have been limited by the inaccuracies inherent in hand-crafted models and the absence of a unified framework for the perception of powerful behaviour models.
The research described in this thesis attempts to address these limitations, using a statistical modelling approach to provide a framework in which detailed behavioural knowledge is acquired from the observation of long image sequences. The core of the behaviour modelling framework is an optimised sample-set representation of the probability density in a behaviour space defined by a novel temporal pattern formation strategy.
This representation of behaviour is both concise and accurate and facilitates the recognition of actions or events and the assessment of behaviour typicality. The inclusion of generative capabilities is achieved via the addition of a learnt stochastic process model, thus facilitating the generation of predictions and realistic sample behaviours. Experimental results demonstrate the acquisition of behaviour models and suggest a variety of possible applications, including automated visual surveillance, object tracking, gesture recognition, and the generation of realistic object behaviours within animations, virtual worlds, and computer generated film sequences.
The utility of the behaviour modelling framework is further extended through the modelling of object interaction. Two separate approaches are presented, and a technique is developed which, using learnt models of joint behaviour together with a stochastic tracking algorithm, can be used to equip a virtual object with the ability to interact in a natural way. Experimental results demonstrate the simulation of a plausible virtual partner during interaction between a user and the machine
QUIS-CAMPI: Biometric Recognition in Surveillance Scenarios
The concerns about individuals security have justified the increasing number of surveillance
cameras deployed both in private and public spaces. However, contrary to popular belief,
these devices are in most cases used solely for recording, instead of feeding intelligent analysis
processes capable of extracting information about the observed individuals. Thus, even though
video surveillance has already proved to be essential for solving multiple crimes, obtaining relevant
details about the subjects that took part in a crime depends on the manual inspection
of recordings. As such, the current goal of the research community is the development of
automated surveillance systems capable of monitoring and identifying subjects in surveillance
scenarios. Accordingly, the main goal of this thesis is to improve the performance of biometric
recognition algorithms in data acquired from surveillance scenarios. In particular, we aim at
designing a visual surveillance system capable of acquiring biometric data at a distance (e.g.,
face, iris or gait) without requiring human intervention in the process, as well as devising biometric
recognition methods robust to the degradation factors resulting from the unconstrained
acquisition process.
Regarding the first goal, the analysis of the data acquired by typical surveillance systems
shows that large acquisition distances significantly decrease the resolution of biometric samples,
and thus their discriminability is not sufficient for recognition purposes. In the literature,
diverse works point out Pan Tilt Zoom (PTZ) cameras as the most practical way for acquiring
high-resolution imagery at a distance, particularly when using a master-slave configuration. In
the master-slave configuration, the video acquired by a typical surveillance camera is analyzed
for obtaining regions of interest (e.g., car, person) and these regions are subsequently imaged
at high-resolution by the PTZ camera. Several methods have already shown that this configuration
can be used for acquiring biometric data at a distance. Nevertheless, these methods
failed at providing effective solutions to the typical challenges of this strategy, restraining its
use in surveillance scenarios. Accordingly, this thesis proposes two methods to support the development
of a biometric data acquisition system based on the cooperation of a PTZ camera
with a typical surveillance camera. The first proposal is a camera calibration method capable
of accurately mapping the coordinates of the master camera to the pan/tilt angles of the PTZ
camera. The second proposal is a camera scheduling method for determining - in real-time -
the sequence of acquisitions that maximizes the number of different targets obtained, while
minimizing the cumulative transition time. In order to achieve the first goal of this thesis,
both methods were combined with state-of-the-art approaches of the human monitoring field
to develop a fully automated surveillance capable of acquiring biometric data at a distance and
without human cooperation, designated as QUIS-CAMPI system.
The QUIS-CAMPI system is the basis for pursuing the second goal of this thesis. The analysis
of the performance of the state-of-the-art biometric recognition approaches shows that these
approaches attain almost ideal recognition rates in unconstrained data. However, this performance
is incongruous with the recognition rates observed in surveillance scenarios. Taking into
account the drawbacks of current biometric datasets, this thesis introduces a novel dataset comprising
biometric samples (face images and gait videos) acquired by the QUIS-CAMPI system at a
distance ranging from 5 to 40 meters and without human intervention in the acquisition process.
This set allows to objectively assess the performance of state-of-the-art biometric recognition
methods in data that truly encompass the covariates of surveillance scenarios. As such, this set
was exploited for promoting the first international challenge on biometric recognition in the wild. This thesis describes the evaluation protocols adopted, along with the results obtained
by the nine methods specially designed for this competition. In addition, the data acquired by
the QUIS-CAMPI system were crucial for accomplishing the second goal of this thesis, i.e., the
development of methods robust to the covariates of surveillance scenarios. The first proposal
regards a method for detecting corrupted features in biometric signatures inferred by a redundancy
analysis algorithm. The second proposal is a caricature-based face recognition approach
capable of enhancing the recognition performance by automatically generating a caricature
from a 2D photo. The experimental evaluation of these methods shows that both approaches
contribute to improve the recognition performance in unconstrained data.A crescente preocupação com a segurança dos indivĂduos tem justificado o crescimento
do nĂșmero de cĂąmaras de vĂdeo-vigilĂąncia instaladas tanto em espaços privados como pĂșblicos.
Contudo, ao contrĂĄrio do que normalmente se pensa, estes dispositivos sĂŁo, na maior parte dos
casos, usados apenas para gravação, não estando ligados a nenhum tipo de software inteligente
capaz de inferir em tempo real informaçÔes sobre os indivĂduos observados. Assim, apesar de a
vĂdeo-vigilĂąncia ter provado ser essencial na resolução de diversos crimes, o seu uso estĂĄ ainda
confinado Ă disponibilização de vĂdeos que tĂȘm que ser manualmente inspecionados para extrair
informaçÔes relevantes dos sujeitos envolvidos no crime. Como tal, atualmente, o principal
desafio da comunidade cientĂfica Ă© o desenvolvimento de sistemas automatizados capazes de
monitorizar e identificar indivĂduos em ambientes de vĂdeo-vigilĂąncia.
Esta tese tem como principal objetivo estender a aplicabilidade dos sistemas de reconhecimento
biomĂ©trico aos ambientes de vĂdeo-vigilĂąncia. De forma mais especifica, pretende-se
1) conceber um sistema de vĂdeo-vigilĂąncia que consiga adquirir dados biomĂ©tricos a longas distĂąncias
(e.g., imagens da cara, Ăris, ou vĂdeos do tipo de passo) sem requerer a cooperação dos
indivĂduos no processo; e 2) desenvolver mĂ©todos de reconhecimento biomĂ©trico robustos aos
fatores de degradação inerentes aos dados adquiridos por este tipo de sistemas.
No que diz respeito ao primeiro objetivo, a anĂĄlise aos dados adquiridos pelos sistemas tĂpicos
de vĂdeo-vigilĂąncia mostra que, devido Ă distĂąncia de captura, os traços biomĂ©tricos amostrados
nĂŁo sĂŁo suficientemente discriminativos para garantir taxas de reconhecimento aceitĂĄveis.
Na literatura, vĂĄrios trabalhos advogam o uso de cĂąmaras Pan Tilt Zoom (PTZ) para adquirir
imagens de alta resolução à distùncia, principalmente o uso destes dispositivos no modo masterslave.
Na configuração master-slave um módulo de anålise inteligente seleciona zonas de interesse
(e.g. carros, pessoas) a partir do vĂdeo adquirido por uma cĂąmara de vĂdeo-vigilĂąncia
e a cùmara PTZ é orientada para adquirir em alta resolução as regiÔes de interesse. Diversos
métodos jå mostraram que esta configuração pode ser usada para adquirir dados biométricos
Ă distĂąncia, ainda assim estes nĂŁo foram capazes de solucionar alguns problemas relacionados
com esta estratĂ©gia, impedindo assim o seu uso em ambientes de vĂdeo-vigilĂąncia. Deste modo,
esta tese propÔe dois métodos para permitir a aquisição de dados biométricos em ambientes de
vĂdeo-vigilĂąncia usando uma cĂąmara PTZ assistida por uma cĂąmara tĂpica de vĂdeo-vigilĂąncia. O
primeiro é um método de calibração capaz de mapear de forma exata as coordenadas da cùmara
master para o Ăąngulo da cĂąmara PTZ (slave) sem o auxĂlio de outros dispositivos Ăłticos. O
segundo método determina a ordem pela qual um conjunto de sujeitos vai ser observado pela
cĂąmara PTZ. O mĂ©todo proposto consegue determinar em tempo-real a sequĂȘncia de observaçÔes
que maximiza o nĂșmero de diferentes sujeitos observados e simultaneamente minimiza o
tempo total de transição entre sujeitos. De modo a atingir o primeiro objetivo desta tese, os
dois métodos propostos foram combinados com os avanços alcançados na årea da monitorização
de humanos para assim desenvolver o primeiro sistema de vĂdeo-vigilĂąncia completamente automatizado
e capaz de adquirir dados biométricos a longas distùncias sem requerer a cooperação
dos indivĂduos no processo, designado por sistema QUIS-CAMPI.
O sistema QUIS-CAMPI representa o ponto de partida para iniciar a investigação relacionada
com o segundo objetivo desta tese. A anålise do desempenho dos métodos de reconhecimento
biométrico do estado-da-arte mostra que estes conseguem obter taxas de reconhecimento
quase perfeitas em dados adquiridos sem restriçÔes (e.g., taxas de reconhecimento
maiores do que 99% no conjunto de dados LFW). Contudo, este desempenho nĂŁo Ă© corroborado pelos resultados observados em ambientes de vĂdeo-vigilĂąncia, o que sugere que os conjuntos
de dados atuais nĂŁo contĂȘm verdadeiramente os fatores de degradação tĂpicos dos ambientes de
vĂdeo-vigilĂąncia. Tendo em conta as vulnerabilidades dos conjuntos de dados biomĂ©tricos atuais,
esta tese introduz um novo conjunto de dados biomĂ©tricos (imagens da face e vĂdeos do tipo de
passo) adquiridos pelo sistema QUIS-CAMPI a uma distùncia måxima de 40m e sem a cooperação
dos sujeitos no processo de aquisição. Este conjunto permite avaliar de forma objetiva o desempenho
dos mĂ©todos do estado-da-arte no reconhecimento de indivĂduos em imagens/vĂdeos
capturados num ambiente real de vĂdeo-vigilĂąncia. Como tal, este conjunto foi utilizado para
promover a primeira competição de reconhecimento biométrico em ambientes não controlados.
Esta tese descreve os protocolos de avaliação usados, assim como os resultados obtidos por 9
métodos especialmente desenhados para esta competição. Para além disso, os dados adquiridos
pelo sistema QUIS-CAMPI foram essenciais para o desenvolvimento de dois métodos para
aumentar a robustez aos fatores de degradação observados em ambientes de vĂdeo-vigilĂąncia. O
primeiro Ă© um mĂ©todo para detetar caracterĂsticas corruptas em assinaturas biomĂ©tricas atravĂ©s
da anĂĄlise da redundĂąncia entre subconjuntos de caracterĂsticas. O segundo Ă© um mĂ©todo de
reconhecimento facial baseado em caricaturas automaticamente geradas a partir de uma Ășnica
foto do sujeito. As experiĂȘncias realizadas mostram que ambos os mĂ©todos conseguem reduzir
as taxas de erro em dados adquiridos de forma nĂŁo controlada
You Look Familiar: How Malaysian Chinese Recognize Faces
East Asian and white Western observers employ different eye movement strategies for a variety of visual processing tasks, including face processing. Recent eye tracking studies on face recognition found that East Asians tend to integrate information holistically by focusing on the nose while white Westerners perceive faces featurally by moving between the eyes and mouth. The current study examines the eye movement strategy that Malaysian Chinese participants employ when recognizing East Asian, white Western, and African faces. Rather than adopting the Eastern or Western fixation pattern, Malaysian Chinese participants use a mixed strategy by focusing on the eyes and nose more than the mouth. The combination of Eastern and Western strategies proved advantageous in participants' ability to recognize East Asian and white Western faces, suggesting that individuals learn to use fixation patterns that are optimized for recognizing the faces with which they are more familiar
Contributions of feature shapes and surface cues to the recognition and neural representation of facial identity
A full understanding of face recognition will involve identifying the visual information that is used to discriminate different identities and how this is represented in the brain. The aim of this study was to explore the importance of shape and surface properties in the recognition and neural representation of familiar faces. We used image morphing techniques to generate hybrid faces that mixed shape properties (more specifically, second order spatial configural information as defined by feature positions in the 2D-image) from one identity and surface properties from a different identity. Behavioural responses showed that recognition and matching of these hybrid faces was primarily based on their surface properties. These behavioural findings contrasted with neural responses recorded using a block design fMRI adaptation paradigm to test the sensitivity of Haxby et al.'s (2000) core face-selective regions in the human brain to the shape or surface properties of the face. The fusiform face area (FFA) and occipital face area (OFA) showed a lower response (adaptation) to repeated images of the same face (same shape, same surface) compared to different faces (different shapes, different surfaces). From the behavioural data indicating the critical contribution of surface properties to the recognition of identity, we predicted that brain regions responsible for familiar face recognition should continue to adapt to faces that vary in shape but not surface properties, but show a release from adaptation to faces that vary in surface properties but not shape. However, we found that the FFA and OFA showed an equivalent release from adaptation to changes in both shape and surface properties. The dissociation between the neural and perceptual responses suggests that, although they may play a role in the process, these core face regions are not solely responsible for the recognition of facial identity
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