Spatio-temporal centroid based sign language facial expressions for animation synthesis in virtual environment

Orientador: Eduardo TodtTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa : Curitiba, 20/02/2019Inclui referências: p.86-97Área de concentração: Ciência da ComputaçãoResumo: Formalmente reconhecida como segunda lingua oficial brasileira, a BSL, ou Libras, conta hoje com muitas aplicacoes computacionais que integram a comunidade surda nas atividades cotidianas, oferecendo interpretes virtuais representados por avatares 3D construidos utilizando modelos formais que parametrizam as caracteristicas especificas das linguas de sinais. Estas aplicacoes, contudo, ainda consideram expressoes faciais como recurso de segundo plano em uma lingua primariamente gestual, ignorando a importancia que expressoes faciais e emocoes imprimem no contexto da mensagem transmitida. Neste trabalho, a fim de definir um modelo facial parametrizado para uso em linguas de sinais, um sistema de sintese de expressoes faciais atraves de um avatar 3D e proposto e um prototipo implementado. Neste sentido, um modelo de landmarks faciais separado por regioes e definido assim como uma modelagem de expressoes base utilizando as bases faciais AKDEF e JAFEE como referencia. Com este sistema e possivel representar expressoes complexas utilizando interpolacao dos valores de intensidade na animacao geometrica, de forma simplificada utilizando controle por centroides e deslocamento de regioes independentes no modelo 3D. E proposto ainda uma aplicacao de modelo espaco-temporal para os landmarks faciais, com o objetivo de observar o comportamento e relacao dos centroides na sintese das expressoes base definindo quais pontos geometricos sao relevantes no processo de interpolacao e animacao das expressoes. Um sistema de exportacao dos dados faciais seguindo o formato hierarquico utilizado na maioria dos avatares 3D interpretes de linguas de sinais e desenvolvido, incentivando a integracao em modelos formais computacionais ja existentes na literatura, permitindo ainda a adaptacao e alteracao de valores e intensidades na representacao das emocoes. Assim, os modelos e conceitos apresentados propoe a integracao de um modeo facial para representacao de expressoes na sintese de sinais oferecendo uma proposta simplificada e otimizada para aplicacao dos recursos em avatares 3D. Palavras-chave: Avatar 3D, Dados Espaco-Temporal, Libras, Lingua de sinais, Expressoes Faciais.Abstract: Formally recognized as the second official Brazilian language, BSL, or Libras, today has many computational applications that integrate the deaf community into daily activities, offering virtual interpreters represented by 3D avatars built using formal models that parameterize the specific characteristics of sign languages. These applications, however, still consider facial expressions as a background feature in a primarily gestural language, ignoring the importance that facial expressions and emotions imprint on the context of the transmitted message. In this work, in order to define a parametrized facial model for use in sign languages, a system of synthesis of facial expressions through a 3D avatar is proposed and a prototype implemented. In this way, a model of facial landmarks separated by regions is defined as a modeling of base expressions using the AKDEF and JAFEE facial bases as a reference. With this system it is possible to represent complex expressions using interpolation of the intensity values in the geometric animation, in a simplified way using control by centroids and displacement of independent regions in the 3D model. A spatial-temporal model is proposed for the facial landmarks, with the objective of define the behavior and relation of the centroids in the synthesis of the basic expressions, pointing out which geometric landmark are relevant in the process of interpolation and animation of the expressions. A system for exporting facial data following the hierarchical format used in most avatars 3D sign language interpreters is developed, encouraging the integration in formal computer models already existent in the literature, also allowing the adaptation and change of values and intensities in the representation of the emotions. Thus, the models and concepts presented propose the integration of a facial model to represent expressions in the synthesis of signals offering a simplified and optimized proposal for the application of the resources in 3D avatars. Keywords: 3D Avatar, Spatio-Temporal Data, BSL, Sign Language, Facial Expression

Using formal logic to represent sign language phonetics in semi-automatic annotation tasks

This thesis presents a formal framework for the representation of Signed Languages (SLs), the languages of Deaf communities, in semi-automatic recognition tasks. SLs are complex visio-gestural communication systems; by using corporal gestures, signers achieve the same level of expressivity held by sound-based languages like English or French. However, unlike these, SL morphemes correspond to complex sequences of highly specific body postures, interleaved with postural changes: during signing, signers use several parts of their body simultaneously in order to combinatorially build phonemes. This situation, paired with an extensive use of the three-dimensional space, make them difficult to represent with tools already existent in Natural Language Processing (NLP) of vocal languages. For this reason, the current work presents the development of a formal representation framework, intended to transform SL video repositories (corpus) into an intermediate representation layer, where automatic recognition algorithms can work under better conditions. The main idea is that corpora can be described with a specialized Labeled Transition System (LTS), which can then be annotated with logic formulae for its study. A multi-modal logic was chosen as the basis of the formal language: the Propositional Dynamic Logic (PDL). This logic was originally created to specify and prove properties on computer programs. In particular, PDL uses the modal operators [a] and to denote necessity and possibility, respectively. For SLs, a particular variant based on the original formalism was developed: the PDL for Sign Language (PDLSL). With the PDLSL, body articulators (like the hands or head) are interpreted as independent agents; each articulator has its own set of valid actions and propositions, and executes them without influence from the others. The simultaneous execution of different actions by several articulators yield distinct situations, which can be searched over an LTS with formulae, by using the semantic rules of the logic. Together, the use of PDLSL and the proposed specialized data structures could help curb some of the current problems in SL study; notably the heterogeneity of corpora and the lack of automatic annotation aids. On the same vein, this may not only increase the size of the available datasets, but even extend previous results to new corpora; the framework inserts an intermediate representation layer which can serve to model any corpus, regardless of its technical limitations. With this, annotations is possible by defining with formulae the characteristics to annotate. Afterwards, a formal verification algorithm may be able to find those features in corpora, as long as they are represented as consistent LTSs. Finally, the development of the formal framework led to the creation of a semi-automatic annotator based on the presented theoretical principles. Broadly, the system receives an untreated corpus video, converts it automatically into a valid LTS (by way of some predefined rules), and then verifies human-created PDLSL formulae over the LTS. The final product, is an automatically generated sub-lexical annotation, which can be later corrected by human annotators for their use in other areas such as linguistics.Cette thèse présente le développement d'un framework formel pour la représentation des Langues de Signes (LS), les langages des communautés Sourdes, dans le cadre de la construction d'un système de reconnaissance automatique. Les LS sont de langues naturelles, qui utilisent des gestes et l'espace autour du signeur pour transmettre de l'information. Cela veut dire que, à différence des langues vocales, les morphèmes en LS ne correspondent pas aux séquences de sons; ils correspondent aux séquences de postures corporelles très spécifiques, séparés par des changements tels que de mouvements. De plus, lors du discours les signeurs utilisent plusieurs parties de leurs corps (articulateurs) simultanément, ce qui est difficile à capturer avec un système de notation écrite. Cette situation difficulté leur représentation dans de taches de Traitement Automatique du Langage Naturel (TALN). Pour ces raisons, le travail présenté dans ce document a comme objectif la construction d'une représentation abstraite de la LS; plus précisément, le but est de pouvoir représenter des collections de vidéo LS (corpus) de manière formelle. En générale, il s'agit de construire une couche de représentation intermédiaire, permettant de faire de la reconnaissance automatique indépendamment des technologies de suivi et des corpus utilisés pour la recherche. Cette couche corresponde à un système de transition d'états (STE), spécialement crée pour représenter la nature parallèle des LS. En plus, elle peut-être annoté avec de formules logiques pour son analyse, à travers de la vérification de modèles. Pour représenter les propriétés à vérifier, une logique multi-modale a été choisi : la Logique Propositionnelle Dynamique (PDL). Cette logique a été originalement crée pour la spécification de programmes. De manière plus précise, PDL permit d'utilise des opérateurs modales comme [a] et , représentant > et >, respectivement. Une variante particulaire a été développée pour les LS : la PDL pour Langue de Signes (PDLSL), qui est interprété sur des STE représentant des corpus. Avec PDLSL, chaque articulateur du corps (comme les mains et la tête) est vu comme un agent indépendant; cela veut dire que chacun a ses propres actions et propositions possibles, et qu'il peux les exécuter pour influencer une posture gestuelle. L'utilisation du framework proposé peut aider à diminuer deux problèmes importantes qui existent dans l'étude linguistique des LS : hétérogénéité des corpus et la manque des systèmes automatiques d'aide à l'annotation. De ce fait, un chercheur peut rendre exploitables des corpus existants en les transformant vers des STE. Finalement, la création de cet outil à permit l'implémentation d'un système d'annotation semi-automatique, basé sur les principes théoriques du formalisme. Globalement, le système reçoit des vidéos LS et les transforme dans un STE valide. Ensuite, un module fait de la vérification formelle sur le STE, en utilisant une base de données de formules crée par un expert en LS. Les formules représentent des propriétés lexicales à chercher dans le STE. Le produit de ce processus, est une annotation qui peut être corrigé par des utilisateurs humains, et qui est utilisable dans des domaines d'études tels que la linguistique

The Theory and Practice of Online Learning

Every chapter in the widely distributed first edition has been updated, and four new chapters on current issues such as connectivism and social software innovations have been added. Essays by practitioners and scholars active in the complex, diverse, and rapidly evolving field of distance education blend scholarship and research; practical attention to the details of teaching and learning; and mindful attention to the economics of the business of education