Hand gesture recognition for human computer interaction : a comparative study of different image features

Hand gesture recognition for human computer interaction, being a natural way of human computer interaction, is an area of active research in computer vision and machine learning. This is an area with many different possible applications, giving users a simpler and more natural way to communicate with robots/systems interfaces, without the need for extra devices. So, the primary goal of gesture recognition research is to create systems, which can identify specific human gestures and use them to convey information or for device control. For that, vision-based hand gesture interfaces require fast and extremely robust hand detection, and gesture recognition in real time. In this study we try to identify hand features that, isolated, respond better in various situations in human-computer interaction. The extracted features are used to train a set of classifiers with the help of RapidMiner in order to find the best learner. A dataset with our own gesture vocabulary consisted of 10 gestures, recorded from 20 users was created for later processing. Experimental results show that the radial signature and the centroid distance are the features that when used separately obtain better results, with an accuracy of 91% and 90,1% respectively obtained with a Neural Network classifier. These to methods have also the advantage of being simple in terms of computational complexity, which make them good candidates for real-time hand gesture recognition.

Hand gesture recognition system based in computer vision and machine learning

"Lecture notes in computational vision and biomechanics series, ISSN 2212-9391, vol. 19"

Generic system for human-computer gesture interaction: applications on sign language recognition and robotic soccer refereeing

Hand gestures are a powerful way for human communication, with lots of potential applications in the area of human computer interaction. Vision-based hand gesture recognition techniques have many proven advantages compared with traditional devices, giving users a simpler and more natural way to communicate with electronic devices. This work proposes a generic system architecture based in computer vision and machine learning, able to be used with any interface for human-computer interaction. The proposed solution is mainly composed of three modules: a pre-processing and hand segmentation module, a static gesture interface module and a dynamic gesture interface module. The experiments showed that the core of visionbased interaction systems could be the same for all applications and thus facilitate the implementation. For hand posture recognition, a SVM (Support Vector Machine) model was trained and used, able to achieve a final accuracy of 99.4%. For dynamic gestures, an HMM (Hidden Markov Model) model was trained for each gesture that the system could recognize with a final average accuracy of 93.7%. The proposed solution as the advantage of being generic enough with the trained models able to work in real-time, allowing its application in a wide range of human-machine applications. To validate the proposed framework two applications were implemented. The first one is a real-time system able to interpret the Portuguese Sign Language. The second one is an online system able to help a robotic soccer game referee judge a game in real time.

Generic system for human-computer gesture interaction

Hand gestures are a powerful way for human communication, with lots of potential applications in the area of human computer interaction. Vision-based hand gesture recognition techniques have many proven advantages compared with traditional devices, giving users a simpler and more natural way to communicate with electronic devices. This work proposes a generic system architecture based in computer vision and machine learning, able to be used with any interface for humancomputer interaction. The proposed solution is mainly composed of three modules: a pre-processing and hand segmentation module, a static gesture interface module and a dynamic gesture interface module. The experiments showed that the core of vision-based interaction systems can be the same for all applications and thus facilitate the implementation. In order to test the proposed solutions, three prototypes were implemented. For hand posture recognition, a SVM model was trained and used, able to achieve a final accuracy of 99.4%. For dynamic gestures, an HMM model was trained for each gesture that the system could recognize with a final average accuracy of 93.7%. The proposed solution as the advantage of being generic enough with the trained models able to work in real-time, allowing its application in a wide range of human-machine applications.

Dynamic group formation in mobile computer supported collaborative learning environment

Forming suitable learning groups is one of the factors that determine the efficiency of collaborative learning activities. However, only a few studies were carried out to address this problem in the mobile learning environments. In this paper, we propose a new approach for an automatic, customized, and dynamic group formation in Mobile Computer Supported Collaborative Learning (MCSCL) contexts. The proposed solution is based on the combination of three types of grouping criteria: learner’s personal characteristics, learner’s behaviours, and context information. The instructors can freely select the type, the number, and the weight of grouping criteria, together with other settings such as the number, the size, and the type of learning groups (homogeneous or heterogeneous). Apart from a grouping mechanism, the proposed approach represents a flexible tool to control each learner, and to manage the learning processes from the beginning to the end of collaborative learning activities. In order to evaluate the quality of the implemented group formation algorithm, we compare its Average Intra-cluster Distance (AID) with the one of a random group formation method. The results show a higher effectiveness of the proposed algorithm in forming homogenous and heterogeneous groups compared to the random method.

Crime, violência e insegurança na população jovem e sénior – um estudo exploratório no Concelho de Cabeceiras de Basto

A insegurança surge associada a um clima generalizado de ansiedade relacionada com o processo de mudanças sociais que carateriza a sociedade moderna e de que o aumento da criminalidade é uma das consequências mais visíveis (Lourenço, 2004). Este estudo tem como principal objetivo explorar os sentimentos de insegurança e medo gerados pelo fenómeno do crime e da violência nos indivíduos em meio rural em função da idade.

Homicídio nas relações de intimidade: a construção mediática do crime em homens e mulheres

Dissertação de mestrado integrado em Psicologia

Da luta contra o crime aos riscos. As consequências extra prisionais da reclusão feminina

Entre o leque de políticas penais atualmente disponíveis e legitimadas na contenção da criminalidade, a reclusão constitui a forma predominante para sancionar transgressores. Procurando alargar o debate sobre as penas de prisão, este artigo explora, através de entrevistas com 20 mulheres reclusas, os processos de reconfiguração e reestruturação das responsabilidades femininas na decorrência da reclusão de mulheres e analisa as implicações socioeconómicas da ausência feminina nos agregados domésticos. Os resultados evidenciam que a reclusão de mulheres desencadeia ou agrava posições de vulnerabilidade social e instabilidade económica, afetando sobretudo crianças, mulheres e idosos.

Do crime e do castigo. Nota de apresentação

[Excerto] Esta coletânea interdisciplinar reúne autores de várias áreas do saber que se cruzam nos estudos sociais do crime e da justiça. Se há muito estes autores colaboram entre si de várias maneiras nos respetivos trabalhos, mesmo que as linguagens conceptuais sejam diversas, é por que têm como denominadores comuns, entre outras afinidades, dois adquiridos elementares, dois fundamentos clássicos que continuam are conhecer como válidos. O primeiro mostrou ser redutor analisar o crime apenas como o resultado de um defeito individual ou de uma conduta amoral. Ele ,também, um facto social. Quem transgride a lei vive, como qualquer indivíduo, em mundos sociais que condicionam a sua existência de muitas maneiras. Não só na medida em que as possibilidades para o acatamento das leis variam consoante esses mundos - tal como nalgumas situações essa observância exige dos indivíduos muito mais esforço e resistência do que noutras -, como ainda na medida em que eles moldam com as suas lentes aquilo a que cada um dá valor ou se entende como normal.

Crime e castigo - práticas e discursos

(Excerto da nota de abertura) Há coisa de um século, um colóquio sobre a criminalidade conci­taria sem dúvida o interesse dos profissionais do direito, designada­mente dos magistrados, mas concitaria de igual modo o interesse da ciência médica, sobretudo o interesse da psiquiatria. Estaria certa­mente entre os desígnios de uma iniciativa desta natureza procurar harmonizar as propostas da psiquiatria com o regime penal. Admito que se pudesse falar também de ciências sociais, mas as ciências sociais estariam apenas no prolongamento da interrogação clínica.

Hand gesture recognition system based in computer vision and machine learning: Applications on human-machine interaction

Tese de Doutoramento em Engenharia de Eletrónica e de Computadores

Serão as práticas policiais adequadas a uma resposta imediata ao crime?

Dissertação de mestrado em Administração da Justiça

Digital literacy, technology and social inclusion: making sense of one-to-one computer programmes around the world

This book was produced in the scope of a research project entitled “Navigating with ‘Magalhães’: Study on the Impact of Digital Media in Schoolchildren”. This study was conducted between May 2010 and May 2013 at the Communication and Society Research Centre, University of Minho, Portugal and it was funded by the Portuguese Foundation for Science and Technology (PTDC/CCI-COM/101381/2008).