Application of Visual-Inertial SLAM for 3D Mapping of Underground Environments

The underground scenarios are one of the most challenging environments for accurate and precise 3d mapping where hostile conditions like absence of Global Positioning Systems, extreme lighting variations and geometrically smooth surfaces may be expected. So far, the state-of-the-art methods in underground modelling remain restricted to environments in which pronounced geometric features are abundant. This limitation is a consequence of the scan matching algorithms used to solve the localization and registration problems. This paper contributes to the expansion of the modelling capabilities to structures characterized by uniform geometry and smooth surfaces, as is the case of road and train tunnels. To achieve that, we combine some state of the art techniques from mobile robotics, and propose a method for 6DOF platform positioning in such scenarios, that is latter used for the environment modelling. A visual monocular Simultaneous Localization and Mapping (MonoSLAM) approach based on the Extended Kalman Filter (EKF), complemented by the introduction of inertial measurements in the prediction step, allows our system to localize himself over long distances, using exclusively sensors carried on board a mobile platform. By feeding the Extended Kalman Filter with inertial data we were able to overcome the major problem related with MonoSLAM implementations, known as scale factor ambiguity. Despite extreme lighting variations, reliable visual features were extracted through the SIFT algorithm, and inserted directly in the EKF mechanism according to the Inverse Depth Parametrization. Through the 1-Point RANSAC (Random Sample Consensus) wrong frame-to-frame feature matches were rejected. The developed method was tested based on a dataset acquired inside a road tunnel and the navigation results compared with a ground truth obtained by post-processing a high grade Inertial Navigation System and L1/L2 RTK-GPS measurements acquired outside the tunnel. Results from the localization strategy are presented and analyzed.

Smart object for 3D interaction

This paper reports on the creation of an interface for 3D virtual environments, computer-aided design applications or computer games. Standard computer interfaces are bound to 2D surfaces, e.g., computer mouses, keyboards, touch pads or touch screens. The Smart Object is intended to provide the user with a 3D interface by using sensors that register movement (inertial measurement unit), touch (touch screen) and voice (microphone). The design and development process as well as the tests and results are presented in this paper. The Smart Object was developed by a team of four third-year engineering students from diverse scientific backgrounds and nationalities during one semester.

Amygdala activation in response to 2D and 3D emotion-inducing stimuli

Studying changes in brain activation according to the valence of emotion-inducing stimuli is essential in the research on emotions. Due to the ecological potential of virtual reality, it is also important to examine whether brain activation in response to emotional stimuli can be modulated by the three-dimensional (3D) properties of the images. This study uses functional Magnetic Resonance Imaging to compare differences between 3D and standard (2D) visual stimuli in the activation of emotion-related brain areas. The stimuli were organized in three virtual-reality scenarios, each with a different emotional valence (pleasant, unpleasant and neutral). The scenarios were presented in a pseudo-randomized order in the two visualization modes to twelve healthy males. Data were analyzed through a GLM-based fixed effects procedure. Unpleasant and neutral stimuli activated the right amygdala more strongly when presented in 3D than in 2D. These results suggest that 3D stimuli, when used as “building blocks” for virtual environments, can induce increased emotional loading, as shown here through neuroimaging.

Projeto topológico de uma rede rodoviária

Mestrado em Engenharia Informática - Área de Especialização em Sistemas Gráficos e Multimédia

Teaching with Moodle in higher education

Nowadays, with the use of technology and the Internet, education is undergoing significant changes, contemplating new ways of teaching and learning. One of the widely methods of teaching used to promote knowledge, consists in the use of virtual environments available in various formats, taking as example the teaching-learning platforms, which are available online. The Internet access and use of Laptops have created the technological conditions for teachers and students can benefit from the diversity of online information, communication, collaboration and sharing with others. The integration of Internet services in the teaching practices can provide thematic, social and digital enrichment for the agents involved. In this paper we will talk about the advantages of LMS (Learning Management Systems) such as Moodle, to support the presential lectures in higher education. We also will analyse its implications for student support and online interaction, leading educational agents to a mixing of different learning environments, where they can combine face-to-face instruction with computer-mediated instruction, blended-learning, and increases the options for better quality and quantity of human interaction in a learning environment. We also will present some tools traditionally used in online assessment and that are part of the functionalities of Moodle. These tools can provide interesting alternatives to promote a more significant learning and contribute to the development of flexible and customized models of an evaluation which we want to be more efficient.

Simulation Environment for Multi-Robot Cooperative 3D Target Perception

4th International Conference, SIMPAR 2014, Bergamo, Italy, October 20-23, 2014

Multi-agent electricity market simulation with dynamic strategies & virtual power producers

Distributed energy resources will provide a significant amount of the electricity generation and will be a normal profitable business. In the new decentralized grid, customers will be among the many decentralized players and may even help to co-produce the required energy services such as demand-side management and load shedding. So, they will gain the opportunity to be more active market players. The aggregation of DG plants gives place to a new concept: the Virtual Power Producer (VPP). VPPs can reinforce the importance of these generation technologies making them valuable in electricity markets. In this paper we propose the improvement of MASCEM, a multi-agent simulation tool to study negotiations in electricity spot markets based on different market mechanisms and behavior strategies, in order to take account of decentralized players such as VPP.

Multi-agent systems and birtual producers in electronic marketplaces

This paper presents an agent-based simulator designed for analyzing agent market strategies based on a complete understanding of buyer and seller behaviours, preference models and pricing algorithms, considering user risk preferences. The system includes agents that are capable of improving their performance with their own experience, by adapting to the market conditions. In the simulated market agents interact in several different ways and may joint together to form coalitions. In this paper we address multi-agent coalitions to analyse Distributed Generation in Electricity Markets

Visualização e manipulação de informação em ambientes 3D imersivos

Ainda antes da invenção da escrita, o desenho foi utilizado para descrever a realidade, tendo evoluído ao longo dos tempos, ganhando mais qualidade e pormenor e recorrendo a suportes cada vez mais evoluídos que permitissem a perpetuação dessa imagem: dessa informação. Desde as pinturas rupestres, nas paredes de grutas paleolíticas, passando pelos hieróglifos, nos templos egípcios, nas gravuras das escrituras antigas e nos quadros sobre tela, a intenção sempre foi a de transmitir a informação da forma mais directa e perceptível por qualquer indivíduo. Nos dias de hoje as novas tecnologias permitem aceder à informação com uma facilidade nunca antes vista ou imaginada, estando certamente ainda por descobrir outras formas de registar e perpetuar a informação para as gerações vindouras. A fotografia está na origem das grandes evoluções da imagem, permitindo capturar o momento, tornando-o “eterno”. Hoje em dia, na era da imagem digital, além de se mostrar a realidade, é possível incorporar na imagem informação adicional, de modo a enriquecer a experiência de visualização e a maximizar a aquisição do conhecimento. As possibilidades da visualização em três dimensões (3D) vieram dar o realismo que faltava ao formato de fotografia original. O 3D permite a imersão do espectador no ambiente que, a própria imagem retrata, à qual se pode ainda adicionar informação escrita ou até sensorial como, por exemplo, o som. Esta imersão num ambiente tridimensional permite ao utilizador interagir com a própria imagem através da navegação e exploração de detalhes, usando ferramentas como o zoom ou ligações incorporados na imagem. A internet é o local onde, hoje em dia, já se disponibilizam estes ambientes imersivos, tornando esta experiência muita mais acessível a qualquer pessoa. Há poucos anos ainda, esta prática só era possível mediante o recurso a dispositivos especificamente construídos para o efeito e que, por isso, apenas estavam disponíveis a grupos restritos de utilizadores. Esta dissertação visa identificar as características de um ambiente 3D imersivo e as técnicas existentes e possíveis de serem usadas para maximizar a experiência de visualização. Apresentar-se-ão algumas aplicações destes ambientes e sua utilidade no nosso dia-a-dia, antevendo as tendências futuras de evolução nesta área. Serão apresentados exemplos de ferramentas para a composição e produção destes ambientes e serão construídos alguns modelos ilustrativos destas técnicas, como forma de avaliar o esforço de desenvolvimento e o resultado obtido, comparativamente com formas mais convencionais de transmitir e armazenar a informação. Para uma avaliação mais objectiva, submeteram-se os modelos produzidos à apreciação de diversos utilizadores, a partir da qual foram elaboradas as conclusões finais deste trabalho relativamente às potencialidades de utilização de ambientes 3D imersivos e suas mais diversas aplicações.

A realidade virtual como factor de atracção para a engenharia

O objectivo da Realidade Virtual é simples de entender mas muito difícil de implementar: criar ambientes completamente indiferenciáveis do mundo real com os quais se possa interagir de um modo natural. Desde a criação do Sensorama por Morton Heiling em 1962, passando pela difusão do conceito pelo público geral na década de 90 até os dias de hoje, a evolução da Realidade Virtual tem sido constante. Este conjunto de tecnologias tem estado envolvido por uma certa descrença por parte da sociedade, motivada pelas grandes expectativas que lhe foram atribuídas e pelo estado de desenvolvimento do hardware aquando do seu auge. No entanto, actualmente assiste-se a um ressurgimento do seu interesse no público geral com a introdução de imagem estereoscópica no cinema ou o sucesso dos controladores da consola Nintendo Wii. Hoje em dia as suas aplicações são muito variadas: desde o treino de pilotos de avião ao tratamento de fobias, passando pela industria do entretenimento e a visita virtual de locais com interesse histórico ou turístico. O objectivo desta tese de mestrado é explorar uma área que ainda não tem sido muito abrangida pela Realidade Virtual e que cobre também aspectos educacionais e lúdicos de modo a ser um factor de atracção para os estudantes do ensino secundário: a simulação de instrumentos musicais. Para tal foi implementado um sistema capaz de simular instrumentos musicais de percussão (uma bateria) utilizando imagem estereoscópica, som posicional e interfaces com o utilizador realistas. Os resultados obtidos nas sessões de avaliação efectuadas por alunos recentemente ingressados no ensino superior demonstram que o sistema desenvolvido, bem como a inovação em interfaces do utilizador com os dispositivos electrónicos de uma forma geral, constituem um meio efectivo na sua motivação para a escolha de um curso na área da engenharia.

Workload balancing in distributed virtual reality environments

Virtual Reality (VR) has grown to become state-of-theart technology in many business- and consumer oriented E-Commerce applications. One of the major design challenges of VR environments is the placement of the rendering process. The rendering process converts the abstract description of a scene as contained in an object database to an image. This process is usually done at the client side like in VRML [1] a technology that requires the client’s computational power for smooth rendering. The vision of VR is also strongly connected to the issue of Quality of Service (QoS) as the perceived realism is subject to an interactive frame rate ranging from 10 to 30 frames-per-second (fps), real-time feedback mechanisms and realistic image quality. These requirements overwhelm traditional home computers or even high sophisticated graphical workstations over their limits. Our work therefore introduces an approach for a distributed rendering architecture that gracefully balances the workload between the client and a clusterbased server. We believe that a distributed rendering approach as described in this paper has three major benefits: It reduces the clients workload, it decreases the network traffic and it allows to re-use already rendered scenes.

Extended immersive learning environment: a hybrid remote/virtual laboratory

This paper presents a collaborative virtual learning environment, which includes technologies such as 3D virtual representations, learning and content management systems, remote experiments, and collaborative learning spaces, among others. It intends to facilitate the construction, management and sharing of knowledge among teachers and students, in a global perspective. The environment proposes the use of 3D social representations for accessing learning materials in a dynamic and interactive form, which is regarded to be closer to the physical reality experienced by teachers and students in a learning context. A first implementation of the proposed extended immersive learning environment, in the area of solid mechanics, is also described, including the access to theoretical contents and a remote experiment to determine the elastic modulus of a given object.These instructions give you basic guidelines for preparing camera-ready papers for conference proceedings. Use this document as a template if you are using Microsoft Word 6.0 or later. Otherwise, use this document as an instruction set. The electronic file of your paper will be formatted further. Define all symbols used in the abstract. Do not cite references in the abstract.

Towards high-available and energy-efficient virtual computing environments in the cloud

Empowered by virtualisation technology, cloud infrastructures enable the construction of flexi- ble and elastic computing environments, providing an opportunity for energy and resource cost optimisation while enhancing system availability and achieving high performance. A crucial re- quirement for effective consolidation is the ability to efficiently utilise system resources for high- availability computing and energy-efficiency optimisation to reduce operational costs and carbon footprints in the environment. Additionally, failures in highly networked computing systems can negatively impact system performance substantially, prohibiting the system from achieving its initial objectives. In this paper, we propose algorithms to dynamically construct and readjust vir- tual clusters to enable the execution of users’ jobs. Allied with an energy optimising mechanism to detect and mitigate energy inefficiencies, our decision-making algorithms leverage virtuali- sation tools to provide proactive fault-tolerance and energy-efficiency to virtual clusters. We conducted simulations by injecting random synthetic jobs and jobs using the latest version of the Google cloud tracelogs. The results indicate that our strategy improves the work per Joule ratio by approximately 12.9% and the working efficiency by almost 15.9% compared with other state-of-the-art algorithms.

Virtual Communities of Practice: Design and Development of Support Platforms and Participation Fostering

Mestrado em Engenharia Informática - Área de Especialização em Sistemas Gráficos e Multimédia

Uncertainty based Multi-Robot Cooperative Triangulation

The paper presents a multi-robot cooperative framework to estimate the 3D position of dynamic targets, based on bearing-only vision measurements. The uncertainty of the observation provided by each robot equipped with a bearing-only vision system is effectively addressed for cooperative triangulation purposes by weighing the contribution of each monocular bearing ray in a probabilistic manner. The envisioned framework is evaluated in an outdoor scenario with a team of heterogeneous robots composed of an Unmanned Ground and Aerial Vehicle.