ESTG - Comunicações em conferências e congressos internacionais
Permanent URI for this collection
Browse
Browsing ESTG - Comunicações em conferências e congressos internacionais by Title
Now showing 1 - 10 of 398
Results Per Page
Sort Options
- 3D key-frame extraction method based on visual saliencyPublication . Ferreira, Lino; Assunção, Pedro; Cruz, Luis A. da SilvaThis paper presents a method for key-frame extraction from 3D video using visual saliency to weight the 3D content according to a user attention model. Key-frames are found in temporal segments of arbitrary length (i.e., 3D scenes) using a dynamic programming algorithm which minimises the dissimilarity between the reconstructed and the original temporal segment. The dissimilarity measure is based on a combination of frame difference and visual relevance estimated through visual saliency maps. These maps result from attention modeling, taking into account spatial, temporal and depth features of the 3D video content. The results, evaluated using the Shot Reconstruction Degree and the Fidelity measure, show that the proposed method outperforms those obtained from uniform sampling and attention curve methods. This method may be useful for fast browsing of 3D video repositories.
- 4D Light Field Disparity Map estimation using Krawtchouk PolynomialsPublication . Lourenco, Rui; Rivero-Castillo, Daniel; Thomaz, Lucas A.; Assuncao, Pedro A. A.; Tavora, Luis M. N.; Faria, Sergio M. M. deThis work presents an improved method to estimate disparity maps obtained from light field cameras using a novel edge detection algorithm based on Krawtchouk polynomials. The proposed method takes advantage of these polynomials to determine gradient information and find the edges based on automatically estimated weak and strong thresholds. The calculated edges in the gray scale epipolar plane image representation of a light field are then used to improve the accuracy of object boundaries in the the disparity map. The proposed method achieves better results when compared to other edge detection algorithms, both in terms of objective and subjective quality, specifically by reducing the mean squared error and the artifacts in the object boundaries. Furthermore, on average, the proposed method outperforms the state-of-the-art depth estimation algorithms, in terms of the objective quality of the final disparity map, namely for the commonly used HCI dataset.
- 802.21-MPA-IMS ArchitecturePublication . Rodrigues, Carlos Miguel de Jesus; Rabadão, Carlos; Pereira, AntónioMobility has become a keyword nowadays with the evolution of mobile devices market and proliferation of realtime services. IP Multimedia Subsystem (IMS) is a single, standardized service framework that supports voice, video, data and messaging services, but does not provide seamless mobility for packet based sessions. This paper purposes an IMS architecture with IEEE 802.21 and media-independent pre-authentication (MPA) integrated. IEEE 802.21 can enable this seamless mobility in IMS and, additionally, MPA provides a secure handover optimization scheme, reducing, as a consequence, handover latency. The main goal of this architecture is to provide seamless and secure handovers between different access technologies in an IMS-based environment.
- Accessibility in Software Engineering: Pursuing the Mainstream from a ClassroomPublication . Silva, João; Gonçalves, Ramiro; Martins, José; Branco, Frederico; Pereira, AntónioThough equal access to all digital devices, content and applications should be ensured by default in the Digital Age, reality has yet to match this ideal, despite the numerous efforts to raise awareness of the problem. For the visually impaired, the existence of e-accessibility issues represents a barrier that, in the majority of situations, cannot be overcome. Nevertheless, this group of individuals still insists on using digital devices, to carry out tasks from their daily lives, such as reading and writing e-mails, reading news and weather websites, and using social networks. This assumption has been validated through a survey completed by 29 blind or partially sighted individuals. Considering that the lack of depth of knowledge in developers constitutes one of the most significant constraints to the development of accessibility software and digital content, the proposal for “slide 0” to be included as an educational resource, when developers are learning how to engineer software, is discussed later in the paper. This contribution, if precisely focused on the various types of software projects, would represent a novel addition to the existing scientific literature, but also a comprehensive aid to the inclusion of e-accessibility when lecturing experts on software engineering.
- Accessibility Not on Demand - An Impaired SituationPublication . Silva, João de Sousa e; Gonçalves, Ramiro; Pereira, AntónioDigital accessibility is recognized as a fundamental tool for an egalitarian society. Nevertheless, software accessibility is an under addressed topic in the discipline of software engineering and the academy in general. As a result, its development and implementation is compromised. This problem is depicted here with the help of some experiments that shows the poor attention which is dedicated to this topic. Some hypotheses that try to explain this problem are formulated, and some possible solutions are debated. As a conclusion, some insights are given and a new possible researched avenue is presented.
- Accuracy versus complexity of MARG-based filters for remote control pointing devicesPublication . Rasteiro, Miguel ; Costelha, Hugo; Conde Bento, Luis; Assunção, PedroAlthough most current pointing devices rely on relative rotation increments, absolute orientation allows for a more intuitive interaction. However, this is difficult to implement in low-energy consumption devices since accurate fusion filters are computationally intensive. This work presents a comparative study of low-complexity filters and state-of-the-art orientation tracking systems, enabling to access complexity versus portability. A relevant set of different MARG units currently available on the market were studied under systematic tests and human subjective user analysis. Experimental results show that it is possible to obtain similar accuracy using low-complexity filters to the ones observed with state-of-the-art orientation tracking systems. © 2015 IEEE.
- Acessibilidade no Ciclo de Vida do Software: Um exercício de maiêutica na engenharia de softwarePublication . Silva, João de Sousa e; Goncalves, Ramiro; Pereira, AntónioA acessibilidade é bastante desqualificada na engenharia de software, o que compromete a sua vulgarização. Neste artigo, este problema é explicado e são evidenciadas algumas das suas consequências. São apresentados alguns conceitos chave da acessibilidade digital, que vão além da acessibilidade Web. A principal contribuição deste artigo é a apresentação de um esquisso de proposta de modelo de desenvolvimento, onde a acessibilidade está presente em todo o ciclo de vida de software, de uma forma explícita e justificada, tendo como base as quatro principais fases presentes na maioria dos modelos de desenvolvimento de software.
- Active stereo tracking of multiple free-moving targetsPublication . Perdigoto, Luis; Barreto, João P.; Caseiro, Rui; Araujo, Helder; Perdigoto, Luis;This article presents a general approach for the active stereo tracking of multiple moving targets. The problem is formulated on the plane, where cameras are modeled as ”line scan cameras” and targets are described as points with unconstrained motion. We propose to control the active system parameters in such a manner that the images of the targets in the two views are related by an homography. This homography is specified during the design stage and implicitly encodes the tracking behavior. It is shown that this formulation leads to an elegant geometric framework that enables to decide about the feasibility of a particular active tracking task. We apply it to prove that two cameras with rotation and zoom control, can track up to three moving targets, while assuring that the image location of each target is the same for both views. In addition, the framework is also useful for devising tracking strategies and deriving the required control equations. This feature is illustrated through a real experiment on tracking two independent targets using a binocular stereo head.
- An adaptive strategy for improving the performance of genetic programming-based approaches to evolutionary testingPublication . Ribeiro, José; Zenha-Rela, Mário Alberto; Vega, Francisco Fernández deThis paper proposes an adaptive strategy for enhancing Genetic Programming-based approaches to automatic test case generation. The main contribution of this study is that of proposing an adaptive Evolutionary Testing methodology for promoting the introduction of relevant instructions into the generated test cases by means of mutation; the instructions from which the algorithm can choose are ranked, with their rankings being updated every generation in accordance to the feedback obtained from the individuals evaluated in the preceding generation. The experimental studies developed show that the adaptive strategy proposed improves the algorithm's efficiency considerably, while introducing a negligible computational overhead.
- Advanced technologies for shoe sole productionPublication . Spahiu, Tatjana; Almeida, Henrique; Ascenso, Rita M. T.; Vitorino, Liliana; Marto, AnabelaAdvanced technologies for modelling and production are an important part in the whole process of product manufacturing. These advancements have changed the way of product development and play an important role in customization. In the footwear industry, as in any other industry, the use of these technologies is widely spread. Footwear comfort is one of the main selection criteria for purchase. Considering this fact, a case study of different steps for shoe designing according to individual foot shape will be presented. Taking into consideration the aesthetics of the sole and in a more sustainable view, through topological optimization reducing of material wastage for sole production will be presented. By means of the topological optimization in the shoe design process, sole optimization is realized. As a part of personalization, feet’s plantar pressure maps taken from 1 participant gave a better explanation of weight distribution of each foot. Following, sole personalization according the plantar pressure maps for each foot gives the possibility to obtain the best least material design according to the feet’s pressure while maintaining biomechanical performance.