Browsing by Author "Bidarra, Rafael"

Now showing 1 - 8 of 8
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    A Computer Graphics pioneer project on computer games
    (The Eurographics Association, 2023) Bidarra, Rafael; Dalen, Rogier van; Zwieten, Jan van; Joaquim Madeira; António Augusto de Sousa
    One of the mainsprings currently pushing the development of Computer Graphics techniques lies in the area of computer games. This motivation strongly backed the inclusion of a new project-based course on computer games within the new Computer Science curriculum, recently introduced at Delft University of Technology. This paper describes the most relevant aspects of this pioneer project. It is concluded that the cautious combination of a rather open project assignment with an effective tutoring assistance significantly can raise the level of both knowledge and teamwork skills achieved by the students.
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    Concepção e Desenvolvimento de um Modelador de Características de Forma sobre o Autocad
    (The Eurographics Association, 2023) Leitão, Gonçalo; Bidarra, Rafael; Teixeira, José Carlos; F. Mário Martins; José João Almeida; Jorge Gustavo Rocha
    A modelação de características de forma vem adquirindo cada vez maior relevo no desenvolvimento de sistemas CAD. A sua integração nestes sistemas, proporciona maiores potencialidades na concepção e manipulação dos modelos. Com este propósito, foi desenvolvido um modelador de características de fomia, tendo como suporte um sistema CAD. Na presente comunicação, são abordados os diversos problemas surgidos na concepção de tal modelador e as estruturas de dados concebidas que suportam as operações de manipulação disponibilizadas. São ainda descritas as técnicas desenvolvidas para determinar a validade dos modelos construídos e que permitem um maior grau de assistência ao projectista.
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    Direct Manipulation of Feature Models using Handles
    (The Eurographics Association, 2021) Lourenço, Daniel; Oliveira, Pedro; Bidarra, Rafael; Lopes, Adriano
    In feature based systems support for direct manipulation is not commonly available. This is partly due to the strong reliance of feature modelling systems on constraints and on the lack of speed of current constraint solv­ ers. In this paper an approach to the optimization of the geometric constraint solving for the specific situation of direct manipulation is described. Also a solution for a direct manipulation interface was designed that brings to feature modelling the advantages of direct manipulation while taking into account the main feature model­ ling paradigm concepts. Details are provided on how it was implemented successfully in the SPIFF feature mod­elling system.
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    Interactive facilities for collaborative feature modelling on the Web
    (The Eurographics Association, 2022) Bidarra, Rafael; Berg, Eelco van den; Bronsvoort, Willem F.; Joaquim Madeira; Jorge Salvador Marques; Miguel Salles Dias; Joaquim A. Jorge
    Collaborative modeling systems are distributed multiple-user systems that are both concurrent and synchronized, aimed at supporting engineering teams in coordinating their modeling activities. During a collaborative modeling session, several users are connected to each other in order to perform activities, such as design, manufacturing planning or evaluation, together, using some common product data. An interesting research challenge is to develop a collaborative modeling system that offers all facilities of advanced modeling systems to its users. This paper focuses on the interactive modeling facilities required by such collaborative modeling systems. Previous work in the area of collaborative modeling is surveyed, and several techniques for interaction with feature models are presented, ranging from display of sophisticated feature model images to interactive selection facilities, which have been implemented in the web-based collaborative feature modeling system webSPIFF. It has a client-server architecture, with an advanced feature modeling system as a basis of the server, providing feature validation, multiple views and sophisticated visualization facilities. The architecture of webSPIFF, the functionality of the server and the clients, their communication mechanisms, and the distribution of model data is described. In particular, maintenance and synchronization of model data at the clients, and techniques for their effective utilization for enhancing user interaction and collaboration are described. It is shown that a good compromise between interactivity and network load has been achieved, and that indeed advanced modeling with a collaborative system is feasible.
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    Mecanismos de raciocínio na manipulação de modelos baseados em caracteósticasde forma
    (The Eurographics Association, 2023) Bidarra, Rafael; Teixeira, José Carlos; Fernando Nunes Ferreira; João Cunha; Mári Rui Gomes; Mário Martins; Manuel João Próspero; Lima Serafim; José Carlos Teixeira
    A modelação baseada em características tem adquirido uma importância crescente no desenvolvimento de sistemas CAD, devido ao seu poder expressivo dos aspectos morfológicos contidos na intenção do projectista. O problema da integridade dum modelo baseado em características agrava-se quando a especificação de formas mais complexas requer a sobreposição ou interacção de várias características. Nesta comunicação são abordados alguns problemas relativos à validação destas características no decorrer de operações de manipulação que estabelecem ou eliminam tais imeracções. É apresentado um enquadramento semântico baseado na expressão semântica do comportamento pretendido para cada classe de características, a fim de estabelecer condições de validade que se suportem um grau arbitrário de imeracções. Exemplificam-se alguns mecanismos de raciocínio para realizar a validação automática de características, realçando a sua fácil integração com uma representação celular adequada para captar a morfologia local de um modelo baseado em características de forma.
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    Usability in Virtual and Augmented Environments: A qualitative study
    (The Eurographics Association, 2021) Pimentel, Angela; Dias, Paulo; Huussen, Frank van; Horst, Pauline van der; Baggerman, Jan-Willem; Bidarra, Rafael; Madeira, Joaquim; Santos, Beatriz Sousa; Chambel, Teresa and Nunes, Nuno and Romao, Teresa and Creissac Campos, José
    Virtual and Augmented reality are developing rapidly: there is a multitude of environments and experiments in several laboratories using from simple HMD visualization to more complex and expensive 6-wall projection, CAVEs, and other systems. Still there is not yet a clear emerging technology in this area, nor commercial applications based on this technology are used in large scale. In addition to the fact that this is an emerging and relatively recent technology, there is little work to validate the utility and usability of these Virtual and Augmented environments when compared with traditional desktops. However, usability evaluation is crucial in order to design better systems that respond to the users' needs, as well as for finding applications that can really gain from the use of these new technologies. In this short paper, we present a preliminary qualitative usability study of a Virtual and Augmented Reality environment under development at the University of Aveiro. The main goal is to find clues on how to develop better evaluation methods for systems based on AR/VR technologies.
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    Validity Maintenance of Models with Interacting Features
    (The Eurographics Association, 2023) Bidarra, Rafael; Bronsvoort, Willem F.; António Augusto de Sousa; José Carlos Teixeira
    Current feature-based modelling systems fail to adequately maintain feature semantics. This is partly due to inappropriate specification of validity conditions in feature classes, but mainly due to a Jack of effective validity maintenance mechanisms throughout the modelling process. An essential aspect in this is feature interaction management. This paper presents a new approach to the detection of feature interactions, which uses semantic and interaction constraints in feature class specification. Validity maintenance is automatically performed after each modelling operation by checking these constraints, thus being able to detect a variety of interaction types. Such interactions are then analyzed, and their causes identified and reported to the user.
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    Web-based direct manipulation of feature models
    (The Eurographics Association, 2021) Bidarra, Rafael; Bunnik, Andre van; Bronsvoort, Willem F.; Marcos, Adérito and Mendonça, Ana and Leitão, Miguel and Costa, António and Jorge, Joaquim
    Providing advanced 3D interactive facilities to users of a client-server collaborative modeling system presents a great challenge when thin clients are involved, mainly due to their lack of both a proper CAD model and the adequate modeling and solving functionality. This paper presents a new approach that provides a convenient representation of feature model data suitable for direct manipulation of feature models at such clients. It combines all advantages of a thin client approach with the sort of 3D direct manipulation facilities usually only found in powerful standalone CAD systems.