Dr. Paulo M. Dias Profile

Dr. Paulo M. Dias

at Univ de Aveiro

SPIE Involvement:

Author

Publications (5)

Proceedings Article | 28 February 2014 Paper

Platform for setting up interactive virtual environments

Danilo Souza, Paulo Dias, Daniel Santos, Beatriz Sousa Santos

Proceedings Volume 9012, 90120O (2014) https://doi.org/10.1117/12.2038668

KEYWORDS: Virtual reality, 3D modeling, Head, Instrument modeling, Video, Head-mounted displays, Multimedia, Software development, Visualization, Computing systems

Read Abstract +

Proceedings Article | 28 February 2014 Paper

Comparing two input devices for virtual walkthroughs using a Head Mounted Display (HMD)

Beatriz Sousa Santos, Paulo Dias, Paulo Santos, Carlos Ferreira

Proceedings Volume 9012, 90120M (2014) https://doi.org/10.1117/12.2036486

KEYWORDS: Head-mounted displays, Virtual reality, Head, Human-machine interfaces, Image resolution, Visualization, Velocity measurements, Computing systems, Statistical analysis, Electronic imaging

Read Abstract +

Proceedings Article | 3 February 2014 Paper

Evaluation in visualization: some issues and best practices

Beatriz Sousa Santos, Paulo Dias

Proceedings Volume 9017, 90170O (2014) https://doi.org/10.1117/12.2038259

KEYWORDS: Visualization, Taxonomy, Visual analytics, Information visualization, Testing and analysis, Data analysis, Data modeling, Data visualization, Statistical analysis, Optimization (mathematics)

Read Abstract +

The first data and information visualization techniques and systems were developed and presented without a systematic evaluation; however, researchers have become, and are more and more, aware of the importance of evaluation (Plaisant, 2004)¹. Evaluation is not only a means of improving techniques and applications, but it can also produce evidence of measurable benefits that will encourage adoption. Yet, evaluating visualization applications or techniques, is not simple. We deem visualization applications should be developed using a user-centered design approach and that evaluation should take place in several phases along the process and with different purposes. An account of what issues we consider relevant while planning an evaluation in Medical Data Visualization can be found in (Sousa Santos and Dillenseger, 2005) ². In that work the question “how well does a visualization represent the underlying phenomenon and help the user understand it?” is identified as fundamental, and is decomposed in two aspects: A) the evaluation of the representation of the phenomenon (first part of the question). B) the evaluation of the users’ performance in their tasks when using the visualization, which implies the understanding of the phenomenon (second part of the question). We contend that these questions transcend Medical Data Visualization and can be considered central to evaluating Data and Information Visualization applications and techniques in general. In fact, the latter part of the question is related to the question Freitas et al. (2009) ³ deem crucial to user centered visualization evaluation: “How do we know if information visualization tools are useful and usable for real users performing real visualization tasks?” In what follows issues and methods that we have been using to tackle this latter question, are briefly addressed. This excludes equally relevant topics as algorithm optimization, and accuracy, that can be dealt with using concepts and methods well known in other disciplines and are mainly related to how well the phenomenon is represented. A list of guidelines considered as our best practices to perform evaluations is presented and some conclusions are drawn.

Proceedings Article | 10 March 2008 Paper

3D reconstruction and spatial auralization of the Painted Dolmen of Antelas

Paulo Dias, Guilherme Campos, Vítor Santos, Ricardo Casaleiro, Ricardo Seco, Beatriz Sousa Santos

Proceedings Volume 6805, 68050Y (2008) https://doi.org/10.1117/12.766607

KEYWORDS: 3D modeling, Acoustics, Reflection, Visualization, Head, Clouds, Visual process modeling, Absorption, 3D acquisition, Reconstruction algorithms

Read Abstract +

This paper presents preliminary results on the development of a 3D audiovisual model of the Anta Pintada (painted dolmen) of Antelas, a Neolithic chamber tomb located in Oliveira de Frades and listed as Portuguese national monument. The final aim of the project is to create a highly accurate Virtual Reality (VR) model of this unique archaeological site, capable of providing not only visual but also acoustic immersion based on its actual geometry and physical properties. The project started in May 2006 with in situ data acquisition. The 3D geometry of the chamber was captured using a Laser Range Finder. In order to combine the different scans into a complete 3D visual model, reconstruction software based on the Iterative Closest Point (ICP) algorithm was developed using the Visualization Toolkit (VTK). This software computes the boundaries of the room on a 3D uniform grid and populates its interior with "free-space nodes", through an iterative algorithm operating like a torchlight illuminating a dark room. The envelope of the resulting set of "free-space nodes" is used to generate a 3D iso-surface approximating the interior shape of the chamber. Each polygon of this surface is then assigned the acoustic absorption coefficient of the corresponding boundary material. A 3D audiovisual model operating in real-time was developed for a VR Environment comprising head-mounted display (HMD) I-glasses SVGAPro, an orientation sensor (tracker) InterTrax 2 with 3 Degrees Of Freedom (3DOF) and stereo headphones. The auralisation software is based on a geometric model. This constitutes a first approach, since geometric acoustics have well-known limitations in rooms with irregular surfaces. The immediate advantage lies in their inherent computational efficiency, which allows real-time operation. The program computes the early reflections forming the initial part of the chamber's impulse response (IR), which carry the most significant cues for source localisation. These early reflections are processed through Head Related Transfer Functions (HRTF) updated in real-time according to the orientation of the user's head, so that sound waves appear to come from the correct location in space, in agreement with the visual scene. The late-reverberation tail of the IR is generated by an algorithm designed to match the reverberation time of the chamber, calculated from the actual acoustic absorption coefficients of its surfaces. The sound output to the headphones is obtained by convolving the IR with anechoic recordings of the virtual audio source.

Proceedings Article | 5 March 2007 Paper

Usability in virtual and augmented environments: a qualitative and quantitative study

Paulo Dias, Angela Pimentel, Carlos Ferreira, Frank van Huussen, Jan-Willem Baggerman, Pauline van der Horst, Joaquim Madeira, Rafael Bidarra, Beatriz Sousa Santos

Proceedings Volume 6490, 64901I (2007) https://doi.org/10.1117/12.703878

KEYWORDS: Virtual reality, Augmented reality, Head-mounted displays, Cameras, Visualization, Data modeling, 3D modeling, Statistical analysis, Video, Lung

Read Abstract +

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years