Selecting input and output devices to be used in virtual walkthroughs is an important issue as it may have significant impact in usability and comfort. This paper presents a user study meant to compare the usability of two input devices used for walkthroughs in a virtual environment with a Head-Mounted Display. User performance, satisfaction, ease of use and comfort, were compared with two different input devices: a two button mouse and a joystick from a gamepad. Participants also used a desktop to perform the same tasks in order to assess if the participant groups had similar profiles. The results obtained by 45 participants suggest that both input devices have a comparable usability in the used conditions and show that participants generally performed better with the desktop; a discussion of possible causes is presented.
This paper introduces pSIVE, a platform that allows the easy setting up of Virtual Environments, with interactive information (for instance, a video or a document about a machine that is present in the virtual world) to be accessed for different 3D elements. The main goal is to create for evaluation and training on a virtual factory – but generic enough to be applied in different contexts by non-expert users (academic and touristic for instance). We show some preliminary results obtained from two different scenarios: first a production line of a factory with contextualized information associated to different elements which aimed the training of employees. Second a testing environment, to compare and assess two different selection styles that were integrated in pSIVE and to allow different users to interact with an environment created with pSIVE to collect opinions about the system. The conclusions show that the overall satisfaction was high and the comments will be considered in further platform development.
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)<sup>1</sup>. 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) <sup>2</sup>. 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) <sup>3</sup> 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.
This paper presents preliminary results on the development of a 3D audiovisual model of the <i>Anta Pintada</i> (painted
dolmen) of <i>Antelas</i>, a Neolithic chamber tomb located in <i>Oliveira de Frades</i> and listed as Portuguese national
monument. The final aim of the project is to create a highly accurate Virtual Reality (<i>VR</i>) model of this unique
archaeological site, capable of providing not only visual but also acoustic immersion based on its actual geometry and
The project started in May 2006 with <i>in situ</i> 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 (<i>ICP</i>) algorithm was developed using the <i>Visualization Toolkit </i>(<i>VTK</i>). 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 <i>VR</i> Environment comprising head-mounted display
(HMD) I-glasses <i>SVGAPro</i>, an orientation sensor (tracker) <i>InterTrax 2</i> 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 (<i>IR</i>), which carry the most significant cues for source localisation. These
early reflections are processed through Head Related Transfer Functions (<i>HRTF</i>) 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 <i>IR</i> 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 <i>IR</i> with anechoic recordings of the virtual audio source.
Virtual and Augmented Reality are developing rapidly: there is a multitude of environments and experiments in several
laboratories using from simple HMD (Head-Mounted Display) 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 such a technology are used in large scale. In addition to the fact that this is a relatively recent
technology, there is little work to validate the utility and usability of Virtual and Augmented Reality environments when
compared with the traditional desktop set-up. However, usability evaluation is crucial in order to design better systems
that respond to the users' needs, as well as for identifying applications that might really gain from the use of such
This paper presents a preliminary usability evaluation of a low-cost Virtual and Augmented Reality environment under
development at the University of Aveiro, Portugal. The objective is to assess the difference between a traditional desktop
set-up and a Virtual/Augmented Reality system based on a stereo HMD. Two different studies were performed: the first
one was qualitative and some feedback was obtained from domain experts who used an Augmented Reality set-up as well
as a desktop in different data visualization scenarios. The second study consisted in a controlled experiment meant to
compare users' performances in a gaming scenario in a Virtual Reality environment and a desktop. The overall
conclusion is that these technologies still have to overcome some hardware problems. However, for short periods of time
and specific applications, Virtual and Augmented Reality seems to be a valid alternative since HMD interaction is
intuitive and natural.