2017
Authors
Barbosa, L; Monteiro, P; Pinto, M; Coelho, H; Melo, M; Bessa, M;
Publication
2017 24 ENCONTRO PORTUGUES DE COMPUTACAO GRAFICA E INTERACAO (EPCGI)
Abstract
The use of virtual reality in training and simulation as well as the use of haptic feedback are already used in many areas such as medicine, aviation, and training in controlled environments, such as training firefighters. The purpose of this study was the creation of a virtual multisensory environment for the simulation of a training task used in the training of firemen, with the added purpose of studying the impact of the use of haptic feedback on the feeling of presence, satisfaction and performance in the task. For this study a virtual reality experiment was designed to simulate an urban fire environment, where the participants had to train one of the methods used by firefighters in these situations, and the temperature was selected for the haptic feedback. The analysis to the obtained data show that, after doing the experiment, the performance with and without haptic feedback was approximately the same and the participants showed a low error rate. Regarding the sense of presence and satisfaction, the results demonstrate that there was an improvement in the involvement and experienced realism, as well as a low cybersickness value.
2018
Authors
Melo, M; Vasconcelos Raposo, J; Bessa, M;
Publication
COMPUTERS & GRAPHICS-UK
Abstract
As the usage of head-mounted displays (HMD) increases, it is important to establish best usage practices to ensure the appropriate use of Virtual Reality (VR) equipment. Among the factors that can contribute to a better user experience are exposure time, the content type and the gender of the user. This study evaluates the impact of these variables on users' Sense of Presence and Cybersickness when visualising 360 content using HMDs. Two types of 360 content (captured video vs. virtual environment) were evaluated across four different exposure times (1, 3, 5 and 7 min). Regarding Sense of Presence, the results revealed a statistically significant difference for Content Type, Gender, and Content Type x Gender. Regarding Cybersickness, no statistically significant results were found for any of the independent variables. Overall, the results encourage the use of synthesized environments for a female audience; for non-interactive environments, captured environments are more effective than synthesized environments; and exposure time is not a concern for experiences lasting between 1 and 7 min.
2017
Authors
Carvalho, D; Bessa, M; Magalhaes, L; Melo, M; Carrapatoso, E;
Publication
2017 24 ENCONTRO PORTUGUES DE COMPUTACAO GRAFICA E INTERACAO (EPCGI)
Abstract
The traditional attitude towards user interfaces has changed. The Post-WIMP era has brought about novel input modalities such as touch, tangibles or gestures that allow users to manipulate digital contents more intuitively. These novel input modalities make use of the users' innate skills instead of imposing the learning of new interaction techniques. Nonetheless, there has not been a systematic evaluation on how, or if, these interfaces influence the users' performance and/or preference: distinct interfaces may be more or less appropriate regarding different age groups, user profiles, contexts or type of tasks. This work is a preliminary evaluation on whether the users' efficiency is indeed influenced by different input modalities or age. We conducted a target acquisition performance evaluation with 60 subjects to understand how different input modalities influence the speed and accuracy of three specific age groups (children, young adults and older-adults) when dealing with a continuous selection task. Three input modalities were considered to perform the task (mouse, touch and gestures) and the methodology was based on Fitts' law, a target acquisition performance evaluation model. Overall, when comparing movement times amongst the three groups, there are significant differences between age groups regarding the index of performance. We believe our findings may show that indeed the type of input modality used and the user's age could affect one's performance.
2014
Authors
Melo, M; Bessa, M; Debattista, K; Chalmers, A;
Publication
SIGNAL PROCESSING-IMAGE COMMUNICATION
Abstract
Tone mapping operators (TMOs) allow the visual appearance of High Dynamic Range (HDR) video to be reproduced on Low Dynamic Range (LDR) displays. While several studies have been made to compare the performance of different TMOs on standard displays, there is only one preliminary study that takes into account the characteristics of Small Screen Devices (SSDs) which are common on mobile platforms that are growing rapidly in popularity. Due to the unique characteristics of mobile devices, the variety of viewing conditions where they are used, and the fact that they are becoming so widespread, it is important to identify what is the best method to deliver HDR video content to these devices. This paper presents an evaluation of HDR video on mobile devices using an HDR display as reference. Six state-of-the-art HDR video tone mappers are evaluated by conducting a psychophysical experiment where participants were asked to rank the tone mappers applied to different HDR video footage. A comparison was made between tone mapped HDR video footage shown on a tablet and an LCD display compared with the same HDR video footage shown simultaneously on an HDR display. This study shows there is a subtle but statistically significant difference in the preference of TMOs between SSD and LDR even though the overall ordering of TMOs is the same across both displays.
2016
Authors
Silva, RBR; Teixeira, CM; Vasconcelos Raposo, J; Bessa, M;
Publication
COMPUTERS IN HUMAN BEHAVIOR
Abstract
This is the first research that aim to analyze the practice of Sexting in Portugal. The goals of this study included comparing the differences between the Sexting dimensions and independent factors (gender, age, literacy qualifications, profession, residence, marital status, existence of a stable relationship, most used media, place of frequent use of the media, most commonly used technological device, security perception of communication technology, number of text messages sent per day, recipients of text messages) and corroborating the existence of correlations between the Sexting dimensions. The study sample consisted of 301 individuals aged between 18 and 52 years (158 adults and 143 young adults) and included both females (169) and males (132). The instruments used included a translated and adapted version of the Sex and Tech Survey, created by The National Campaign to Prevent Teen and Unplanned Pregnancy, and the elaboration of 7 social and demographic questions and 6 questions about media consumption and daily technology use. The results showed that environment exposure was higher in males as well as in the group of individuals of both sexes who sent approximately 76-90 written messages per day. By contrast, positive emotions and the development of greater interest in Sexting were higher in women. Positive emotions were higher in young adults, students of both sexes and unemployed persons.
2016
Authors
Melo, Miguel; Rocha, Tania; Barbosa, Luis; Bessa, Maximino;
Publication
Proceedings of the 7th International Conference on Software Development and Technologies for Enhancing Accessibility and Fighting Info-exclusion, DSAI 2016, Vila Real, Portugal, December 1-3, 2016
Abstract
There is a trend towards the use of Virtual Reality (VR) environments and its evolution has promoted new interaction approaches so there is a need for studying a number of factors that can have impact on its usability. This paper studies the impact of the body position on the usability of VR environments. For the effect, a case study was undertaken based on a bicycle ride that considers two body positions: riding the bicycle seated with the feet on the pedals and hands in the handlebar; and standing with the feet on the ground and the hands on the handlebar. On both cases they had control over the bicycle (steer and brakes). These two body positions were considered as they will allow studying in detail the impact of the different body positions: the first condition mimics the real body position of the depicted scenario while the second condition tests an alternate body position. Results regarding the system's effectiveness have shown an 100% success rate as all participants concluded the task successfully and there were no dropouts. The efficiency results have revealed that the more the participants used the VE the less the number of errors they made and that the completion time differences between the tested conditions were insignificant (> 0.5 seconds). As for satisfaction, participants reported a preference towards the standing position. Furthermore, results reveal that body position has impact on the users' performance but it does not necessarily affect their satisfaction over the virtual experience. © 2016 ACM.
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