Jari Takatalo

Measuring Stereoscopic Image Quality Experience with Interpretation Based Quality Methodology

Stereoscopic technologies have developed significantly in recent years. These advances require also more understanding of the experiental dimensions of stereoscopic contents. In this article we describe experiments in which we explore the experiences that viewers have when they view stereoscopic contents. We used eight different contents that were shown to the participants in a paired comparison experiment where the task of the participants was to compare the same content in stereoscopic and non-stereoscopic form. The participants indicated their preference but were also interviewed about the arguments they used when making the decision. By conducting a qualitative analysis of the interview texts we categorized the significant experiental factors related to viewing stereoscopic material. Our results indicate that reality-likeness as well as artificiality were often used as arguments in comparing the stereoscopic materials. Also, there were more emotional terms in the descriptions of the stereoscopic films, which might indicate that the stereoscopic projection technique enhances the emotions conveyed by the film material. Finally, the participants indicated that the three-dimensional material required longer presentation time, as there were more interesting details to see.

Presence, involvement, and flow in digital games

Digital games elicit rich and meaningful experiences for the gamers. This makes games hard to study solely with usability methods that are used in the field of human–computer interaction. Here is presented a candidate framework to analyze multidimensional user experience (UX) in games. Theoretically, the framework is grounded both on previous game studies and on relevant psychological theories. Methodologically, it relies on multivariate data analysis of approximately 320 games (n = 2182), with the aim of revealing the subcomponents of UX in games. The framework captures the essential psychological determinants of UX, namely, its quality, intensity, meaning, value, and extensity. Mapping these determinants to the game mechanics, the narrative and the interface offers a rich view to UX in games and provides added value to those who want to understand why games are experienced in certain ways.

What do people look at when they watch stereoscopic movies

We measured the eye movements of participants who watched a 6-minute movie in stereoscopic and non-stereoscopic form. We analyzed four shots of the movie. The results indicate that in a 2D movie viewers tended to look at the actors, as most of the eye movements were clustered there. The significance of the actors started at the beginning of a shot, as the eyes of the viewer focused almost immediately to them. In S3D movie the eye movement patterns were more widely distributed to other targets. For example, complex stereoscopic structures and objects nearer than the actor captured the interest and eye movements of the participants. Also, the tendency to first look at the actors was diminished in the S3D shots. The results suggests that in a S3D movie there are more eye movements which are directed to wider array of objects than in a 2D movie.

User Experience in Digital Games: Differences between Laboratory and Home.

Playing entertainment computer, video, and portable games, namely, digital games, is receiving more and more attention in academic research. Games are studied in different situations with numerous methods, but little is known about if and how the playing situation affects the user experience (UX) in games. In addition, it is hard to understand and study the psychology of UX in games. The objective of this study is to show how UX differs when the first-person shooter HALO is played in a laboratory and at home. To disclose this difference, a psychologically valid and multidimensional measurement framework is introduced. UX is profiled according to the level of the sense of presence, involvement, and flow in a between-subjects design. Statistically, the structure of the framework is grounded on a large and heterogeneous gamer data set (N = 2,182). The results showed that the profile of the sense of presence in the laboratory included higher levels of attention and arousal as compared with that of the natural environment. This finding was independent of any of the measured background variables. Other differences between the two situations were more related to the participants’ background. For example, gamers at home were more involved in the game and they felt a higher level of competence. No strong emotional differences between the two situations were found. The authors discuss the complex UX terminology and implications of the framework for implementation of learning games.

Evaluation of stereoscopic image quality for mobile devices using interpretation based quality methodology

High-quality stereoscopic image content must be viewable in a variety of visual environments, from 3-D theaters to 3-D mobile devices. Stereoscopic effects, however, are affected by screen size, viewing distance, and other parameters. In this study, the authors focus on the stereoscopic image quality experience of viewing 3-D content on a mobile device in order to compare it with that of viewing 3-D content on a large screen. The stereoscopic image quality experience was evaluated using Interpretation Based Quality (IBQ) methodology, which combines existing approaches to image quality evaluation, such as the paired comparison and interview, and assesses the viewer experience using both quantitative and qualitative data. Five stereoscopic images were used in the experiment. The results of the experiment suggest that the discomfort felt while viewing stereoscopic images on a 3-D mobile device arise from not only visual fatigue but also the effects of the smaller screen size. The study also revealed the types of stereoscopic images that are suitable for viewing on 3-D mobile devices.

The movement patterns and the experiential components of virtual environments

Human movement in virtual environments (VEs) is a largely unstudied area, and there are no well-established methods of measuring it in VEs. Consequently, it is unclear how movement affects the experiential side of VEs. We introduce a novel method of measuring and modelling human movement. A specific information entropy-based modelling method enabled us to identify different movement patterns and analyse the experiential components related to them. The data was collected by registering the movement patterns of 68 participants who were in a virtual house doing a search task. The experiential side of the VE was measured with the Experimental Virtual Environment Questionnaire (EVEQ). Four movement patterns were identified. In addition, fluent movement in VEs was related to a high sense of presence. Moreover, the participants who moved fluently in the environment assessed their skills high. The results show how movement is related the way in which people experience the VE. The movement analysis method introduced here is applicable to other related research areas as well.

Determining limits to avoid double vision in an autostereoscopic display: Disparity and image element width

— The purpose of this study was to investigate the diplopia limits for three-dimensional stereoscopic content and to determine the main methodological issues when the limits are studied with an autostereoscopic display. One of the main issues regarding stereoscopic content is the structural features that enable the user to see stereo image as a single image. If the depth of the content is not within certain limits, the perceiver cannot see the images three dimensionally and the viewing is uncomfortable. On the other hand, if these limits are followed, the user can stereoscopically fuse the images and see the resulting three-dimensional image correctly. Some of these limits were tested and guidelines for proper depth values for stereoscopic images will be presented.

Measuring user experience in digital gaming: theoretical and methodological issues

There are innumerable concepts, terms and definitions for user experience. Few of them have a solid empirical foundation. In trying to understand user experience in interactive technologies such as computer games and virtual environments, reliable and valid concepts are needed for measuring relevant user reactions and experiences. Here we present our approach to create both theoretically and methodologically sound methods for quantification of the rich user experience in different digital environments. Our approach is based on the idea that the experience received from a content presented with a specific technology is always a result of a complex psychological interpretation process, which components should be understood. The main aim of our approach is to grasp the complex and multivariate nature of the experience and make it measurable. We will present our two basic measurement frameworks, which have been developed and tested in large data set (n=2182). The 15 measurement scales extracted from these models are applied to digital gaming with a head-mounted display and a table-top display. The results show how it is possible to map between experience, technology variables and the background of the user (e.g., gender). This approach can help to optimize, for example, the contents for specific viewing devices or viewing situations.

Visual comfort with mobile stereoscopic gaming

Stereoscopic display produces enhanced game playing experience for the user. However, this experience might be affected by eye strain symptoms produced by the convergence-accommodation conflict in the visual system. In this study we measured the level of sickness symptoms in mobile stereoscopic game playing situation. Our results showed that playing a mobile game with an autostereoscopic display did not cause eye strain that differed from eye strain caused by ordinary mobile device usage. The results suggest that with sufficiently small disparities a mobile stereoscopic display can be used to achieve a comfortable user experience. We also found links between experienced sickness symptoms and background variables. Firstly, our results indicated that females reported higher symptom levels than males. Secondly, we showed that the participants with higher susceptibility to motion sickness reported higher sickness levels in the experiment. Thirdly, we showed that participants with less computes skills or with less enthusiastic attitude towards new technology had significantly more sickness symptoms than the other participants.

User Experience in Digital Games

Playing entertainment computer, video, and portable games, namely, digital games, is receiving more and more attention in academic research. Games are studied in different situations with numerous methods, but little is known about if and how the playing situation affects the user experience (UX) in games. In addition, it is hard to understand and study the psychology of UX in games. The objective of this study is to show how UX differs when the first-person shooter HALO is played in a laboratory and at home. To disclose this difference, a psychologically valid and multidimensional measurement framework is introduced. UX is profiled according to the level of the sense of presence, involvement, and flow in a between-subjects design. Statistically, the structure of the framework is grounded on a large and heterogeneous gamer data set (N = 2,182). The results showed that the profile of the sense of presence in the laboratory included higher levels of attention and arousal as compared with that of the natural...