ICAT-EGVE2014

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https://diglib.eg.org/handle/10.2312/7758

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Browsing ICAT-EGVE2014 by Subject "I.3.7 [Computer Graphics]"

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    Neural Correlates of Disrupted Presence: Strange Disruptions in a Naturalistic Virtual Environment
    (The Eurographics Association, 2014) Sjoelie, Daniel; Kalpouzos, Gregoria; Eriksson, Johan; Takuya Nojima and Dirk Reiners and Oliver Staadt
    The concept of presence is commonly related to whether or not a user feels, acts, and reacts as if he/she were in a real familiar environment when using a virtual reality (VR) application. Understanding the neural correlates of presence may provide a foundation for objective measurements and important constraints for theoretical explanations. Here, we focus on the importance of expectations and their violation in several theoretical descriptions of presence in order to investigate neural correlates of disrupted presence. Functional magnetic resonance imaging (fMRI) was used to measure brain activity during execution of everyday tasks in a naturalistic virtual environment (VE). Time periods with disrupted presence were identified using subject reports of strange situations, interpreted as violations of expectations related to the sense of presence. Disrupted presence was associated with increased activity in the frontopolar cortex (FPC), lateral occipito-temporal cortex (LOTC), the temporal poles (TP), and the posterior superior temporal cortex (pSTC). We relate these areas to integration of key aspects of a presence experience, relating the (changing) situation to management of task and goals (FPC), interpretation of visual input (LOTC), emotional evaluation of the context (TP) and possible interactions (pSTC). These results are consistent with an interpretation of disrupted presence as a re-evaluation of key aspects of a subjective mental reality, updating the synchronization with the virtual environment as previous predictions fail. Such a subjective mental reality may also be related to a self-centered type of mentalization, providing a link to accounts of presence building on the self.
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    A New Direct Manipulation Technique for Immersive 3D Virtual Environments
    (The Eurographics Association, 2014) Nguyen, Thi-Thuong Huyen; Duval, Thierry; Pontonnier, Charles; Takuya Nojima and Dirk Reiners and Oliver Staadt
    In this paper, we introduce a new 7-Handle manipulation technique for 3D objects in immersive virtual environments and its evaluation. The 7-Handle technique includes a set of seven points which are flexibly attached to an object. There are three different control modes for these points including configuration, manipulation and locking / unlocking modes. We have conducted an experiment to compare the efficiency of this technique with the traditional 6-DOF direct manipulation technique in terms of time, discomfort metrics and subjective estimation for precise manipulations in an immersive virtual environment in two consecutive phases: an approach phase and a refinement phase. The statistical results showed that the completion time in the approach phase of the 7-Handle technique was significantly longer than the completion time of the 6-DOF technique. Nevertheless, we found a significant interaction effect between the two factors (the manipulation technique and the object size) on the completion time of the refinement phase. In addition, even though we did not find any significant differences between the two techniques in terms of intuitiveness, ease of use and global preference in the result of subjective data, we obtained a significantly better satisfaction feedback from the subjects for the efficiency and fatigue criteria.