A Study on Evaluation of Visual Factor for Measuring Subjective Virtual Realization

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1 , Vol.15, No.3, pp , September 2012 A Study on Evaluation of Visual Factor for Measuring Subjective Virtual Realization * * * *** ** Myeung Ju Won* Sang In Park* Chi Jung Kim* Eui Chul Lee*** MinCheol Whang** * *Department of Emotion Engineering, Sangmyung University ** **Department of Digital Media, Sangmyung University *** ***Department of Computer Science, Sangmyung University Abstract Virtual worlds have pursued reality as if they actually exist. In order to evaluate the sense of reality in the computer-simulated worlds, several subjective questionnaires, which include specific independent variables, have been proposed in the literature. However, the questionnaires lack reliability and validity necessary for defining and measuring the virtual realization. Few studies have been conducted to investigate the effect of visual factors on the sense of reality experienced by exposing to a virtual environment. Therefore, this study was aimed at reinvestigating the variables and proposing a more reliable and advisable questionnaire for evaluating the virtual realization, focusing on visual factors. Twenty-one questions were gleaned from the literature and subjective interviews with focused groups. Exploratory factor analysis with oblique rotation was performed on the data obtained from 200 participants(females: 100) after exposing to a virtual character image described in an extreme way. After removing poorly loading items, remained subsets were subjected to confirmatory factor analysis on the data obtained from the same participants. As a result, 3 significant factors were determined to efficiently measure the virtual realization. The determined factors included visual presence(3 subset items), visual immersion(7 subset items), and visual interactivity(4 subset items). The proposed factors were verified by conducting a subjective evaluation in which participants were asked to evaluate a 3D virtual eyeball model based on the visual presence. The results implicated 2011 ( ) (NO ). ( ) 2010 < > ( -M1AXA ). ( ) whang@smu.ac.kr TEL FAX

2 that the measurement method was suitable for evaluating the degree of the virtual realization. The proposed method is expected to reasonably measure the degree of the virtual realization. - VnR(Virtual and Real worlds)..,..,., ,,.. (3 ), (7 ), (4 ). 3. ( ),. :,, VnR(Virtual and Real worlds). VnR,.,, (TTA, 2010). (Mills & Noyes, 1999; Greenhalhg & Benford, 1999; Jin et al., 2001). (presence). (Mania & Chalmers, 2001). (Sanchez-Vives & Slater, 2005; Sas, 2004). (Lee et al., 2006).. (Mixed Reality) (Augmented Reality) (Azuma, 1997; Kishino & Milgram, 1994). (Illusion)

3 (Lessiter et al., 2001).. (Heiling, 1992; Hong, 2000). (Barfield & Hendrix, 1995; Hendrix & Barfield, 1996a). (Handrix & Barfield, 1996b). (The haptic : i.e., touch) (The sensations of the skin) (Kay et al., 1998; Ogi & hirose, 1996).. Fisher & Tazelaar(1991) Heim(1993) Steuer(1992) (Presence) (Immersion) (Interactivity) 3 (Lisewski, 2006). Lessiter (2000, 2001) ITC-SOPI(Independent Television Commission Sense of Presence Inventory). ITC-SOPI (Spatial Pressence), (Engagement), (Ecological Validity) (Negative Effects). Witmer & Singer(1998) (PQ Item Analysis). Mahdjoubi & Wiltshire(2001) (Interest and Engagement), (Comprehension), (Representativeness), (Realism and Accuracy), (Visual Realism)....,. 2..,. (Lessiter 2001).,,.,,,. (texture), (number of polygons), (visual field of view), (refresh rate) (frame rate). (Barfield & Hendrix, 1995; Hendrix, 1996). (Gibbs et al., 1998).

4 (Heiling, 1992)..,,,,.. 3. Figure 1.. (factor analysis)., ,., 3 5 FGI(Focus Group Interview)., 100 3, Figure 1. Procedure for measuring virtual realization..,

5 3.3.,, ( 100, 100 ; ±3.95) ( / ) (Exploratory factor analysis). SPSS 12.0K. 17 (maximum liklihood estimation) (oblique rotaion). 200, (Confirmatory factor analysis). SPSS AMOS 18.0K, (hierarchical factor model) 3.,. 3.5.,.,.,, (Morton heilig, 1962).,., 3. 70%, ( 100, 100 ; ±3.30). 3 5.

6 RMSEA(Root Mean Square Error of Approximation). RMSEA , Table 1., 3., Table , (Visual Presence). 2, (Visual Immersion). 3 (Visual Interactivity). Table 1. Result of Exploratory factor analysis Factor Model x² df p RMSEA Table 2. Result of Exploratory factor analysis accordance with measurement items Factor Measurement items Q : Q : Q : Q : Q : Q : Q : Q : Q : Q : Q : Q : Q : Q : Table 3, TLI(Tucker Lewi Index) CFI(Comparative Fit Index) , 2.5. Hierarchical , Table 4 Table 5 3, 7,

7 Table 3. Result of Confirmatory factor analysis accordance with factor model Table 5. The determined measurement reverse items as result of confirmatory factor analysis Factor Model x² df CFI TLI RMSE A hierarchical Table 4. The determined measurement items as result of No. confirmatory factor analysis Measurement items No Measurement reverse items How awkward did you feel somewhere in this virtual environment? How difficult did you immerse into this virtual environment? How awkward did you feel visual expression of this virtual environment? How awkward did you feel movements of objects in this virtual environment? 01 How much was the degree of realization in this virtual environments? How much did you feel the realistic degree of objects movements in this virtual environment? How much did you feel the natural degree of objects movements in virtual environment? 04 How natural was this virtual environment? How much was the degree of immersion in this virtual environment? How similar was this virtual environment compared with its corresponding real environment? How strongly did you feel the objects in this environment? How contact-able was the objects in this virtual environment? How much did you feel that this virtual environment is part of its corresponding real environment? How much was the degree of representative quality of this virtual environment? How much did you feel the degree of interaction-ability with this virtual environment? How frequently did you move against the change of this virtual environment? How much did you perceive feedbacks for your interactions in this virtual environment? 3. (visual presence) Figure 2, (visual immersion) Figure 3, (visual interactivity) Figure 4. (,, ). - U (Mann-Whitney U test). 1 (Bonfferroni crrection)., p = How much did you feel that someone gazed at you in this virtual environment?

8 Figure 2. Subjective evaluation results for Visual Presence Figure 3. Subjective evaluation results for Visual Immersion Figure 4. Subjective evaluation results for Visual Interactivity 6.,.. (,, ),., 18 ( 3, 7, 4, 4 ). 3 ( )..,.. (texture), (number of polygons), (visual field of view), (refresh rate) (frame rate),.., (, ).,.

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10 virtual Environment, 7(3), : : :