# Exploring the Effect of Virtual Environments on Passive
## 3 System Overview and Approach  
Figure 2 shows our system configuration and an example of passive haptic perception in an immersive virtual environment. A participant was seated in a chair in front of a desk, wearing a head-mounted display (HMD) to view the fully immersive space. The participant could interact with a virtual object such as a computer-generated cube. In our case, a tracking device consisting of optical marker sets was used for recognizing the participant's hand position and orientation. Moreover, a virtual hand in our virtual environment represented dynamic physical reaching from precise transformation (e.g., position and orientation) data from rigid-body marker sets attached on the participant's real hand. A precise tracking system with an error of less than 1 mm for the participant's hand interactions was used. Figure 2 also represents the real and virtual scenes used to evaluate passive haptic perception in our paper. The participants could not perceive the slight difference in virtual conditions compared to the real environment (e.g., the case with different reaching degrees of the virtual object). \begin{table}
\begin{tabular}{l l l} \hline \hline
**Issues** & **Problems** & **References** \\ \hline \multirow{4}{*}{Consistency in virtual environments} & Matching between a real object & [PERSON] et al. [3], [PERSON] et al. [9] \\  & and the related virtual object & [PERSON] et al. [3], [PERSON] et al. [9] \\ \cline{2-3}  & Consistency between shared & \\  & virtual environments & [PERSON] et al. [1] \\ \hline \multirow{2}{*}{Haptic devices and rendering} & Computing correct interaction & [PERSON] [7], [PERSON] et al. [16], \\  & forces & [PERSON] et al. [17], [PERSON] et al. [18] \\ \hline \multirow{2}{*}{Haptic retargeting} & Remapping techniques for & [PERSON] et al. [4], [PERSON] et al. \\  & reaching of the virtual hand & [5], [PERSON] et al. [20] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classification of issues and problems regarding passive haptic perception. Figure 2: An example of passive haptic perception, showing a situation where a participant touches a real object in the case of precise tracking, and the participant cannot perceive the difference in virtual conditions that slightly differed from the real environment. Table 2 shows our test conditions for the experiment aimed at determining the effects of passive haptic perception. We set test conditions to measure variables for transformation factors such as position, rotation, and scale. For example, when interacting with the virtual object in immersive environments, participants touched a real object via passive haptics under different test conditions, and they were asked to rate how they felt in the given situation. Through a preliminary experiment involving eight people, we set the limits of the value of our test conditions, and the value determined by all participants in the virtual environment to be different from the real environment was set as the boundary of the test conditions. In addition, we included situations where several-times errors occur, for example, the cases where participants cannot touch the physical prop due to a long distance during a given time. In our system, several steps were used to establish appropriate test conditions; in particular, the virtual hand was used to automatically operate visual feedback to calculate the distance depending on the tactile situation of the real object according to haptic retargeting [4]. Figure 3 shows our interaction process to evaluate the effect of passive haptic perception in immersive virtual environments. For example, to explore the participant's perception, the specific transformation condition was selected through three types of transformation conditions (adjustment of position, rotation, and scale parameters). The participant interacted with a real object for passive haptic feedback and a related virtual object as the corresponding counterpart. Then, the participant described the difference between the real and virtual objects.