32 lines
3.3 KiB
TeX
32 lines
3.3 KiB
TeX
\section{Introduction}
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\label{intro}
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In the previous chapter, we presented a system for augmenting the visuo-haptic texture perception of real surfaces directly touched with the finger, using wearable vibrotactile haptics and an \OST-\AR headset.
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In this chapter and the next one, we evaluate the user's perception of such wearable haptic texture augmentation under different visual rendering conditions.
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Most of the haptic augmentations of real surfaces using with wearable haptic devices, including roughness of textures (\secref[related_work]{texture_rendering}), have been studied without a visual feedback, and none have considered the influence of the visual rendering on their perception or integrated them in \AR and \VR (\secref[related_work]{texture_rendering}).
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Still, it is known that the visual rendering of an object can influence the perception of its haptic properties (\secref[related_work]{visual_haptic_influence}), and that the perception of same haptic force-feedback or vibrotactile rendering can differ between \AR and \VR, probably due to difference in perceived simultaneity between visual and haptic stimuli (\secref[related_work]{ar_vr_haptic}).
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In \AR, the user can see their own hand touching, the haptic device worn, and the \RE, while in \VR they are hidden by the \VE.
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In this chapter, we investigate the \textbf{role of the visual feedback of the virtual hand and of the environment (real or virtual) on the perception of a real surface whose haptic roughness is augmented} with wearable vibrotactile haptics. %voice-coil device worn on the finger.
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To do so, we used the visuo-haptic system presented in \chapref{vhar_system} to render virtual vibrotactile patterned textures (\secref[related_work]{texture_rendering}) to augment the real surface being touched. % touched by the finger.% that can be directly touched with the bare finger.
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We evaluated, in \textbf{user study with psychophysical methods and extensive questionnaire}, the perceived roughness augmentation in three visual rendering conditions: \textbf{(1) without visual augmentation}, in \textbf{(2) \OST-\AR with a realistic virtual hand} rendering, and in \textbf{(3) \VR with the same virtual hand}.
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To control for the influence of the visual rendering, the real surface was not visually augmented and stayed the same in all conditions.
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\noindentskip The contributions of this chapter are:
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\begin{itemize}
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\item A psychophysical user study with 20 participants to evaluate the effect of visual hand rendering in \OST-\AR or \VR on the perception of haptic roughness texture augmentations, using wearable vibrotactile haptics.
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\item A discussion and recommendations on the integration of wearable haptic augmentations in direct touch context with \AR and \VR.
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\end{itemize}
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\noindentskip In the next sections, we first describe the experimental design and apparatus of the user study.
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We then present the results obtained, discuss them, and outline recommendations for future \AR/\VR works using wearable haptic augmentations.
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\smallskip
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\fig[0.55]{teaser/teaser2}{
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Vibrotactile textures were rendered in real time on a real surface using a wearable vibrotactile device worn on the finger.
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}[
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Participants explored this haptic roughness augmentation with (\level{Real}) their real hand alone, (\level{Mixed}) a realistic virtual hand overlay in \AR, and (\level{Virtual}) the same virtual hand in \VR.
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]
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