\section{Conclusion}
\label{conclusion}

%Summary of the research problem, method, main findings, and implications.

We designed and implemented a system for rendering virtual haptic grating textures on a real tangible surface touched directly with the fingertip, using a wearable vibrotactile voice-coil device mounted on the middle phalanx of the finger. %, and allowing free explorative movements of the hand on the surface.
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This tactile feedback was integrated with an immersive visual virtual environment, using an OST-AR headset, to provide users with a coherent multimodal visuo-haptic augmentation of the real environment, that can be switched between an AR and a VR view.
%
We investigated then with a psychophysical user study the effect of visual rendering of the hand and its environment on the roughness perception of the designed tactile texture augmentations: without visual augmentation (\level{Real} rendering), in AR with a realistic virtual hand superimposed on the real hand (\level{Mixed} rendering), and in VR with the same virtual hand as an avatar (\level{Virtual} rendering).
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%Only the amplitude $A$ varied between the reference and comparison textures to create the different levels of roughness.
%
%Participants were not informed there was a reference and comparison textures, and
No texture was represented visually, to avoid any influence on the perception \cite{bergmanntiest2007haptic,yanagisawa2015effects}.