\section{Conclusion}
\label{conclusion}

In this chapter, we designed and implemented a system for rendering virtual visuo-haptic textures that augment a real surface.
Directly touched with the fingertip, the perceived roughness of the surface can be increased using a wearable vibrotactile voice-coil device mounted on the middle phalanx of the finger.
We adapted the 1D sinusoidal grating rendering method, common in the literature but not yet integrated in a direct touch context, for use with vision-based pose estimation of the finger and paired it with an \OST-\AR headset.

Our wearable visuo-haptic augmentation system enable any real surface to be augmented with a minimal setup.
It also allows a free exploration of the textures, as if they were real (\secref[related_work]{ar_presence}), by letting the user view them from different poses and touch them with the bare finger without constraints on hand movements.
The visual latency we measured is typical of \AR systems, and the haptic latency is below the perceptual detection threshold for vibrotactile rendering.

This system forms the basis of the apparatus for the user studies presented in the next two chapters, which evaluate the user perception of these visuo-haptic texture augmentations.