\chapter{Conclusion}
\mainlabel{conclusion}

\section*{Summary}

In this thesis, entitled \enquote{\ThesisTitle}, we presented our research on direct hand interaction with real and virtual everyday objects, visually and haptically augmented using immersive \AR and wearable haptic devices.

\noindentskip \partref{manipulation}

\noindentskip In \chapref{visual_hand}, we addressed the challenge manipulating \VOs directly with the hand by providing visual renderings as hand augmentations.
Seen as an overlay on the user's hand, such visual hand rendering provide feedback on the hand tracking and the interaction with \VOs.
We compared the six commonly used renderings in the \AR litterature in a user study with 24 participants, where we evaluated their effect on the user performance and experience in two representative manipulation tasks.
Results showed that a visual hand rendering improved the user performance, perceived effectiveness and confidence, with a skeleton-like rendering being the most performant and effective.
This rendering provided a detailed view of the tracked phalanges while being thin enough not to hide the real hand.

\section*{Future Work}

The visuo-haptic renderings we presented and the user studies we conducted in this thesis have of course some limitations.
We present in this section some future work that could address these.

\subsection*{Visual Rendering of the Hand for Manipulating Virtual Objects in Augmented Reality}

\paragraph{Other AR Displays}

The visual hand renderings we evaluated were displayed on the Microsoft HoloLens~2, which is a common \OST-\AR headset.

\paragraph{More Ecological Conditions}

We evaluated the effect of the visual hand rendering with two manipulation tasks involving to place a virtual cube into a target volume either by pushing it on a table or by grasping it.
%While these tasks are fundamental and basics

These results have of course some limitations as they only address limited types of manipulation tasks and visual hand characteristics, evaluated in a specific \OST-\AR setup.
The two manipulation tasks were also limited to placing a virtual cube in predefined target volumes.
Testing a wider range of virtual objects and more ecological tasks \eg stacking, assembly, will ensure a greater applicability of the results obtained in this work, as well as considering bimanual manipulation.
Similarly, a broader experimental study might shed light on the role of gender and age, as our subject pool was not sufficiently diverse in this respect.
However, we believe that the results presented here provide a rather interesting overview of the most promising approaches in \AR manipulation.

\section*{Perspectives}

% systematic exploration of the parameter space of the haptic rendering to determine the most important parameters their influence on the perception
% measure the difference in sensitivity to the haptic feedback and how much it affects the perception of the object properties
% design, implement and validate procedures to automatically calibrate the haptic feedback to the user's perception in accordance to what it has been designed to represent
% + let user free to easily adjust (eg can't let adjust whole spectrum of vibrotactile, reduce to two or three dimensions with sliders using MDS)
