\section{Conclusion\label{bi:conclusion}}

In this chapter, we have described an interface that allows a user to navigate in a scene that is being streamed.
We identified and addressed the problems linked to the dynamics of both the user behaviour and the 3D content.

\begin{itemize}
    \item Navigating in a 3D scene can be complex, due to the many degrees of freedom, and tweaking the interface can increase the user's Quality of Experience.
    \item Adding bookmarks to the interface increases the quality of experience of the users and makes them visiting more data in the same amount of time.
    \item This increase in speed of navigation has a negative impact on the quality of service of the system.
    \item Having bookmarks in the scene biases the users navigation and makes the navigation more predictable: it is possible to link data utility to bookmarks in order to benefit from this predictability.
\end{itemize}

However, the system described in this chapter has some drawbacks and fails to answer the problems we mentioned in Section~\ref{i:challenges}, and all these problems come from the fact that \textbf{the content preparation is inexistent}.
The server knows all the data and simply determines what the client needs, it prepares the content and builds chunks on the go.
Thus, the server has to keep track of what the client already has (which will eat memory) and has to compute what should be sent next (which will eat CPU). The scalability of such a server is therefore inexistent.
Furthermore, we only considered geometry streaming: materials and textures are downloaded before the streaming starts, which causes great latency at the start of the streaming and harms the quality of experience.

After learning these lessons, we describe, in the next chapter, what is possible to do in order to alleviate these issues.
We show how the standard for video steaming, DASH, teaches us to prepare 3D content in order to remove all server side computations, to elaborate great streaming policies, and to support both geometry and texture chunks.
