\fresh{}

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

In this chapter, we have described a basic interface that allows a user to navigate in a scene that is being streamed.
It allowed us to understand the problems linked to the dynamicity 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 can have a drawback on the quality of service of the system.
    \item Having bookmarks in the scene biases the users nagivation and make them more predictible: it is then possible to precompute data from bookmarks in order to benefit from this predictability.
\end{itemize}

However, the system described in this chapter has some drawbacks and fails to answer some of the problems we mentioned in Section~\ref{i:challenges}.

\begin{itemize}
    \item \textbf{The content preparation and chunk utility is almost inexistant}: the server knows all the data and simply determines what the client needs, he prepares the content and builds chunk on the go. Furthermore, it has no support for material or textures: in our setup, they are downloaded before the streaming starts.
    \item \textbf{The streaming policy is basic}: the server traverses all the polygons and determines which polygons should be sent to the client.
    \item \textbf{The implementation has sloppy\todo{maybe \emph{sloppy} is too strong} performances}: since the content preparation and the streaming policy is made on the fly, 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 not possible. Moreover, no client performance has been taken into account since the client used in the user-study did not have to perform streaming.
\end{itemize}

After learning these lessons, we show, in the next chapter, what is possible to do in order to alleviate these issues.
