1\section{Other 3D tools in \RR\label{tools}}
2At the time of writing \sdd , the function \code{persp()} in the base
3package of \RR\ for three dimensional surface plots was available, but
4there was no way to generate 3D scatter plots in \RR\ itself.
5
6The data visualization system \emph{xgobi} (\cite{swayne98}) provides
7interactive visualization of multidimensional data, e.g. brush and spin,
8higher-dimensional rotation, grand tour, etc.  The \RR\ package
9\emph{xgobi} (\cite{swayne91}; we have to distinguish the visualization
10system and the package) provides an Interface to \emph{xgobi} and launches
11a \emph{xgobi} process appropriately.
12%%
13\emph{ggobi}\footnote{\url{http://www.ggobi.org}}
14(\cite{swayne02}) is the next edition of \emph{xgobi}.
15
16Analogously to \emph{xgobi} a \RR\ package \emph{Rggobi} (\cite{temple01})
17exists in the \emph{Omegahat} project\footnote{\url{http://www.omegahat.net}}
18(\cite{temple00}) that allows one to embed \emph{ggobi} within
19\RR\ and to both set and query the \emph{ggobi} contents.  All in all,
20\emph{ggobi} can be loaded dynamically into \RR\ (as well as into other
21software products, in principle), and \RR\ into \emph{ggobi}.  This
22provides interactive, direct manipulation, linked, high-dimensional
23graphics within \RR .
24
25The package \emph{rgl}\footnote{\url{http://wsopuppenkiste.wiso.uni-goettingen.de/~dadler/rgl/}}
26by \cite{AdlerNenadic2003} is a portable \RR\ programing interface to \emph{OpenGL}.
27Its features include, e.g., interactive viewpoint navigation,
28automatic data focus, up to 8 light sources, alpha-blending
29(transparency), and environmental effects like fogging.
30The package \emph{djmrgl}\footnote{This package was
31formerly called \emph{rgl}, similar to the other mentioned package
32by Daniel Adler and Oleg Nenadi\'{c}.
33\emph{djmrgl} is only available for the Windows operating system.}
34(\cite{murdoch}) also provides an \RR\ interface to \emph{OpenGL}.
35A huge collection of useful functions to generate,
36manipulate and interactively rotate 3D objects is available.
37Efforts are under way to merge these two packages.
38
39The function \code{cloud} in the lattice package is a 3D scatter plot function that works in the
40\emph{lattice} (\cite{sarkar02}) (and \emph{grid} (\cite{murrell01}))
41environment of \RR .
42\emph{Lattice} is an implementation of \emph{Trellis Graphics}, which is a
43framework for data visualization developed at the Bell Labs by
44\citeN{becker96}, extending ideas presented in \citeN{cleveland}.
45
46