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