\section{Making a movie}
Let's take the 2nd movie below as an example of how the movies and the
related data products come about. 
        Note, that I will explain
        \hyperref
        {later}
        {in section }
        {}
        {movie02}
        what these files show.
\begin{enumerate}
\item	The IDL procedure 
	\linkf{{\tt mf\_02}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/idl/mf\_02.pro}
	calls 
	\link{{\tt script1}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/idl/script1.pro}
	101 times, each time changing one or more parameters;
	in this case $a/M$ is changed from 0.00 to 1.00.
	It writes 101 Inventor files, called 
	\link{{\tt frame000.iv}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame000.iv.gz},
	\ldots,
	\link{{\tt frame100.iv}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame100.iv.gz}.

\item	\linkf{Explorer}
	{http://www.nag.co.uk/Welcome\_IEC.html}
	is used to make 101 RGB images from the 101 Inventor 3D scenes.
	In turn, the Inventor files are read using the module
	{\tt ReadGeom}, rendered using the module {\tt Render},
	and written as an RGB image using the module {\tt WriteImg}.
	A {\tt For} module and two {\tt AnimFile} modules are used to 
	automate the process for all 101 frames.
	Before the run is started, the user interactively positiones 
	the first (or last)
	3D scene in {\tt Render}, finding a nice view / camera setting.
	This is used for all 101 files, then.
	The {\tt Render} window size is chosen to be 448 pixels by
	448 pixels, i.e.\ multiple of 16.
	The technical details are described further in 
	\hyperref
	{an appendix}
	{appendix }
	{}
	{explorer_movie}.

\item	The IDL procedure
	\linkf{{\tt mf\_02\_an}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/idl/mf\_02\_an.pro}
	is used to annotate the images --
	in this case, the text
	``a/M=0.00'', \ldots, ``a/M=1.00'' is overlayed in the lower right
	corner of the images.
	It calls \link{{\tt annotation\_image}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/idl/annotation\_image.pro}
	101 times, and every time the temporary annotation image is
	added to the ``real'' image (which Explorer produced) using the
	\sgin{} UNIX command {\tt add}.
	{\tt add} has the side effect of transforming the uncompressed
	RGB files that Explorer produced to RLE compressed RGB files,
	reducing the file size by a factor of $\sim$ 4,
	from 600 kbyte ($448^2\cdot3$ byte) to 110--160 kbyte.

\item	The \sgin{} UNIX command {\tt dmconvert} is used to make
	an Animation coded QuickTime movie,
	\linkf{{\tt movie02.qt}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/movie02.qt},
	and an MPEG movie,
	\linkf{{\tt movie02.mpeg}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/movie02.mpeg}.
	This is done by 
	\linkf{this}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/Make\_movies1}
	C-shell script.

\item	The \sgin{} UNIX command {\tt togif} is used to make
	101 GIF images, 
	\link{{\tt frame000.gif}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame000.gif},
	\ldots,
	\link{{\tt frame100.gif}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame100.gif}
	from the RGB images.
	The size of the GIF files is only 23 kbyte.
	The public domain UNIX program
	\linkf{GIFMerge}
	{http://www.iis.ee.ethz.ch/\~{}kiwi/GIFMerge/}
	is used to make an animated GIF, 
	\linkf{{\tt movie02\_anim.gif}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/movie02\_anim.gif}.
	This is done by 
	\linkf{this}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/Make\_movies2}
	C-shell script.

\item	The UNIX program 
	{\tt xv}
	is used to make a PostScript file,
	\linkf{{\tt frame000.ps}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame000.ps}
	from the first RGB file. The black background color is changed to 
	white, and the yellow annotation text color changed to black,
	well suited for printing.

\item	All the RGB files are deleted.

\item	The \sgin{} UNIX command {\tt ivToVRML} 
	(see \linkf{here}
	{http://webspace.sgi.com/tools/})
	is used to make
	101 VRML files,
	\link{{\tt frame000.wrl}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame000.wrl.gz},
	\ldots,
	\link{{\tt frame100.wrl}}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/frame100.wrl.gz}
	from the 101 Inventor files.
	This is done by 
	\linkf{this}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/Make\_VRML}
	C-shell script.

\item	The Inventor and VRML files are compressed using
	{\tt gzip}, reducing the file size by a factor of $\sim$ 5.

\item	All the visualization files in the
	\linkf{directory in question}
	{http://www.astro.ku.dk/\~{}milvang/RelViz/Anim/02/}
	take up about 12 Mbyte of disk space.
\end{enumerate}
