<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>GRASS GIS: r.in.mat</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<link rel="stylesheet" href="grassdocs.css" type="text/css">
</head>
<body bgcolor="white">
<img src="grass_logo.png" alt="GRASS logo"><hr align=center size=6 noshade>
<h2>NAME</h2>
<em><b>r.in.mat</b></em> - Imports a binary MAT-File(v4) to a GRASS raster.
<h2>KEYWORDS</h2>
raster
<h2>SYNOPSIS</h2>
<b>r.in.mat</b><br>
<b>r.in.mat help</b><br>
<b>r.in.mat</b> [-<b>v</b>] <b>input</b>=<em>string</em> [<b>output</b>=<em>string</em>] [--<b>overwrite</b>] [--<b>verbose</b>] [--<b>quiet</b>]
<h3>Flags:</h3>
<DL>
<DT><b>-v</b></DT>
<DD>Verbose mode</DD>
<DT><b>--overwrite</b></DT>
<DD>Allow output files to overwrite existing files</DD>
<DT><b>--verbose</b></DT>
<DD>Verbose module output</DD>
<DT><b>--quiet</b></DT>
<DD>Quiet module output</DD>
</DL>
<h3>Parameters:</h3>
<DL>
<DT><b>input</b>=<em>string</em></DT>
<DD>Name of an existing MAT-File(v4)</DD>
<DT><b>output</b>=<em>string</em></DT>
<DD>Name for the output raster map (override)</DD>
</DL>
<H2>DESCRIPTION</H2>
<EM>r.in.mat</EM> will import a GRASS raster map from a Version 4 MAT-File
which was created with Matlab or Octave.
Attributes such as map title and bounds will also be imported if they exist.
<BR>
<BR>
Specifically, the following array variables will be read:<BR>
<ul>
<li><b> map_data</b>
<li><b> map_name</b>
<li><b> map_title</b>
<li><b> map_northern_edge</b>
<li><b> map_southern_edge</b>
<li><b> map_eastern_edge</b>
<li><b> map_western_edge</b>
</ul>
Any other variables in the MAT-file will be simply skipped over.<BR>
<BR>
The '<b>map_name</b>' variable is optional, if it exists, and is valid, the
new map will be thus named. If it doesn't exist or a name is specified with
the <b>output=</b> option, the raster map's name will be set to
"<tt>MatFile</tt>" or the name specified respectively.
(maximum 64 characters; normal GRASS naming rules apply)
<BR>
<BR>
The '<b>map_title</b>' variable is optional, the map's title is set if it
exists.
<BR>
<BR>
The '<b>map_northern_edge</b>' and like variables are mandatory unless the
user is importing to a "XY" non-georeferenced location
(e.g. imagery data). Latitude and longitude values should be in decimal form.
<H2>NOTES</H2>
<EM>r.in.mat</EM> imports a Version 4 MAT-File. These files can be
successfully created with more modern versions of Matlab and Octave
(see "EXAMPLES" below).<BR><BR>
Everything should be Endian safe, so the file to be imported can be simply
copied between different system architectures without binary translation
(caveat: see "TODO" below).<BR><BR>
As there is no IEEE value for <tt>NaN</tt> in integer arrays, GRASS's null
value may be used to represent it within these maps. Usually Matlab will save
any integer based matrix with <tt>NaN</tt> values as a double-precision
floating point array, so this usually isn't an issue. To save space, once the
map is loaded into GRASS you can convert it back to an integer map with the
following command:
<div class="code"><pre>
r.mapcalc int_map="int(MATFile_map)"
</pre></div>
<tt>NaN</tt> values in either floating point or double-precision floating point
matrices should translate into null values as expected.<BR><BR>
<EM>r.in.mat</EM> must load the entire map array into memory before writing,
therefore it might have problems with <i>huge</i> arrays.
(a 3000x4000 DCELL map uses about 100mb RAM)<BR><BR>
GRASS defines its map bounds at the outer-edge of the bounding cells, not at
the coordinates of their centroids. Thus, the following Matlab commands may
be used to determine and check the map's resolution information will be correct:
<div class="code"><pre>
[rows cols] = size(map_data)
x_range = map_eastern_edge - map_western_edge
y_range = map_northern_edge - map_southern_edge
ns_res = y_range/rows
ew_res = x_range/cols
</pre></div>
<BR>
Remember Matlab arrays are referenced as <tt>(row,column)</tt>,
i.e. <tt>(y,x)</tt>.
<BR><BR>
In addition, <EM>r.in.mat</EM> and <EM>r.out.mat</EM> make for a nice
binary container format for transferring georeferenced maps around,
even if you don't use Matlab or Octave.
<H2>EXAMPLES</H2>
In Matlab, save with:
<div class="code"><pre>
save filename.mat map_* -v4
</pre></div>
In Octave, save with:
<div class="code"><pre>
save -mat4-binary filename.mat map_*
</pre></div>
<BR>
<H2>TODO</H2>
Robust support for mixed-Endian importation.
<i>(This is a work in progress, please help by reporting any failures to the
<a href="http://grass.itc.it/bugtracking/bugreport.html">
GRASS bug tracking system</a>)</i>
<BR>
Add support for importing map history, category information, color map, etc.
if they exist.
<BR>
Option to import a version 5 MAT-File, with map and support information
stored in a single structured array.
<H2>BUGS</H2>
If you encounter any problems, please contact the GRASS Development Team.
<H2>SEE ALSO</H2>
<i>
<a href="r.out.mat.html">r.out.mat</a>,
<a href="r.in.ascii.html">r.in.ascii</a>,
<a href="r.in.bin.html">r.in.bin</a>,
<a href="r.mapcalc.html">r.mapcalc</a>,
<a href="r.null.html">r.null</a>.<P>
The <a href="http://www.octave.org">Octave</a> project
</i>
<H2>AUTHOR</H2>
Hamish Bowman<BR> <i>
Department of Marine Science<BR>
University of Otago<BR>
New Zealand</i><BR>
<BR>
<p><i>Last changed: $Date: 2006-04-21 11:06:24 +0200 (Fri, 21 Apr 2006) $</i>
<HR>
<P><a href="index.html">Main index</a> - <a href="raster.html">raster index</a> - <a href="full_index.html">Full index</a></P>
<P>© 2003-2008 <a href="http://grass.osgeo.org">GRASS Development Team</a></p>
</body>
</html>
