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NAME

       r.out.mat  - Exports a GRASS raster to a binary MAT-File.

KEYWORDS

       raster, export

SYNOPSIS

       r.out.mat
       r.out.mat help
       r.out.mat [-v] input=name output=string  [--verbose]  [--quiet]

   Flags:
       -v
           Verbose mode

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input raster map

       output=string
           Name for the output binary MAT-File

DESCRIPTION

       r.out.mat  will export a GRASS raster map to a MAT-File which can be loaded into Matlab or
       Octave for plotting or further analysis.  Attributes such as map  title  and  bounds  will
       also be exported into additional array variables.
       Specifically, the following array variables are created:
        map_data
        map_name
        map_title (if it exists)
        map_northern_edge
        map_southern_edge
        map_eastern_edge
        map_western_edge
       In  addition,  r.out.mat  makes  for  a  nice  binary  container  format  for transferring
       georeferenced maps around, even if you don't use Matlab or Octave.

NOTES

       r.out.mat exports a Version 4 MAT-File. These files should  successfully  load  into  more
       modern versions of Matlab and Octave without any problems.
       Everything  should  be  Endian  safe,  so  the resultant file can be simply copied between
       different system architectures without binary translation.
       As there is no IEEE value for NaN  for  integer  maps,  GRASS's  null  value  is  used  to
       represent  it  within these maps. You'll have to do something like this to clean them once
       the map is loaded into Matlab:
       Null values in maps containing either floating point or double-precision
       floating point data should translate into <tt>NaN values as expected.
       r.out.mat must load the entire map into memory before writing,
       therefore it might have problems with huge maps.
       (a 3000x4000 DCELL map uses about 100mb RAM)
       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 the map's resolution information:

           [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

EXAMPLE

       In Matlab, plot with either:
       imagesc(map_data), axis equal, axis tight, colorbar
        or
       contourf(map_data, 24), axis ij, axis equal, axis tight, colorbar

TODO

       Add support for exporting map history, category information, color map, etc.
       Option to export as a version 5 MAT-File, with map and support  information  stored  in  a
       single structured array.

SEE ALSO

        r.in.mat
       r.out.bin
       r.null
       The Octave project

AUTHOR

       Hamish Bowman

       Department of Marine Science
       University of Otago
       New Zealand

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

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