Ubuntu Manpage: r.in.mat - Imports a binary MAT-File(v4) to a GRASS raster.

NAME

       r.in.mat  - Imports a binary MAT-File(v4) to a GRASS raster.

KEYWORDS

       raster, import

SYNOPSIS

       r.in.mat
       r.in.mat help
       r.in.mat [-v] input=string  [output=string]   [--overwrite]  [--verbose]  [--quiet]

   Flags:
       -v
           Verbose mode

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=string
           Name of an existing MAT-File(v4)

       output=string
           Name for the output raster map (override)

DESCRIPTION

       r.in.mat  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.
       Specifically, the following array variables will be read:
        map_data
        map_name
        map_title
        map_northern_edge
        map_southern_edge
        map_eastern_edge
        map_western_edge
       Any other variables in the MAT-file will be simply skipped over.
       The  'map_name' 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  output=  option,  the  raster
       map's  name  will  be  set  to  "MatFile" or the name specified respectively.  (maximum 64
       characters; normal GRASS naming rules apply)
       The 'map_title' variable is optional, the map's title is set if it exists.
       The 'map_northern_edge' 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.

NOTES

r.in.mat imports a Version 4 MAT-File. These files can be successfully created with more
modern versions of Matlab and Octave (see "EXAMPLES" below).
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).
As there is no IEEE value for NaN 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 NaN
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:
r.mapcalc int_map="int(MATFile_map)"
NaN values in either floating point or double-precision floating point matrices should
translate into null values as expected.
r.in.mat must load the entire map array into memory before writing, therefore it might
have problems with huge arrays. (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 and check the map's resolution information will be correct:
[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

Remember Matlab arrays are referenced as (row,column), i.e. (y,x).
In addition, r.in.mat and r.out.mat make for a nice binary container format for
transferring georeferenced maps around, even if you don't use Matlab or Octave.

EXAMPLES

       In Matlab, save with:
       save filename.mat map_* -v4
        In Octave, save with:
       save -mat4-binary filename.mat map_*

TODO

       Robust  support for mixed-Endian importation.  (This is a work in progress, please help by
       reporting any failures to the GRASS bug tracking system; you will need to  login  with  an
       OSGeo Userid)
       Add  support  for  importing  map  history, category information, color map, etc.  if they
       exist.
       Option to import a version 5 MAT-File, with map and support information stored in a single
       structured array.

BUGS

       If you encounter any problems, please contact the GRASS Development Team.

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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