r.out.mat(1)

1r.out.mat(1)                  Grass User's Manual                 r.out.mat(1)
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NAME

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

9       raster
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SYNOPSIS

12       r.out.mat
13       r.out.mat help
14       r.out.mat [-v] input=string output=string
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16   Flags:
17       -v  Verbose mode
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19   Parameters:
20       input=string
21           Name of an existing raster map
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23       output=string
24           Name for the output binary MAT-File
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DESCRIPTION

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

51       r.out.mat exports a Version 4 MAT-File. These files should successfully
52       load  into  more modern versions of Matlab and Octave without any prob‐
53       lems.
54       Everything should be Endian safe, so the resultant file can  be  simply
55       copied  between  different system architectures without binary transla‐
56       tion.
57       As there is no IEEE value for NaN for integer maps, GRASS's null  value
58       is  used to represent it within these maps. You'll have to do something
59       like this to clean them once the map is loaded into Matlab:
60       Null values in maps containing either floating point  or  double-preci‐
61       sion
62       floating point data should translate into <tt>NaN values as expected.
63       r.out.mat must load the entire map into memory before writing,
64       therefore it might have problems with huge maps.
65       (a 3000x4000 DCELL map uses about 100mb RAM)
66       GRASS  defines  its map bounds at the outer-edge of the bounding cells,
67       not at
68       the coordinates of their centroids. Thus, the following Matlab commands
69       may
70       be used to determine the map's resolution information:
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72           [rows cols] = size(map_data)
73           x_range = map_eastern_edge - map_western_edge
74           y_range = map_northern_edge - map_southern_edge
75           ns_res = y_range/rows
76           ew_res = x_range/cols
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EXAMPLE

80       In Matlab, plot with either:
81       imagesc(map_data), axis equal, axis tight, colorbar
82        or
83       contourf(map_data, 24), axis ij, axis equal, axis tight, colorbar
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TODO

87       Add support for exporting map history, category information, color map,
88       etc.
89       Option to export as a version 5 MAT-File, with map and support informa‐
90       tion stored in a single structured array.
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AUTHOR

99       Hamish Bowman
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101       Department of Marine Science
102       University of Otago
103       New Zealand
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105       Last changed: $Date: 2005/12/12 14:53:40 $
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107       Full index
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111GRASS 6.2.2                                                       r.out.mat(1)