1i.pca(1)                      Grass User's Manual                     i.pca(1)
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NAME

6       i.pca  - Principal components analysis (pca) program for image process‐
7       ing.
8

KEYWORDS

10       imagery
11

SYNOPSIS

13       i.pca
14       i.pca help
15       i.pca   input=string[,string,...]   output=string     [rescale=min,max]
16       [--overwrite]
17
18   Flags:
19       --overwrite
20
21   Parameters:
22       input=string[,string,...]
23           input layer name
24
25       output=string
26           output layer name
27
28       rescale=min,max
29           Rescaling range output (For no rescaling use 0,0) Default: 0,255
30

DESCRIPTION

32       i.pca is an image processing program based on the algorithm provided by
33       Vali (1990), that processes n (2 >= n) input raster map layers and pro‐
34       duces n output raster map layers containing the principal components of
35       the input data in decreasing order of variance ("contrast").  The  out‐
36       put  raster map layers are assigned names with .1, .2, ... .n suffixes.
37       The  current  geographic  region  definition  and  mask  settings   are
38       respected  when  reading  the input raster map layers. When the rescale
39       option is used, the output files are rescaled to fit the min,max range.
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OPTIONS

42   Parameters:
43       input=name,name[,name,name,...]
44              Name of two or more input raster map layers.
45
46       output=name
47              The output raster map layer name to which  suffixes  are  added.
48              Each  output  raster  map  layer is assigned this user-specified
49              name with a numerical (.1, .2, ...
50
51       rescale=min,max
52              The  optional  output  category  range.  (Default:   0,255)   If
53              rescale=0,0,  no rescaling is performed on output files.
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NOTES

56       Richards  (1986)  gives  a good example of the application of principal
57       components analysis (pca) to a time  series  of  LANDSAT  images  of  a
58       burned region in Australia.
59

SEE ALSO

61       Richards, John A., Remote Sensing Digital Image Analysis, Springer-Ver‐
62       lag, 1986.
63
64       Vali, Ali R., Personal communication, Space Research Center, University
65       of Texas, Austin, 1990.
66
67       i.cca
68       i.class
69       i.fft
70       i.ifft
71       m.eigensystem
72       r.covar
73       r.mapcalc
74

AUTHOR

76       David Satnik, GIS Laboratory
77
78       Major modifications for GRASS 4.1 were made by
79       Olga Waupotitsch and Michael Shapiro, U.S.Army Construction Engineering
80       Research Laboratory
81
82       Last changed: $Date: 2003/04/17 14:50:03 $
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84       Full index
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88GRASS 6.2.2                                                           i.pca(1)