1r.surf.idw2(1) Grass User's Manual r.surf.idw2(1)
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6 r.surf.idw2 - Surface generation program.
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9 raster
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12 r.surf.idw2
13 r.surf.idw2 help
14 r.surf.idw2 input=name output=name [npoints=count] [--overwrite]
15 [--verbose] [--quiet]
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17 Flags:
18 --overwrite
19 Allow output files to overwrite existing files
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21 --verbose
22 Verbose module output
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24 --quiet
25 Quiet module output
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27 Parameters:
28 input=name
29 Name of input raster map
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31 output=name
32 Name for output raster map
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34 npoints=count
35 Number of interpolation points
36 Default: 12
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39 r.surf.idw2 fills a raster matrix with interpolated values generated
40 from a set of irregularly spaced data points using numerical approxima‐
41 tion (weighted averaging) techniques. The interpolated value of a cell
42 is determined by values of nearby data points and the distance of the
43 cell from those input points. In comparison with other methods, numer‐
44 ical approximation allows representation of more complex surfaces (par‐
45 ticularly those with anomalous features), restricts the spatial influ‐
46 ence of any errors, and generates the interpolated surface from the
47 data points. It is the most appropriate method to apply to most spa‐
48 tial data. The npoints parameter defines the number of points to use
49 for interpolation. The default is to use the 12 nearest points when
50 interpolating the value for a particular cell.
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53 The amount of memory used by this program is related to the number of
54 non-zero data values in the input map layer. If the input raster map
55 layer is very dense (i.e., contains many non-zero data points), the
56 program may not be able to get all the memory it needs from the system.
57 The time required to execute increases with the number of input data
58 points.
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60 If the user has a mask set, then interpolation is only done for those
61 cells that fall within the mask. However, all non-zero data points in
62 the input layer are used even if they fall outside the mask.
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64 This program does not work with latitude/longitude data bases. Another
65 surface generation program, named r.surf.idw, should be used with lati‐
66 tude/longitude data bases.
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68 The user should refer to the manual entries for
69 r.surf.idw
70 r.surf.contour
71 v.surf.rst
72 to compare this surface generation program with others available in
73 GRASS.
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76 r.surf.contour, r.surf.idw, r.surf.gauss, r.surf.fractal, r.surf.ran‐
77 dom, r.surf.idw2, v.surf.rst
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80 Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
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82 Last changed: $Date: 2006-04-13 21:01:38 +0200 (Thu, 13 Apr 2006) $
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84 Full index
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86 © 2003-2008 GRASS Development Team
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90GRASS 6.3.0 r.surf.idw2(1)