NAME¶
r.surf.idw2 - Surface generation program.
KEYWORDS¶
raster, interpolation
SYNOPSIS¶
r.surf.idw2
r.surf.idw2 help
r.surf.idw2 input=
name output=
name
[
npoints=
count] [--
overwrite] [--
verbose]
[--
quiet]
Flags:¶
- --overwrite
-
Allow output files to overwrite existing files
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- input=name
-
Name of input raster map
- output=name
-
Name for output raster map
- npoints=count
-
Number of interpolation points
Default: 12
DESCRIPTION¶
r.surf.idw2 fills a raster matrix with interpolated values generated from
a set of irregularly spaced data points using numerical approximation
(weighted averaging) techniques. The interpolated value of a cell is
determined by values of nearby data points and the distance of the cell from
those input points. In comparison with other methods, numerical approximation
allows representation of more complex surfaces (particularly those with
anomalous features), restricts the spatial influence of any errors, and
generates the interpolated surface from the data points. It is the most
appropriate method to apply to most spatial data. The
npoints parameter
defines the number of points to use for interpolation. The default is to use
the 12 nearest points when interpolating the value for a particular cell.
NOTES¶
The amount of memory used by this program is related to the number of non-zero
data values in the input map layer. If the input raster map layer is very
dense (i.e., contains many non-zero data points), the program may not be able
to get all the memory it needs from the system. The time required to execute
increases with the number of input data points.
If the user has a mask set, then interpolation is only done for those cells that
fall within the mask. However, all non-zero data points in the input layer are
used even if they fall outside the mask.
This program does not work with latitude/longitude data bases. Another surface
generation program, named
r.surf.idw, should be used with
latitude/longitude data bases.
The user should refer to the manual entries for
r.surf.idw
r.surf.contour
v.surf.rst
to compare this surface generation program with others available in GRASS.
SEE ALSO¶
r.surf.contour,
r.surf.idw,
r.surf.gauss,
r.surf.fractal,
r.surf.random,
r.surf.idw2,
v.surf.rst
AUTHOR¶
Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
Last changed: $Date: 2008-05-16 21:09:06 +0200 (Fri, 16 May 2008) $
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© 2003-2014 GRASS Development Team
