NAME

       r.resamp.interp  - Resamples raster map layers to a finer grid using interpolation.

KEYWORDS

       raster, resample

SYNOPSIS

       r.resamp.interp
       r.resamp.interp help
       r.resamp.interp   input=name  output=name   [method=string]    [--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

       method=string
           Interpolation method
           Options: nearest,bilinear,bicubic
           Default: bilinear

DESCRIPTION

       r.resamp.interp resamples an input raster map by  interpolating  between  the  neighboring
       cells  via a selectable resampling algorithm. All cells present in the neighborhood of the
       input raster cell must be non-null to generate a non-null cell in the output raster map. A
       choice  of  three  interpolation  methods is available; each uses the weighted values of a
       different number of adjacent cells in the input map to determine the value of each cell in
       the output map as follows:

                     nearest neighbour (1 cell)

                     bilinear (4 cells)

                     bicubic (16 cells)
       This  module  is intended for reinterpolation of continuous data to a different resolution
       rather than for interpolation from scattered data  (use  the  v.surf.*  modules  for  that
       purpose).

NOTES

       Resampling  modules  (r.resample,  r.resamp.stats, r.resamp.interp, r.resamp.rst) resample
       the map to match the current region settings.

       Note that for bilinear and bicubic interpolation, cells of the output raster  that  cannot
       be  bounded  by  the  appropriate  number  of  input  cell  centers  are set to NULL (NULL
       propagation). This could occur due to the input cells being outside  the  current  region,
       being NULL or MASKed.

       For   longitude-latitude  locations,  the  interpolation  algorithm  is  based  on  degree
       fractions, not on the absolute distances between cell centers.  Any attempt  to  implement
       the latter would violate the integrity of the interpolation method.

EXAMPLE

       Resample  elevation  raster  map to a higher resolution (from 500m to 250m; North Carolina
       sample dataset):
       g.region rast=elev_state_500m -p
       g.region res=250 -ap
       r.resamp.interp input=elev_state_500m output=elev_state_250m

SEE ALSO

       g.region, r.resample, r.resamp.rst r.resamp.stats

AUTHOR

       Glynn Clements

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

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       © 2003-2013 GRASS Development Team