r.resamp.interpgrass - Online in the Cloud

PROGRAM:

NAME

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

KEYWORDS

raster, resample, interpolation

SYNOPSIS

r.resamp.interp
r.resamp.interp --help
r.resamp.interp input=name output=name [method=string] [--overwrite] [--help]
[--verbose] [--quiet] [--ui]

Flags:
--overwrite
Allow output files to overwrite existing files

--help
Print usage summary

--verbose
Verbose module output

--quiet
Quiet module output

--ui
Force launching GUI dialog

Parameters:
input=name [required]
Name of input raster map

output=name [required]
Name for output raster map

method=string
Sampling interpolation method
Options: nearest, bilinear, bicubic, lanczos
Default: bilinear
nearest: Nearest-neighbor interpolation
bilinear: Bilinear interpolation
bicubic: Bicubic interpolation

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 four 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)

· lanczos (25 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, bicubic and lanczos 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 raster=elev_state_500m -p
g.region res=250 -ap
r.resamp.interp input=elev_state_500m output=elev_state_250m \
method=bilinear
Original 500m resolution elevation map

Resampled (bilinear) 250m resolution elevation map

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