1r.resamp.interp(1) GRASS GIS User's Manual r.resamp.interp(1)
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6 r.resamp.interp - Resamples raster map to a finer grid using interpo‐
7 lation.
8
10 raster, resample, interpolation, nearest neighbor, bilinear, bicubic,
11 lanczos, parallel
12
14 r.resamp.interp
15 r.resamp.interp --help
16 r.resamp.interp input=name output=name [method=string] [nprocs=inte‐
17 ger] [memory=memory in MB] [--overwrite] [--help] [--verbose]
18 [--quiet] [--ui]
19 Flags:
21 --overwrite
22 Allow output files to overwrite existing files
23 --help
25 Print usage summary
26 --verbose
28 Verbose module output
29 --quiet
31 Quiet module output
32 --ui
34 Force launching GUI dialog
35 Parameters:
37 input=name [required]
38 Name of input raster map
39 output=name [required]
41 Name for output raster map
42 method=string
44 Sampling interpolation method
45 Options: nearest, bilinear, bicubic, lanczos
46 Default: bilinear
47 nearest: Nearest-neighbor interpolation
48 bilinear: Bilinear interpolation
49 bicubic: Bicubic interpolation
50 nprocs=integer
52 Number of threads for parallel computing
53 Default: 1
54 memory=memory in MB
56 Maximum memory to be used (in MB)
57 Cache size for raster rows
58 Default: 300
59
61 r.resamp.interp resamples an input raster map by interpolating between
62 the neighboring cells via a selectable resampling algorithm. All cells
63 present in the neighborhood of the input raster cell must be non-null
64 to generate a non-null cell in the output raster map. A choice of four
65 interpolation methods is available; each uses the weighted values of a
66 different number of adjacent cells in the input map to determine the
67 value of each cell in the output map as follows:
68 • nearest neighbour (1 cell)
70 • bilinear (4 cells)
72 • bicubic (16 cells)
74 • lanczos (25 cells)
76 This module is intended for reinterpolation of continuous data to a
78 different resolution rather than for interpolation from scattered data
79 (use the v.surf.* modules for that purpose).
80
82 Resampling modules (r.resample, r.resamp.stats, r.resamp.interp, r.re‐
83 samp.rst) resample the map to match the current region settings.
84 Note that for bilinear, bicubic and lanczos interpolation, cells of the
86 output raster that cannot be bounded by the appropriate number of input
87 cell centers are set to NULL (NULL propagation). This could occur due
88 to the input cells being outside the current region, being NULL or
89 MASKed.
90 For longitude-latitude locations, the interpolation algorithm is based
92 on degree fractions, not on the absolute distances between cell cen‐
93 ters. Any attempt to implement the latter would violate the integrity
94 of the interpolation method.
95 PERFORMANCE
97 By specifying the number of parallel processes with nprocs option,
98 r.resamp.interp can run significantly faster, see benchmarks below.
99 Figure: Benchmark shows execution time for different number of cells.
100 See benchmark scripts in source code.
101 To reduce the memory requirements to minimum, set option memory to
103 zero. To take advantage of the parallelization, GRASS GIS needs to
104 compiled with OpenMP enabled.
105
107 Resample elevation raster map to a higher resolution (from 500m to
108 250m; North Carolina sample dataset):
109 g.region raster=elev_state_500m -p
110 g.region res=250 -ap
111 r.resamp.interp input=elev_state_500m output=elev_state_250m \
112 method=bilinear
113 Original 500m resolution elevation map
114 Resampled (bilinear) 250m resolution elevation map
116
118 g.region, r.resample, r.resamp.filter, r.resamp.rst, r.resamp.stats
119 Overview: Interpolation and Resampling in GRASS GIS
121
123 Glynn Clements
124
126 Available at: r.resamp.interp source code (history)
127 Accessed: Saturday Oct 28 18:17:54 2023
129 Main index | Raster index | Topics index | Keywords index | Graphical
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132 © 2003-2023 GRASS Development Team, GRASS GIS 8.3.1 Reference Manual
134GRASS 8.3.1 r.resamp.interp(1)