1r.fillnulls(1) Grass User's Manual r.fillnulls(1)
2
6 r.fillnulls - Fills no-data areas in raster maps using v.surf.rst
7 splines interpolation
8
10 raster, elevation, interpolation
11
13 r.fillnulls
14 r.fillnulls help
15 r.fillnulls input=string output=string [tension=float]
16 [smooth=float] [--overwrite] [--verbose] [--quiet]
17 Flags:
19 --overwrite
20 Allow output files to overwrite existing files
21 --verbose
23 Verbose module output
24 --quiet
26 Quiet module output
27 Parameters:
29 input=string
30 Raster map in which to fill nulls
31 output=string
33 Output raster map with nulls filled by interpolation from surround‐
34 ing values
35 tension=float
37 Spline tension parameter
38 Default: 40.
39 smooth=float
41 Spline smoothing parameter
42 Default: 0.1
43
45 r.fillnulls - Fills NULL (no data areas) in input map and stores
46 filled map to a new output map. The fill data are interpolated from the
47 no data area boundaries buffer using v.surf.rst spline interpolation.
48 (GRASS Shell Script)
49
51 Each area boundary buffer is set to three times the map resolution to
52 get nominally three points around the edge. This way the algorithm
53 interpolates into the hole with a trained slope and curvature at the
54 edges, in order to avoid that such a flat plane is generated in a hole.
55 During the interpolation following warning may occur:
57 Warning: strip exists with insufficient data
59 Warning: taking too long to find points for interpolation--please
60 change the region to area where your points are
61 This warning is generated if large data holes exist within the surface.
63 As the idea of r.fillnulls is to fill such holes, the user may ignore
64 the warning. The interpolation will be continued. However, the user may
65 pay attention to below notes.
66
68 The algorithm is based on v.surf.rst regularized splines with tension
69 interpolation module which interpolates the raster cell values for NULL
70 data areas from the boundary values of the NULL data area. An eventual
71 raster MASK is respected during the NULL data area(s) filling. The
72 interpolated values are patched into the NULL data area(s) of the input
73 map and saved into a new raster map.
74
76 Depending on the shape of the NULL data area(s) problems may occur due
77 to an insufficient number of input cell values for the interpolation
78 process. Most problems will occur if a NULL data area reaches a large
79 amount of the map boundary. The user will have to carefully check the
80 result using r.mapcalc (generating a difference map to the input map)
81 and/or d.what.rast to query individual cell values.
82
84 r.fill.dir, v.surf.rst
85 Mitas, L., Mitasova, H., 1999, Spatial Interpolation. In: P.Longley,
87 M.F. Goodchild, D.J. Maguire, D.W.Rhind (Eds.), Geographical Informa‐
88 tion Systems: Principles, Techniques, Management and Applications,
89 Wiley, pp.481-492
90 Mitasova H., Mitas L., Brown W.M., D.P. Gerdes, I. Kosinovsky,
92 Baker, T.1995, Modeling spatially and temporally distributed phenomena:
93 New methods and tools for GRASS GIS. International Journal of GIS, 9
94 (4), special issue on Integrating GIS and Environmental modeling,
95 433-446.
96 Mitasova H. and Mitas L. 1993: Interpolation by Regularized Spline
98 with Tension: I. Theory and Implementation, Mathematical Geology 25,
99 641-655.
100 Mitasova H. and Hofierka L. 1993: Interpolation by Regularized Spline
102 with Tension: II. Application to Terrain Modeling and Surface Geometry
103 Analysis, Mathematical Geology 25, 657-667.
104
106 r.fillnulls: Markus Neteler, University of Hannover
107 and authors of v.surf.rst
109 Improvement by Hamish Bowman, NZ
110 Last changed: $Date: 2006-04-20 23:31:24 +0200 (Thu, 20 Apr 2006) $
112 Full index
114 © 2003-2008 GRASS Development Team
116GRASS 6.3.0 r.fillnulls(1)