rsaga.inverse.distance: Spatial Interpolation Methods

Description

Spatial interpolation of point data using inverse distance to a power (inverse distance weighting, IDW), nearest neighbors, or modified quadratic shephard.

Usage

rsaga.inverse.distance(
  in.shapefile,
  out.grid,
  field,
  power = 1,
  maxdist,
  nmax = 100,
  target,
  env = rsaga.env(),
  ...
)
rsaga.nearest.neighbour(
  in.shapefile,
  out.grid,
  field,
  target,
  env = rsaga.env(),
  ...
)
rsaga.modified.quadratic.shephard(
  in.shapefile,
  out.grid,
  field,
  quadratic.neighbors = 13,
  weighting.neighbors = 19,
  target,
  env = rsaga.env(),
  ...
)
rsaga.triangulation(
  in.shapefile,
  out.grid,
  field,
  target,
  env = rsaga.env(),
  ...
)

Arguments

in.shapefile: Input: point shapefile (default extension: .shp).
out.grid: Output: filename for interpolated grid (SAGA grid file). Existing files will be overwritten!
field: numeric or character: number or name of attribute in the shapefile's attribute table to be interpolated; the first attribute is represented by a zero.
power: numeric (>0): exponent used in inverse distance weighting (usually 1 or 2)
maxdist: numeric: maximum distance of points to be used for inverse distance interpolation (search radius); no search radius is applied when this argument is missing or equals Inf
nmax: Maximum number of nearest points to be used for interpolation; nmax=Inf is a valid value (no upper limit)
target: required argument of type list: parameters identifying the target area, e.g. the x/y extent and cellsize, or name of a reference grid; see rsaga.target().
env: RSAGA geoprocessing environment created by rsaga.env(), required because module(s) depend(s) on SAGA version
...: Optional arguments to be passed to rsaga.geoprocessor(), including the env RSAGA geoprocessing environment.
quadratic.neighbors: integer >=5; default 13.
weighting.neighbors: integer >=3; default 19.

Author

Alexander Brenning (R interface), Andre Ringeler and Olaf Conrad (SAGA modules)

Details

These functions use modules from the grid_gridding SAGA GIS library. They do not support SAGA GIS 2.0.4, which differs in some argument names and parameterizations. Target grid parameterization by grid file name currently doesn't work with SAGA GIS 2.1.0 Release Candidate 1 (see also rsaga.target()); stay tuned for future updates and fixes.

References