rsaga.ordinary.kriging {RSAGA} | R Documentation |
Perform ordinary kriging using a local search neighborhood (local ordinary kriging). Also supports block kriging.
rsaga.ordinary.kriging(in.shapefile, out.grid, out.variance.grid, field, model = c("spherical", "exponential", "gaussian"), nugget = 0, sill = 10, range = 100, log.transform = FALSE, maxdist = 1000, blocksize, nmin = 4, nmax = 20, target = rsaga.target(), ...)
in.shapefile |
Input: point shapefile
(default extension: .shp ). |
out.grid |
Output: filename for interpolated grid (SAGA grid file). Existing files will be overwritten! |
out.variance.grid |
Output (optional): SAGA grid for kriging variances |
field |
numeric(!): number (not name!) of attribute in the shapefile's attribute table to be interpolated; the first attribute is represented by a zero. |
model |
character: variogram model to be used;
defaults to "spherical" . |
nugget |
numeric (>=0): Nugget effect |
sill |
numeric (>=0): Sill of the variogram |
range |
numeric (>=0): Variogram range |
log.transform |
logical: apply a log transformation to the observations?
(default: FALSE ). |
maxdist |
numeric: maximum distance of nearest points to be used for kriging (search radius) |
nmin |
numeric: Minimum number of points (within the local search neighborhood) required for interpolation. |
nmax |
numeric: Maximum number of nearest points to be used for interpolation |
blocksize |
numeric: block size for block kriging;
block kriging is applied if this parameter is specified.
If blocksize is missing (default), ordinary (point)
kriging is used. |
target |
list: parameters identifying the target area,
e.g. the lower left corner and size of grid, or name of a
reference grid; see rsaga.target . |
... |
Optional arguments to be passed to rsaga.geoprocessor ,
including the env RSAGA geoprocessing environment. |
This function uses module 4 ("Ordinary Kriging") in SAGA
library grid_gridding
(users of the GUI of SAGA GIS should
not be confused by the fact that the "Ordinary Kriging" module appears
first in the GUI's module listing - it is in fact module 4).
The SAGA module support some other variogram models(?), but I am not
quite sure what they are doing, so they (and the associated
additional parameters) are currently
not supported by this wrapper function. The module's usage page
also mentions a FORMULA
argument, but this seems to be a
mistake.
Alexander Brenning (R interface), Olaf Conrad (SAGA module)
rsaga.inverse.distance
,
rsaga.target
; see also
krige
in package gstat
.
## Not run: # Krige attribute 0 from the points shapefile to # a grid with the same extent and resolutionn as the # (pre-existing) geology grid: rsaga.ordinary.kriging("points", "dem", field = 0, maxdist = 1000, target = rsaga.target(target="target.grid", target.grid = "geology")) # Specify a target grid manually (see rsaga.target): rsaga.ordinary.kriging("points", "dem", field = 0, radius = 1000, target = rsaga.target("grid.system", system.nx = 200, system.ny = 300, system.xy = c(604853,7465013), system.d = 50)) ## End(Not run)