Kriging from Raster

Command line

The Kriging from Raster operation can be directly executed by typing one of the following expressions on the command line of the Main window:

  

OUTMAP

=

MapKrigingFromRaster(InputRasterMap, SemiVarModel)

OUTMAP

=

MapKrigingFromRaster(InputRasterMap, SemiVarModel, LimDist)

OUTMAP

=

MapKrigingFromRaster(InputRasterMap, SemiVarModel, LimDist, DistanceUnit

OUTMAP

=

MapKrigingFromRaster(InputRasterMap, SemiVarModel, LimDist, Distance Unit, 1|0, min

OUTMAP

=

MapKrigingFromRaster(InputRasterMap, SemiVarModel, LimDist, Distance Unit, 1|0, min, max

where:

OUTMAP

is the name of the output raster map.

MapKrigingFromRaster

is the command to start the Kriging from Raster operation.

InputRasterMap

is the name of the input raster map with a value domain.

SemiVarModel

Model(nugget, sill, range) | Power(nugget, slope, pow)

This expression defines the semi-variogram model that should be used and the expected parameters.

Model

Spherical | Exponential | Gaussian | Wave | RatQuad | Circular

nugget

value for the nugget, according to your semi-variogram (real value).

sill

value for the sill, according to your semi-variogram (real value).

range

value for the range, according to your semi-variogram (real value > 0).

slope

when using the Power model: value for the 'slope'. When pow is specified as 1 (i.e. thus using a linear model), then slope is the direction coefficient, i.e. Dg/Dh.

pow

when using the Power model: an exponent 0 < real value < 2. When you use value 1, the Power model will become linear and the slope will be constant. If the power exponent is 2 the assumed stochastic model (‘randomness’) is not always justifiable and the interpolation can become pathological.

LimDist

A value for the limiting distance: pixels that are farther away from an output pixel than the limiting distance will not be used in the Kriging equations. You can specify a value in meters or in pixels, see DistanceUnit below.
If the DistanceUnit is specified in meters: 0 < limiting distance (real) <= 40 * pixelsize;
if the DistanceUnit is specified in pixels: 0 < limiting distance (integer) <= 40.

DistanceUnit

m | p

Defines whether the limiting distance value is expressed in meters or in pixels.

m

Limiting distance value is expressed in meters.

p

Limiting distance value is expressed in pixels.

1 | 0

Specify whether or not an error map has to be created. The error map will contain the square root of the Kriging error variance values, i.e. standard deviations per pixel. When this parameter is not specified, no error map will be created.

1

Create an error map. The error map will obtain the same name as specified for the output Kriging map followed by the additional string _Error.

0

Do not create an error map.

min, max

Optional parameters to specify the minimum and maximum number of input pixels with a value that should be taken into account per Kriging estimate/prediction, i.e. the number of input pixels with a value within the limiting distance of an output pixel that should be taken into account in the calculation of the output value for that pixel. 1 <= min. nr. of pixels (integer) <= max. nr. of pixels (integer) <= 100.

  • When the minimum is not specified a minimum value 1 will be used. When, for an output pixel, less valid input pixels are found within the specified limiting distance than the specified minimum, no Kriging is performed and the output pixel will become undefined. If the whole map contains less valid input pixels than the specified minimum, an error message will appear and no output will be produced.
  • When the maximum is not specified, value 16 will be used. When, for an output pixel, more valid input pixels are found within the specified limiting distance than the specified maximum, then only the specified maximum number of pixels that are nearest to the output pixel will be used.

When the definition symbol = is used, a dependent output map is created; when the assignment symbol := is used, the dependency link is immediately broken after the output map has been calculated.

Example:

To perform Kriging from Raster on the attribute values in column MyAttribute as present in an attribute table linked to raster map MyRaster,

 

you can use the following expression:

 

OUTMAP

=

MapKrigingFromRaster(MyRaster.MyAttribute,Spherical(10,70,800),20,m,1,5,16)

See also: