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api:dk11:net:tatukgis.ndk.tgis_interpolationkriging

TGIS_InterpolationKriging class

DK11 for .NET | TatukGIS.NDK.TGIS_InterpolationKriging | Classes | Constructors | Methods | Properties

Implementation of the ordinary Kriging interpolation method.

Available also on: Delphi | Java | ActiveX.

Syntax

// C#
public class TGIS_InterpolationKriging : TGIS_VectorToGridAbstract
{
}
' VisualBasic
Public Class TGIS_InterpolationKriging
  Inherits TGIS_VectorToGridAbstract
End Class
// Oxygene
type
  TGIS_InterpolationKriging = public class( TGIS_VectorToGridAbstract )
  end;

Inheritance

→ TGIS_BaseObjectDisposable → TGIS_VectorToGridAbstract

Constructors

Inherited Overrides Protected
Name Visibility Description
TGIS_InterpolationKriging() public

Methods

Inherited Overrides Protected
Name Visibility Description
Generate public Populates a pixel (grid) layer with values resulting from computations based on the set of sample points from the vector layer.
(Overrides TGIS_VectorToGridAbstract.Generate)

Properties

Inherited Protected
Name Visibility Description
Coordinate public Defines which coordinate is taken as interpolation value if the interpolation is not based on an attribute field; default is Z.
(Inherited from TGIS_VectorToGridAbstract)
DefaultValue public If UseDefaultValue is true, then this value will be set for each grid cell for which the interpolated value cannot be computed.
(Inherited from TGIS_VectorToGridAbstract)
MaxPoints public The maximum number of input data points used to interpolate at each grid cell; default is 4.
MinPoints public The minimum number of input data points used to interpolate at each grid cell; default is 4.
Radius public Defines the distance of search for input data points for a grid cell.
Semivariance public Model used for the semivariance calculation; default is power-law.
UseDefaultValue public If true, then each grid cell for which the interpolated value cannot be computed will be set to DefaultValue.
(Inherited from TGIS_VectorToGridAbstract)
Windowed public If True then the windowed version of the algorithm is used; false by default.

Remarks

IDW Splines Kriging Heatmap

Method

The Kriging interpolation method is a geostatistical technique that considers the distance and the degree of variation of the input data.

Usage

There are two different scenarios for generating a Kriging interpolated grid:

  1. based on a Z, M, or Z+M coordinate value:
    • set the Coordinate property to the desired option
    • pass an empty string as the field name to the Generate method
  2. based on an attribute field value:
    • pass the field name to the Generate method
    • with the above, the Coordinate property is neglected

The Semivariance property defines semivariance model implementation. The default semivariance model is Power Law. The complete list of implemented semivariance models:

  • Power Law as TGIS_SemivariancePowerLaw
  • Exponential as TGIS_SemivarianceExponential
  • Gaussian as TGIS_SemivarianceGaussian
  • Spherical as TGIS_SemivarianceSpherical
  • Circular as TGIS_SemivarianceCircular
  • Linear as TGIS_SemivarianceLinear

To implement an additional semivariance model, inherit from TGIS_SemivarianceAbstract, TGIS_SemivarianceWithRange or TGIS_SemivarianceWithSill (depending on the type of semivariance).

Use a windowed version of the algorithm (Windowed=True) for large datasets (thousands of points and more). For up to few hundred points, the non-windowed (full sample) algorithm is efficient enough and gives best possible results. The Radius property is the size of the window in map units. The MinPoints/MaxPoints properties define the minimum/maximum number of sample points necessary/taken to interpolate a grid value.

Pros

  • interpolated values exceed the range of minimum to maximum values of the input data
  • extreme input value changes on short distances do not cause huge errors

Cons

  • interpolated values do not match the input values (but are very close)

References

2020/01/03 01:16