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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 the pixel (grid) layer with the 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 takes into account 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 a attribute field value:
    • pass the field name to the Generate method
    • with above the Coordinate property is neglected

The Semivariance property holds a 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 don't cause huge errors

Cons

  • interpolated values don't match the input values (but are very close)

References

2019/01/25 17:03