Kriging and Cokriging

Kriging uses variograms to compute optimal interpolations with known variance. Cokriging uses variograms for both a primary attribute and a more heavily sampled covariate attribute to interpolate the primary data. GS+ provides Kriging methods that fit various needs:

  • Block and Punctual Kriging
  • Simple, Ordinary, and Indicator Kriging
  • Cokriging

Conditional Simulation

Conditional Simulation uses variograms to provide optimal probability-based interpolations with measured data values honored at their locations. Kriging and other interpolation methods will smooth out local details, which may not be optimal when mapping sharp boundaries such as those for contamination hotspots or fault lines.

  • Map estimated values and variance
  • Map probabilities that values will exceed a threshold
  • Number of simulations is under user control
  • Allows multigrid refinements
  • Use secondary data to improve interpolations

Inverse Distance Weighting (IDW)

Inverse Distance Weighting (IDW) and Normal Distance Weighting (NDW) are classical interpolation techniques based on nearest neighbor weighting. These simple interpolation methods, used in mapping programs that do not use geostatistics, assume spatial dependence among points close to one another without measuring it.

  • Choose Inverse or Normal Weighting
  • Weighting power under user control
  • Adjustable smoothing

Even More Interpolation Features

Interpolation Bounds

Define interpolation boundaries and intensities (grid spacing) for all interpolation methods

Polygon Outlines

Define inclusive and exclusive polygons to map or exclude irregular features

Cross Validation Analysis

Compare actual values against estimated values when a given sample point is temporarily removed from the data set

Jackknife Validation Analysis

Compare estimated values against measured values for locations not included in the data set

Grid Types

Use a regular interpolation grid with constant distance intervals or specify individual locations to interpolate

Define interpolated data boundaries

Constrain interpolated values to a specific range of values

Output data formats

Write output files structured for GS+, ArcView®, ArcInfo®, Surfer®, GSLib, and GeoEas

Define search neighborhoods

Specify the number of neighbors used for interpolating a point and the neighborhood size and shape