Interpolation: Inverse‐Distance Weighting

The general concept of spatial interpolation is first discussed, particularly in the contexts of spatial sampling and the geographical nature of spatial data. Then two major interpolation approaches, deterministic and statistical/geostatistical, are differentiated. The inverse‐distance weighting (IDW) method is introduced as a specific method using a spatial averaged weighting scheme based upon the inverse of distance between the sampled locations and the location of predicted value. Parameters involved in specifying the IDW method are highlighted using examples to illustrate their impacts on the interpolation results. Limitations, potential algorithmic problems, and an extension of the IDW method are also discussed.