Inverse Distance Weighted

Inverse Distance Weighted (IDW) interpolation is simple and easy to use. It only takes an exponent as parameter. The resulting grid always intersects the data points. In 2D a low exponent produces rounded spikes, whereas higher exponents produce steep spikes.

A detailed description of the algorithm is beyond the scope of this documentation
See: http://en.wikipedia.org/wiki/Inverse_distance_weighting for a summary description and references.