Pitney Bowes MapInfo Vertical Mapper - Manual (Page 26)

Types of Interpolation
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Vertical Mapper 3.7
Grid Creation using Interpolation
Interpolation is the process of estimating grid values using measured observations taken from a
point file. New values calculated from the original point observations form a continuous, evenly
spaced grid surface that “fills in the gaps” between the non-continuous points. Many mathematical
formulae can be applied to estimating or interpolating grid values from an existing point file. There is
no perfect solution, and many techniques are in use. The validity of each method depends entirely
upon the type of data being interpolated, and each generates a unique style of interpolation surface.
Types of Interpolation
The Interpolation Wizard enables you to create grid files using six different techniques. The Natural
Neighbour technique has two variants: simple and advanced.
Triangulation
with Smoothing Original data points are joined by a network of lines to build a mesh of
triangular faces, called a Triangular Irregular Network (TIN). These faces
represent the original data surface. New grid values are then estimated
according to the slope of the TIN surface at the nearest points.
Inverse Distance
Weighting Original data points lying within a prescribed radius of a new grid node are
weighted according to their distance from the node and then averaged to
calculate the new grid cell value.
Natural
Neighbour A network of natural neighbour regions (Voronoi diagram) is built using the
original data. This creates an area of influence for each data point that is
used to assign new values to overlying grid cells
Natural Neighbour (Simple)
The Simple option offers the first-time user a two-step process for
implementing the interpolation technique. Many of the controls have been
pre-set to generate the most appropriate surface given the distribution of
points.