Pitney Bowes MapInfo Vertical Mapper - Manual (Page 27)

Chapter 3: Creating Grids Using Interpolation
User Guide
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Choosing an Interpolation Technique
The most challenging task in creating a surface through interpolation is choosing the most
appropriate technique. All interpolation techniques create gridded surfaces; however, the results
may not properly represent how the data behaves through space, such as how the values change
from one location to the next. For example, if an elevation surface is created from sample points
taken in a mountainous area, you need to choose a technique that can simulate the severe elevation
changes because this is how this type of data behaves.
It is not always easy to understand how data behaves before you start the gridding process and,
therefore, it can be difficult to know what technique to use. The answers to the following questions
will help you determine the most appropriate technique to use.
1. What kind of data is it, or, what do the data points represent?
Some interpolation techniques can be automatically applied to certain data types.
Natural Neighbour (Advanced)
The Advanced option gives you access to a variety of controls in the
Natural Neighbour interpolation technique that you can use to make subtle
adjustments to the grid surface generated from a points table.
Rectangular
(Bilinear) Original data points are joined by a network of lines to build a rectilinear
mesh. New grid values are then estimated using the slopes of the double
linear (bilinear) framework formed by the nearest four points.
Kriging Kriging is a geostatistical interpolation technique that considers both the
distance and the degree of variation between known data points when
estimating values in unknown areas. Graphing tools help you understand
and model the directional (for example, north-south, east-west) trends of
your data.
Custom Point
Estimation In Custom Point Estimation, grid cell values are calculated based upon a
user-defined math operation and performed using the data points found
within a given search radius around each cell. Math operations include
sum, minimum, maximum, average, count, and median.