Spherekit: Overview |
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Spherekit is an integrated toolkit for spatial interpolation and comparison of spatial interpolation algorithms. It is UNIX-based and includes a complete graphical user interface (GUI). It uses Generic Mapping Tools (GMT) for display of interpolated fields. The package features several unique capabilities:

**Large-scale interpolation**

Spherekit permits interpolation over
continental or global scales because its computations are based upon
spherical
distances and orientations. Conventional interpolations are based upon
planar projections of the earth, which produce distortions of some
kind over large distances. In Spherekit, projections are applied
only for display purposes,
after the interpolation has been carried out in spherical geometry.
The user can select from a wide range of interpolation algorithms and
can experiment with any associated parameter settings.

** Smart interpolation**

Spherekit permits the user to incorporate knowledge
or information about the processes that produced the spatial variations.
This strategy, also known as "smart interpolation,"
is implemented through the interpolation of user-defined, derived variables.
A simple equation editor is available to
produce combinations of observation variables, and several
nonlinear transforms are built-in.
A digital elevation model (DEM) is included so that elevation can be
treated consistently with other variables.

**Error analysis**

Error analysis is an integrated component of Spherekit.
The performance of an interpolation method and its associated set of
parameters is evaluated using cross-validation. The error at each
observation point is defined as the difference between its actual value
and its estimated value using the remaining n-1 points.
The resulting error field can be displayed either at the data points or
interpolated to a regular grid, to reduce any spatial biases.
Error difference fields, comparing a pair of methods, can be easily
displayed.