Spatial autocorrelation
The principle underlying
spatial interpolation is the First Law of Geography. Formulated by Waldo Tobler, this law states that everything is related to
everything else, but near things are more related than distant things.
The formal property that
measures the degree to which near and distant things are
related is spatial autocorrelation. According to this, if it is raining where
you are, it is probably raining 10 feet away from you, is less likely to be
raining on the other side of town, and might even be clear and sunny 20 miles
away.
Most interpolation methods
apply spatial autocorrelation by giving near sample points more importance than
those farther away.
In this graphic, the darkest triangles indicate the most
influential sample points.