Spatial Interpolation Techniques 165
8.2.5 Ordinary Kriging
Ordinary kriging (OK) is similar to SK and the only difference is that OK
estimates the value of the attribute using equations 8.9 and 8.13 by replacing
µ with a local mean µ(x
0
) that is the mean of samples within the search
window, and forcing [1 −
P
n
i=1
λ
i
] = 0 that is
P
n
i=1
λ
i
= 1, which is achieved
by plugging it into equation 8.13. OK estimates the local constant mean, then
performs SK on the corresponding residuals, and only requires the stationary
mean of the local search window.
8.2.6 Kriging with a Trend
Kriging with a trend (KT) is normally called universal kriging (UK) and was
proposed by Matheron in 1969. It is an extension of OK by incorporating
the local trend within the neighbourho