Figure 6.cg.25 Here, the green points represent known sample points and the red point is an unknown location for which we would like to estimate a value (Z(x)). The distances between sample points and the unknown point are shown in black text, while the attribute values of the sample points are shown in blue. You can see how the distance affects the influence of a point on the estimated value in the equation at the right: nearer points have a significantly greater effect on the estimated value than more distant points.