Spatial interpolation - Spatial Data Analysis: An Introduction for GIS Users - page 133

0 25 50 m

Concentration (ppm)
High : 1505.32
Low : 0.14

0 25 50 m

A B N

0 25 50 m

C

Figure 9.4 (A) Walker Lake sample data locations, (B) map derived using IDW
with eight nearest neighbours, and (C) TIN.

9.4.1 Trend surface analysis

As summarized in Section 9.2, a trend surface is i tted using regression, but instead
of regressing dif erent variables, values are predicted using a regression of the depen-
dent variable (e.g. elevation) against the coordinates or some function of them.