Figure 1.

(A) Variogram plot derived from spatial data. A variogram shows the amount of spatial autocorrelation in the data where the parameter ‘Range’ indicates the distance between two observations beyond which observations appear independent. The ‘sill’ is the point at which semi -variance reaches an asymptote. The nugget is the spatial variability at the origin. The variogram plot is created using R-package gstat⁶². (B) The conversion of isotropic spatial coordinates to anisotropic spatial coordinates. The isotropic spatial data has the same amount of spatial autocorrelation in all directions while in anisotropic data particular direction has stronger autocorrelation than other directions. Isotropic data can be converted into anisotropic data using rotation and scaling matrix (see “Material and methods”).