library(sgeostat)
library(akima)
data(maas)

grid <- list(x=seq(min(maas$x), max(maas$x), length=40),
           y=seq(min(maas$y), max(maas$y), length=40))

grid$linip <- interp(maas$x, maas$y, maas$zinc, grid$x,grid$y)
image(grid$x, grid$y, grid$linip$z)
contour(grid$x, grid$y, grid$linip$z,add=T)
points(maas$x, maas$y, pch="x")

grid$spline <- interp.new(maas$x, maas$y, maas$zinc, grid$x, grid$y, linear=F)
image(grid$x, grid$y, grid$spline$z)
contour(grid$x, grid$y, grid$spline$z, add=T)
points(maas$x, maas$y, pch="x")