This method performs interpolation within the function fftgrid for fromXYZ objects.
# S3 method for fromXYZ
fftinterpolate(spatial, mcens, ncens, ext, ...)objects of class spatialAtRisk
x-coordinates of interpolation grid in extended space
y-coordinates of interpolation grid in extended space
integer multiple by which grid should be extended, default is 2. Generally this will not need to be altered, but if the spatial correlation decays slowly, increasing 'ext' may be necessary.
additional arguments
matrix of interpolated values