[R-sig-Geo] generate & plot elevation contour lines

[Edzer J. Pebesma]

karl.sommer at dpi.vic.gov.au wrote:
> Hello list
>
> I am making reference to the graph gallery at
> http://r-spatial.sourceforge.net/gallery
> I was wondering how one would go about adding elevation contour lines to
> the
> example fig08?  Presuming that one would have access to a number of
> geo-referenced
> elevation measurements with a similar density as the sampling locations
> indicated with a grey x in fig08. Is there a method to generate contour
> lines from such information and overlay it onto the existing interpolated
> graph?
>
> Cheers
>
> Karl Sommer
> ________________________________
Simpler than I thought it would be: add contour = TRUE to the argument list
of spplot.

If you want the actual contours, there is a contourLines function that 
returns them; sp has a function to convert these to 
SpatialLinesDataFrame objects: contourLines2SLDF().
--
Edzer