R help - Oct 2008 - map + some arbitrary locations' heights: some kind of perspective or contour plot possible?

Hi,

I thought about this but programming it seems rather difficult so I was
wondering if a function exists for this in R (as most of the times it turns out
that it does):
I have a map (shapefile) and for about 50 points on that map (GPS locations) I
have heights. Is there a function which can make a perspective plot or contour
plot or the like from this little data? Or maybe some function I can abuse?

Thanks for any suggestions,
  Werner

Werner Wernersen <pensterfuzzer <at> yahoo.de> writes:
> 
> Hi,
> 
> I thought about this but programming it seems rather difficult so I was 
> wondering if a function exists for
> this in R (as most of the times it turns out that it does):
> I have a map (shapefile) and for about 50 points on that map (GPS
locations)
> I have heights. Is there a
> function which can make a perspective plot or contour plot or the like from
> this little data? Or maybe some
> function I can abuse?
> 
The perspective, image, and contour plots all expect you to have interpolated
to a regular grid first. It is perhaps easiest to use interp() in the akima 
package for this, although there are lots of alternatives. There has just been
a thread on this on R-sig-geo, subject: "interp.old and
write.ascii.grid",
showing how also to export the interpolated values to a grid file.

Roger Bivand
> Thanks for any suggestions,
>   Werner
>