title: how to get geotiff image
body: <p>I want to have a Geotiff image in R.How can I do that? Following is a simple example. I want to have the produced plot in Geotiff format.</p>
  
  <pre><code>require(gstat)
  data(meuse)
  coordinates(meuse) = ~x+y
  data(meuse.grid)
  gridded(meuse.grid) = ~x+y
  m &lt;- vgm(.59, "Sph", 874, .04)
  # ordinary kriging:
  x &lt;- krige(log(zinc)~1, meuse, meuse.grid, model = m)
  spplot(x["var1.pred"], main = "ordinary kriging predictions")
  </code></pre>