title: Smoothness of contour lines in contourplot
body: <p>How can I control the smoothness of the contour lines, when plotting a contour plot using the package lattice in R? The default is particularly unpleasing for low resolution images where the contour edges are sharp.</p>
  
  <p>Edit:
  Here is my problem-- the segments join in sharp corners, while I would like a smooth joints.</p>
  
  <pre><code>require(lattice)
  contourplot(volcano[1:10,1:10])
  </code></pre>