Christian Sigg, Ronald Peikert, and Markus Gross.
  <b>Signed Distance Transform Using Graphics Hardware</b>.
  In <i>IEEE Vis2003</i>, 2003.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/g/Sigg-2003-SDT.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Sigg-2003-SDT.bib">(bibtex:
  Sigg-2003-SDT)</A>.<br />