 particular, no more than two consecutive
 points will be collinear.
<P>
<DD><DL>

<DT><B>Returns:</B><DD>if the convex hull contains 3 or more points, a <A HREF="../../../../com/vividsolutions/jts/geom/Polygon.html" title="class in com.vividsolutions.jts.geom"><CODE>Polygon</CODE></A>;
 2 points, a <A HREF="../../../../com/vividsolutions/jts/geom/LineString.html" title="class in com.vividsolutions.jts.geom"><CODE>LineString</CODE></A>;
 1 point, a <A HREF="../../../../com/vividsolutions/jts/geom/Point.