title: griddata runtime error -- Python / SciPy (Interpolation)
body: <p>I use scipy's griddate-function for interpolation.</p>
  
  <p>What does the following error message means which appears when python is executing the griddata-function?</p>
  
  <pre><code>File "C:\Python25\lib\site-packages\scipy\interpolate\ndgriddata.py", line 182, in griddata
  ip = LinearNDInterpolator(points, values, fill_value=fill_value)
  File "interpnd.pyx", line 192, in interpnd.LinearNDInterpolator.__init__ (scipy\interpolate\interpnd.c:2524)
  File "qhull.pyx", line 917, in scipy.spatial.qhull.Delaunay.__init__ (scipy\spatial\qhull.c:4030)
  File "qhull.pyx", line 170, in scipy.spatial.qhull._construct_delaunay (scipy\spatial\qhull.c:1269)
  RuntimeError: Qhull error
  </code></pre>