title: 2D Interpolation of Large Irregular Grid to Regular Grid
body: <p>I have 2048x2048 mesh of irregular data <code>zi = f(xi, yi)</code> which are essentially three independent sets of 2048 real values.  I need to smoothly interpolate (perhaps bicubic spline) that into a regular mesh of <code>wi = f(ui, vi)</code> where <code>ui</code> and <code>vi</code> are integer values from 0 to 2047.  </p>
  
  <p>I have tried griddata which seems to work well at images less than 1000x1000, but blows up as you get to 1500x1500 (memory qhull errors for the Delaunay Mesh evidently). I have looked at some of <code>ndimage</code> functions, namely <code>geometric_transform</code>, <code>RectBivariateSpline</code> and <code>map_coordinates</code>, but they all seem to take regularized data as input. I could be missing something and just implementing it wrong though too!</p>
  
  <p>I am trying to use Python/SciPy to do what this Matlab script I have been doing using <code>tformarray</code> and <code>makeresampler</code>.  Any suggestions as to what function I can use to process this large data set?  Thanks!</p>