title: Bicubic Interpolation for Non-regular grids?
body: <p>I am working on a project where I have a set of known measurements (x,y,z,a) and an input (z,a). I need to be able to interpolate the (x,y,z) so that I can get a list of possible (x,y) coordinates from a given z.</p>
  
  <p>I was looking at bicubic interpolation, but I can only find examples pertaining to regular grids, and my (x,y) pairs are most certainly not regular.</p>
  
  <p>Basically I am looking for some guidance on algorithms/models to achieve this goal. I am considering a triangulated irregular network, which is attractive because it breaks down into planes which are easy to determine the (x,y) from a given Z. But I would like a little more finesse.</p>
  
  <p>I know it sounds like homework, its not.</p>
  
  <p>Efficiency is not a concern.</p>
  
  <p>Thanks!</p>