title: 3D morphable model fitting to an image ( face reconstruction)
body: <p>Currently I was working on fitting the morphable model to a given image (2d image to 3d model) but stucked on fitting algorithm.<br>
  I have read several papers, most rely on optimization technique which is hard to implement for me,such as SNO (blanz99,blanz03), MFF and so on.<br>
  Does anyone have implemented one of the such methods? Can you share the code or something?  </p>
  
  <p>two more question:</p>
  
  <ol>
  <li>how to calculate the derivative of the parameters,especially rendering parameters?</li>
  <li>which fitting algorithm is good and easy to implement?</li>
  </ol>