title: Python: Mesh a voxels assembly to compute the surface area
body: <p>I have a voxels assembly which represents a stone in 3D. It's a binarized numpy 3D array in which 1 is assigned to voxels which make up my stone and 0 elsewhere.
  I want to:</p>
  
  <ol>
  <li>create its meshed surface</li>
  <li>calculate the surface area on it. </li>
  </ol>
  
  <p>But how?</p>