title: Scikit Image Marching Cubes
body: <p>I'm using the Scikit Image implementation of the marching cubes algorithm to generate an isosurface. </p>
  
  <pre><code>verts, faces,normals,values = measure.marching_cubes(stack,0)
  </code></pre>
  
  <p>generates the following error: </p>
  
  <blockquote>
    <p>ValueError: need more than 2 values to unpack</p>
  </blockquote>
  
  <p>but </p>
  
  <pre><code> verts, faces = measure.marching_cubes(stack,0)
  </code></pre>
  
  <p>works fine so it seems the algorithm is simply not generating the values for <code>normals</code> and <code>values</code>. Has anyone had any experience with this type of issue?</p>
  
  <p>Furthermore, I don't understand the need for the <code>faces</code> output of the algorithm, as a set of 3 vertices for each triangle in the mesh should be sufficient to describe the isosurface?</p>