Fig. 6
From: An extended triangulation to the Marching Cubes 33 algorithm
a The correct triangulation for the case 10.2 (the interpolant inside the cube is homeomorphic to a cylinder). b The triangulation method proposed by Raman and Wanger. (Left) A triangulation of the convex hull of positive and edge intersection points is built. (Right) Then, the triangles coplanar to the faces of the cube are removed