:returns: opposite vertices of the bounding prism for this 
            object.
        :rtype: ndarray([min], [max])

def get_domain(self):
        """
        :returns: opposite vertices of the bounding prism for this 
            object.
        :rtype: ndarray([min], [max])
        """
        if self.polyhedra != []:
            polyhedras_domain = np.vstack([poly.get_domain() 
                                          for poly in self.polyhedra])
        else:
            polyhedras_domain = np.ones((0, 3))
        points = np.vstack((self.surface.get_domain(), 
                            polyhedras_domain, 
                            self.set_of_points))
        return np.array([points.min(axis=0), points.max(axis=0)])