def points(self):
        """ returns a pointer to the points as a numpy object """
        # Get grid dimensions
        nx, ny, nz = self.dimensions
        nx -= 1
        ny -= 1
        nz -= 1
        # get the points and convert to spacings
        dx, dy, dz = self.spacing
        # Now make the cell arrays
        ox, oy, oz = self.origin
        x = np.insert(np.cumsum(np.full(nx, dx)), 0, 0.0) + ox
        y = np.insert(np.cumsum(np.full(ny, dy)), 0, 0.0) + oy
        z = np.insert(np.cumsum(np.full(nz, dz)), 0, 0.0) + oz
        xx, yy, zz = np.meshgrid(x,y,z, indexing='ij')
        return np.c_[xx.ravel(), yy.ravel(), zz.ravel()]
returns a pointer to the points as a numpy object