set points without copying

def points(self, points):
        """ set points without copying """
        if not isinstance(points, np.ndarray):
            raise TypeError('Points must be a numpy array')
        # get the unique coordinates along each axial direction
        x = np.unique(points[:,0])
        y = np.unique(points[:,1])
        z = np.unique(points[:,2])
        # Set the vtk coordinates
        self._from_arrays(x, y, z)
        #self._point_ref = points
        self.Modified()