It is provided a computer-implemented method for designing a 3D modeled object, comprising providing, to a computer system, a NURBS surface that represents the 3D modeled object and that is defined by a grid of control points; determining (S20), by the computer system, a grid of surface points that belong to the NURBS surface, the grid of surface points corresponding to the grid of control points according to a predetermined invertible function; displaying, by the computer system, the NURBS surface and, on the NURBS surface, the grid of surface points; selecting, by graphical user-interaction, a subset of the surface points; modifying, by graphical user-interaction, position of the selected subset of surface points, and accordingly, updating real-time, by the computer system, the surface, the update being performed according to the predetermined invertible function.Such a method improves the design of a 3D modeled object.