3D modeled object defined by a grid of control points

A non-transitory data storage medium having recorded thereon a computer program comprising instructions for performing a computer-implemented method for designing a 3D modeled object, the method comprising:

• providing, to a computer system, a non-uniform rational B-spline (NURBS) surface that represents the 3D modeled object and that is defined by a grid of control points;
• determining, 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,
• the updating of the surface including updating the grid of control points by optimizing a program that penalizes geometrical deformation of the NURBS surface, under the constraint that the position of the selected subset of surface points be as modified, the program penalizing geometrical deformation of the NURBS surface by penalizing, for each respective control point, a distance between the respective control point before the update and the respective control point after the update.

A CAD system comprising a processor coupled to a memory and a graphical user interface, the memory having recorded thereon a computer program comprising instructions for performing a computer-implemented method for designing a 3D modeled object, the method comprising:

• providing, to a CAD system, a non-uniform rational B-spline (NURBS) surface that represents the 3D modeled object and that is defined by a grid of control points;
• determining, by the CAD 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 CAD 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,
• the updating of the surface including updating the grid of control points by optimizing a program that penalizes geometrical deformation of the NURBS surface, under the constraint that the position of the selected subset of surface points be as modified, the program penalizing geometrical deformation of the NURBS surface by penalizing, for each respective control point, a distance between the respective control point before the update and the respective control point after the update.