Curve chain connections under surface, distance, and shape constraints

1. A method performed by a product data management (PDM) data processing system, comprising:

receiving a graphic model having a plurality of curves forming a curve chain;

defining a distance threshold and angle threshold corresponding to the graphical model;

optimizing the curve chain under shape constraints, including

selecting two of the plurality of curves of the curve chain,

adjusting a control point at a curve end of each of the selected curves to a point in the middle of the curve ends, and

adjusting a second control point of each of the selected curves by projecting each second control point to a gap angle bisector between the selected curves;

identifying a surface associated with the curve chain;

optimizing the curve chain with under surface and distance constraints with respect to the identified surface; and

storing the graphical model with the optimized curve chain.

2. The method of claim 1 , wherein each of the curves is a b-spline curve.

3. The method of claim 1 , wherein optimizing the curve chain under shape constraints ensures G 0 and G 1 continuity between the plurality of curves in the curve chain.

4. The method of claim 1 , wherein each of the optimizing processes is performed for each of the curves in the curve chain.

5. The method of claim 1 , wherein after optimizing the curve chain with under surface and distance constraints, the system optimizes the curve chain under shape constraints again.

6. A method performed by a product data management (PDM) data processing system, comprising:

receiving a graphic model having a plurality of curves forming a curve chain;

defining a distance threshold and angle threshold corresponding to the graphical model;

optimizing the curve chain under shape constraints;

identifying a surface associated with the curve chain;

optimizing the curve chain with under surface and distance constraints with respect to the identified surface, including

defining a normal plane corresponding to a surface normal at a curve end of two selected curves of the curve chain,

projecting control points of each of the selected curves to the normal plane,

applying an on-surface distance constraint with respect to a defined location, and

adjusting a second control point of each of the selected curves within the normal plane so that the selected curves are as close as possible to the defined location; and

storing the graphical model with the optimized curve chain.

7. A product data management (PDM) data processing system, comprising:

at least one processor; and

an accessible memory, wherein the PDM data processing system is configured to:

receive a graphic model having a plurality of curves forming a curve chain;

define a distance threshold and angle threshold corresponding to the graphical model;

optimize the curve chain under shape constraints, including

selecting two of the plurality of curves of the curve chain,

adjusting a control point at a curve end of each of the selected curves to a point in the middle of the curve ends, and

adjusting a second control point of each of the selected curves by projecting each second control point to a gap angle bisector between the selected curves;

identify a surface associated with the curve chain;

optimize the curve chain with under surface and distance constraints with respect to the identified surface; and

store the graphical model with the optimized curve chain.

8. The PDM data processing system of claim 7 , wherein each of the curves is a b-spline curve.

9. The PDM data processing system of claim 7 , wherein optimizing the curve chain under shape constraints ensures G 0 and G 1 continuity between the plurality of curves in the curve chain.

10. The PDM data processing system of claim 7 , wherein each of the optimizing processes is performed for each of the curves in the curve chain.

11. The PDM data processing system of claim 7 , wherein after optimizing the curve chain with under surface and distance constraints, the system optimizes the curve chain under shape constraints again.

12. A product data management (PDM) data processing system, comprising:

at least one processor; and

an accessible memory, wherein the PDM data processing system is configured to:

receive a graphic model having a plurality of curves forming a curve chain;

define a distance threshold and angle threshold corresponding to the graphical model;

optimize the curve chain under shape constraints;

identify a surface associated with the curve chain;

optimize the curve chain with under surface and distance constraints with respect to the identified surface, including

defining a normal plane corresponding to a surface normal at a curve end of two selected curves of the curve chain,

projecting control points of each of the selected curves to the normal plane,

applying an on-surface distance constraint with respect to a defined location, and

adjusting a second control point of each of the selected curves within the normal plane so that the selected curves are as close as possible to the defined location; and

store the graphical model with the optimized curve chain.

13. A non-transitory computer-readable medium encoded with executable instructions that, when executed, cause a product data management (PDM) data processing system to:

receive a graphic model having a plurality of curves forming a curve chain;

define a distance threshold and angle threshold corresponding to the graphical model;

optimize the curve chain under shape constraints, including

selecting two of the plurality of curves of the curve chain,

adjusting a control point at a curve end of each of the selected curves to a point in the middle of the curve ends, and

adjusting a second control point of each of the selected curves by projecting each second control point to a gap angle bisector between the selected curves;

identify a surface associated with the curve chain;

optimize the curve chain with under surface and distance constraints with respect to the identified surface; and

store the graphical model with the optimized curve chain.

14. The computer-readable medium of claim 13 , wherein each of the curves is a b-spline curve.

15. The computer-readable medium of claim 13 , wherein optimizing the curve chain under shape constraints ensures G 0 and G 1 continuity between the plurality of curves in the curve chain.

16. The computer-readable medium of claim 13 , wherein each of the optimizing processes is performed for each of the curves in the curve chain.

17. The computer-readable medium of claim 13 , wherein after optimizing the curve chain with under surface and distance constraints, the system optimizes the curve chain under shape constraints again.

18. A non-transitory computer-readable medium encoded with executable instructions that, when executed, cause a product data management (PDM) data processing system to:

receive a graphic model having a plurality of curves foaming a curve chain;

define a distance threshold and angle threshold corresponding to the graphical model;

optimize the curve chain under shape constraints;

identify a surface associated with the curve chain;

optimize the curve chain with under surface and distance constraints with respect to the identified surface, including

defining a normal plane corresponding to a surface normal at a curve end of two selected curves of the curve chain,

projecting control points of each of the selected curves to the normal plane,

applying an on-surface distance constraint with respect to a defined location, and

adjusting a second control point of each of the selected curves within the normal plane so that the selected curves are as close as possible to the defined location; and

store the graphical model with the optimized curve chain.