Method and apparatus for continuity based smoothing

1. A method comprising:

obtaining a complex modelled surface comprising a control mesh of control vertices, which define multiple smooth surface patches of the complex modelled surface;

receiving input specifying at least a portion of the complex modelled surface to be smoothed;

identifying from the input at least three of the multiple smooth surface patches corresponding to the at least a portion of the complex modeled surface to be smoothed, wherein the at least three surface patches are defined by at least eight of the control vertices from the control mesh;

smoothing the at least a portion of the complex modeled surface based on continuity, wherein the smoothing comprises

determining a measure of continuity at an interface between each pair of adjoining surface patches from the at least three surface patches, and

modifying positions of at least a subset of the at least eight control vertices, thereby modifying the at least three surface patches, by targeting an overall improvement in the measures of continuity for the interfaces between the pairs of adjoining surface patches from the at least three surface patches, while also targeting an overall minimum of modification of positions of the at least eight control vertices; and

processing the modified positions of the at least a subset of the at least eight control vertices within the control mesh of the complex modelled surface for output by a physical device.

2. The method of claim 1 , wherein modifying the positions of the at least a subset of the at least eight control vertices comprises:

obtaining total amounts of change to the at least a subset of the at least eight control vertices of the control mesh, wherein the total amounts of change maximize continuity at the interfaces between the adjoining surface patches; and

changing the positions of the at least a subset of the at least eight control vertices using a percentage of the total amounts of change, wherein the percentage is less than one hundred percent.

3. The method of claim 2 , wherein the smoothing comprises targeting at least one additional constraint for the at least a portion of the complex modeled surface.

4. The method of claim 3 , wherein the at least one additional constraint comprises a flattening of one or more extraordinary points among the control vertices.

5. The method of claim 4 , wherein the flattening is the only additional constraint, and the obtaining the total amounts of change comprises using Adaptive Moment Estimation to maximize continuity at the interfaces between the adjoining surface patches and to flatten the one or more extraordinary points, while minimizing modification of positions of the at least eight control vertices.

6. The method of claim 4 , wherein the smoothing comprises iteratively repeating the determining and the modifying while changes to the positions of the at least a subset of the at least eight control vertices are still possible.

7. The method of claim 2 , wherein the percentage is controlled by user input.

8. The method of claim 2 , wherein receiving the input comprises receiving user input through a brush tool of a user interface of a computer aided design program, and the identifying comprises identifying the at least eight of the control vertices from the control mesh as those control vertices defining surface patches including a first set of surface patches touching any control vertex within a region of the brush tool and a second set of surface patches adjoining the first set of surface patches.

9. The method of claim 1 , wherein the physical device comprises a display device, and processing the modified positions for output comprises rendering at least a portion of the complex modelled surface to the display device.

10. The method of claim 1 , wherein the physical device comprises a permanent storage device, and processing the modified positions for output comprises rendering at least a portion of the complex modelled surface to an output document stored in the permanent storage device.

11. The method of claim 1 , wherein the physical device comprises a digital projector, and processing the modified positions for output comprises rendering at least a portion of the complex modelled surface to an animation document for the digital projector.

12. The method of claim 1 , wherein the physical device comprises one or more computer-controlled manufacturing systems comprising an additive manufacturing machine or a subtractive manufacturing machine, and processing the modified positions for output comprises:

generating toolpath specifications for the additive manufacturing machine or the subtractive manufacturing machine using at least a portion of the complex modelled surface; and

manufacturing at least a portion of a physical structure corresponding to the modified positions with the additive manufacturing machine or the subtractive manufacturing machine using the toolpath specifications generated for the additive manufacturing machine or the subtractive manufacturing machine.

13. A system comprising:

a non-transitory storage medium having instructions of a computer aided design program stored thereon; and

one or more data processing apparatus able to run the instructions of the computer aided design program to perform operations specified by the instructions of the computer aided design program to cause the one or more data processing apparatus to

obtain a complex modelled surface comprising a control mesh of control vertices, which define multiple smooth surface patches of the complex modelled surface;

receive input specifying at least a portion of the complex modelled surface to be smoothed;

identify from the input at least three of the multiple smooth surface patches corresponding to the at least a portion of the complex modeled surface to be smoothed, wherein the at least three surface patches are defined by at least eight of the control vertices from the control mesh;

smooth the at least a portion of the complex modeled surface based on continuity, wherein the instructions cause the one or more data processing apparatus to smooth the at least a portion of the complex modeled surface by causing the one or more data processing apparatus to

determine a measure of continuity at an interface between each pair of adjoining surface patches from the at least three surface patches, and

modify positions of at least a subset of the at least eight control vertices, thereby modifying the at least three surface patches, by targeting an overall improvement in the measures of continuity for the interfaces between the pairs of adjoining surface patches from the at least three surface patches, while also targeting an overall minimum of modification of positions of the at least eight control vertices; and

process the modified positions of the at least a subset of the at least eight control vertices within the control mesh of the complex modelled surface for output by a physical device.

14. The system of claim 13 , comprising one or more computer-controlled manufacturing systems comprising an additive manufacturing machine or a subtractive manufacturing machine, wherein the one or more data processing apparatus are able to run the instructions of the computer aided design program to generate toolpath specifications for the additive manufacturing machine or the subtractive manufacturing machine from at least a portion of the complex modelled surface, and to manufacture at least a portion of a physical structure corresponding to the modified positions with the additive manufacturing machine or the subtractive manufacturing machine using the toolpath specifications generated for the additive manufacturing machine or the subtractive manufacturing machine.

15. A non-transitory computer-readable medium encoding instructions operable to cause data processing apparatus to perform operations comprising:

obtaining a complex modelled surface comprising a control mesh of control vertices, which define multiple smooth surface patches of the complex modelled surface;

receiving input specifying at least a portion of the complex modelled surface to be smoothed;

identifying from the input at least three of the multiple smooth surface patches corresponding to the at least a portion of the complex modeled surface to be smoothed, wherein the at least three surface patches are defined by at least eight of the control vertices from the control mesh;

smoothing the at least a portion of the complex modeled surface based on continuity, wherein the smoothing comprises

determining a measure of continuity at an interface between each pair of adjoining surface patches from the at least three surface patches, and

modifying positions of at least a subset of the at least eight control vertices, thereby modifying the at least three surface patches, by targeting an overall improvement in the measures of continuity for the interfaces between the pairs of adjoining surface patches from the at least three surface patches, while also targeting an overall minimum of modification of positions of the at least eight control vertices; and

processing the modified positions of the at least a subset of the at least eight control vertices within the control mesh of the complex modelled surface for output by a physical device.

16. The non-transitory computer-readable medium of claim 15 , wherein modifying the positions of the at least a subset of the at least eight control vertices comprises:

obtaining total amounts of change to the at least a subset of the at least eight control vertices of the control mesh, wherein the total amounts of change maximize continuity at the interfaces between the adjoining surface patches; and

changing the positions of the at least a subset of the at least eight control vertices using a percentage of the total amounts of change, wherein the percentage is less than one hundred percent.

17. The non-transitory computer-readable medium of claim 16 , wherein the smoothing comprises targeting at least one additional constraint for the at least a portion of the complex modeled surface.

18. The non-transitory computer-readable medium of claim 17 , wherein the at least one additional constraint comprises a flattening of one or more extraordinary points among the control vertices.

19. The non-transitory computer-readable medium of claim 18 , wherein the flattening is the only additional constraint, and the obtaining the total amounts of change comprises using Adaptive Moment Estimation to maximize continuity at the interfaces between the adjoining surface patches and to flatten the one or more extraordinary points, while minimizing modification of positions of the at least eight control vertices.

20. The non-transitory computer-readable medium of claim 18 , wherein the smoothing comprises iteratively repeating the determining and the modifying while changes to the positions of the at least a subset of the at least eight control vertices are still possible.