Image processing method and method of three-dimensional printing incorporating the same

1. A method of preparing a virtual three-dimensional object for three-dimensional printing, the method comprising:

obtaining a vector-based surface representation of the virtual three-dimensional object, wherein the vector-based surface representation comprises surfaces of the virtual three-dimensional object enclosing a volume;

sampling the volume enclosed by the vector-based surface representation of the virtual three-dimensional object to generate a digitised three-dimensional representation of the virtual three-dimensional object;

eroding the digitised three-dimensional representation of the virtual three-dimensional object to generate a digitised representation of an internal volume of the virtual three-dimensional object;

generating a vector-based surface representation of the internal volume using the digitized representation of the internal volume of the virtual three-dimensional object, wherein the surfaces of the internal volume represent internal surfaces of the virtual three-dimensional object;

combining the vector-based surface representation of the virtual three-dimensional object with the vector-based surface representation of the internal volume of the virtual three-dimensional object; and

outputting the combined vector-based surface representation using an output device.

2. A method according to claim 1 including inverting the digitised representation of the internal volume before generating the vector-based surface representation of the internal volume, whereby the surfaces of the internal volume automatically represent internal surface upon generating the vector-based surface representation of the internal volume.

3. A method according to claim 2 including performing a union operation to combine a digitised representation of a microstructure with the inverted digitised representation of the internal volume, wherein the combined digitised representation of the internal volume consists of the microstructure.

4. A method according to claim 1 including designating an exterior surface defined by the vector-based surface representation of the internal volume as an internal surface before combining it with the vector-based surface representation of the virtual three-dimensional object.

5. A method according to claim 4 , wherein designating an exterior surface defined by the vector-based surface representation of the internal volume as an internal surface includes reversing the direction of a plurality of surface normals associated with the exterior surface.

6. A method according to claim 4 including, after eroding the digitised three-dimensional representation of the virtual three-dimensional object to generate a digitised representation of the internal volume of the virtual three-dimensional object, subtracting a digitised representation of a microstructure from the digitised representation of the internal volume, wherein the generated digitised representation of the internal volume consists of the microstructure.

7. A method according to claim 1 including applying a microstructure to the digitised representation of the internal volume.

8. A method according to claim 7 , wherein a digitised representation of the microstructure is generated from tri-periodic mathematical functions.

9. A method according to claim 8 including modifying the tri-periodic mathematical functions to introduce density variations inside the internal volume.

10. A method according to claim 7 , wherein a digitised representation of the microstructure is generated by sampling a virtual three-dimensional vector-based model of a microstructure or by scanning a real physical object.

11. A method according to claim 1 , wherein the digitised three-dimensional representation of the virtual three-dimensional object comprises a voxelized model of the virtual three-dimensional object, and wherein eroding the digitised three-dimensional representation of the virtual three-dimensional object comprises removing voxels at the surface of the voxelized model.

12. A method according to claim 11 , wherein eroding the digitised three-dimensional representation of the virtual three-dimensional object comprises removing a layer of voxels from the whole surface of the voxelized model.

13. A method according to claim 12 , wherein the removed layer of voxels has a variable depth.

14. A method according to claim 13 , including determining the variable depth by way of single or multiple computer-based analysis.

15. A method according to claim 1 , wherein combining the vector-based surface representations of the virtual three-dimensional object and the internal volume comprising performing a concatenation operation to unify sets of data corresponding to the vector-based surface representations of the original virtual three-dimensional object and the internal volume respectively.

16. A method according to claim 15 , wherein the sets of data are in STL format.

17. A computer program product comprising a computer-readable storage medium having software instructions stored thereon, the software instructions being executable by a computer to perform the steps of a method according to claim comprising:

obtaining a vector-based surface representation of a virtual three-dimensional object, wherein the vector-based surface representation comprises surfaces of the virtual three-dimensional object enclosing a volume;

sampling the volume enclosed by the vector-based surface representation of the virtual three-dimensional object to generate a digitised three-dimensional representation of the virtual three-dimensional object;

eroding the digitised three-dimensional representation of the virtual three-dimensional object to generate a digitised representation of an internal volume of the virtual three-dimensional object;

generating a vector-based surface representation of the internal volume using the digitized representation of the internal volume of the virtual three-dimensional object, wherein the surfaces of the internal volume represent internal surfaces of the virtual three-dimensional object;

combining the vector-based surface representation of the virtual three-dimensional object with the vector-based surface representation of the internal volume of the virtual three-dimensional object; and

outputting the combined vector-based surface representation using an output device.

18. A method of generating a physical model using three-dimensional printing, the method comprising:

inputting a vector-based surface representation of a virtual three-dimensional object, wherein the vector-based surface representation comprises surfaces of the virtual three-dimensional object enclosing a volume;

sampling the volume enclosed by the vector-based surface representation of the virtual three-dimensional object to generate a digitised three-dimensional representation of the virtual three-dimensional object;

eroding the digitised three-dimensional representation of the virtual three-dimensional object to generate an internal volume of the virtual three-dimensional object;

generating a vector-based surface representation of the internal volume using the digitised representation of the internal volume of the virtual three-dimensional object, wherein the surfaces of the internal volume represent internal surfaces of the virtual three-dimensional object; and

combining the vector-based surface representation of the virtual three-dimensional object with the vector-based surface representation of the internal volume of the virtual three-dimensional object;

outputting the combined vector-based surface representation to a three-dimensional printer; and

operating the three-dimensional printer to create a physical model corresponding to the combined vector-based surface representation.

19. A method of preparing a virtual three-dimensional object for computer-based analysis, the method comprising:

obtaining a vector-based surface representation of the virtual three-dimensional object, wherein the vector-based surface representation comprises surfaces of the virtual three-dimensional object enclosing a volume;

sampling the volume enclosed by the vector-based surface representation of the virtual three-dimensional object to generate a digitised three-dimensional representation of the virtual three-dimensional object;

eroding the digitised three-dimensional representation of the virtual three-dimensional object to generate a digitised representation of an internal volume of the virtual three-dimensional object;

combining the digitised three-dimensional representation of the virtual three-dimensional object with digitised three-dimensional representation of the internal volume; and

performing computer-based analysis on the combined digitised three-dimensional representation.

20. A method according to claim 19 including, after eroding the digitised three-dimensional representation of the virtual three-dimensional object, subtracting a digitised representation of a microstructure from the eroded digitised three-dimensional representation of the virtual three-dimensional object, wherein the generated internal volume consists of the microstructure.

21. A method according to claim 19 including, after eroding the digitised three-dimensional representation of the virtual three-dimensional object, inverting the digitised representation of the internal volume and performing a union operation to combine a digitised representation of a microstructure with the inverted digitised internal volume, wherein the generated internal volume consists of the microstructure.

22. A method according to claim 19 , wherein the computer-based analysis includes finite element and/or finite volume analysis.

23. A method of preparing a virtual three-dimensional object for three-dimensional printing, the method comprising:

scanning a physical three-dimensional object to obtain a digitised three-dimensional representation of the physical three-dimensional object;

eroding the digitised three-dimensional representation of the physical three-dimensional object to generate a digitised representation of an internal volume of the physical three-dimensional object;

subtracting a digitised representation of a microstructure from the digitised representation of the internal volume of the physical three-dimensional object, wherein the generated digitised representation of the internal volume consists of an inverted version of the microstructure; and

subtracting the generated digitised representation of the internal volume from the digitised three-dimensional representation of the physical three-dimensional object to create a hollowed out representation of the physical three-dimensional object.

24. A method according to claim 23 including generating a vector-based surface representation of the hollowed-out representation of the physical three-dimensional object.

25. A method of preparing a virtual three-dimensional object for three-dimensional printing, the method comprising:

scanning a physical three-dimensional object to obtain a digitised three-dimensional representation of the physical three-dimensional object;

eroding the digitised three-dimensional representation of the physical three-dimensional object to generate a digitised representation of an internal volume of the physical three-dimensional object;

inverting the digitised representation of the internal volume of the physical three-dimensional object;

performing a union operation to combine a digitised representation of a microstructure with the inverted digitised representation of the internal volume of the physical three-dimensional object, wherein the generated digitised representation of the internal volume consists of the microstructure; and

combining the digitised three-dimensional representation of the physical three-dimensional object with digitised representation of the internal volume to create a hollowed out representation of the physical three-dimensional object.

26. Apparatus for preparing a virtual three-dimensional object for three-dimensional printing, the apparatus comprising:

an input device for receiving a vector-based surface representation of the virtual three-dimensional object, wherein the vector-based surface representation comprises surfaces of the virtual three-dimensional object enclosing a volume;

a memory arranged to store the vector-based surface representation of the virtual three-dimensional object;

a processor programmed to:

sample the volume enclosed by the vector-based surface representation of the virtual three-dimensional object to generate a digitised three-dimensional representation of the virtual three-dimensional object,

erode the digitised three-dimensional representation of the virtual three-dimensional object to generate a digitised representation of an internal volume of the virtual three-dimensional object,

generate a vector-based surface representation of the internal volume using the digitised representation of the internal volume of the virtual three-dimensional object, wherein the surfaces of the internal volume represent internal surfaces of the virtual three-dimensional object, and

combine the vector-based surface representation of the virtual three-dimensional object with the vector-based surface representation of the internal volume of the virtual three-dimensional object; and

an output device for outputting the combined vector-based surface representation of the virtual three-dimensional object and internal volume.

27. Apparatus according to claim 26 including a display and/or a three-dimensional printer connected to the output device.

28. Apparatus according to claim 26 , wherein the memory has a library comprising a plurality of digitised representations of microstructures stored thereon, and the processor is further programmed to:

permit selection via the input device of a microstructure in the library; and

apply the digitised representation of the selected microstructure to the digitised representation of the internal volume of the virtual three-dimensional object,

wherein the generated digitised representation of the internal volume consists of the microstructure.