THREE-DIMENSIONAL PRINTING PREPARATION

• US 20130297059A1
• Filed: 04/09/2013
• Published: 11/07/2013
• Est. Priority Date: 04/09/2012
• Status: Active Grant

• Current Assignee: Autodesk, Inc.
• Original Assignee: Autodesk, Inc.
• Inventors: GRIFITH, Saul, WICKE, Martin, PASKO, Keith, IRVING, Geoffrey, CALISCH, Sam, GILMAN, Tucker, BENOIT, Daniel, BACHRACH, Jonathan
• Granted Patent: US 10,248,740 B2
• Time in Patent Office: Days
• US Class Current: 700/98
• CPC Class Codes: B29C 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B33Y 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]
• CPC Class Codes: G06T 17/20 Finite element generation, e.g. wire-frame surface description, tesselation
• CPC Class Codes: G06T 19/20 Editing of 3D images, e.g. changing shapes or colours, aligning objects or positioning parts
• CPC Class Codes: G06T 2219/2021 Shape modification

Abstract

Embodiments disclosed herein provide systems and methods for preparing geometry for 3D printing. In one embodiment, a 3D printing preparation application receives 3D geometry and repairs non-manifold edges and non-manifold vertices, producing a topological manifold geometry. The 3D printing preparation application then welds coincident edges without coincident faces and fills holes in the geometry. The 3D printing preparation application may further perform resolution-aware thickening of the geometry by estimating distances to a medial axis based on distances to distance field shocks, and advecting the distance field using a velocity field. A similar approach may be used to perform resolution-aware separation enforcement. Alternatively, one component may be globally thickened and subtracted from another for separation enforcement. The 3D printing preparation application may also split large models and add connectors for connecting the split pieces after printing. In addition, the 3D printing preparation application may generate a 3D print preview.

Claims

1. A computer-implemented method for preparing 3D geometry for 3D printing, comprising:

receiving the 3D geometry;

identifying one or more non-manifold edges in the 3D geometry;

for each non-manifold edge, separating the non-manifold edge into a plurality of edges corresponding to faces meeting at the non-manifold edge, to create a set of patches;

orienting the patches so that coincident faces have topologically consistent normals; and

iteratively stitching boundaries of the patches together.

2. The method of claim 1, wherein the boundaries are stitched together by stitching a longest zip first, wherein each zip is a boundary between a set of patches which does not change within the zip, and wherein, for any zip, patches with normals incident to the zip have the largest dot product are stitched first.

3. The method of claim 1, further comprising:

identifying one or more non-manifold vertices; and

duplicating the non-manifold vertices and assigning the duplicated vertices to respective surface components.

4. The method of claim 1, further comprising:

determining boundaries of holes in the 3D geometry; and

for each hole, recursively inserting edges in the hole to fill the hole.

5. The method of claim 4, wherein the edges are inserted based on priority criteria, the priority criteria being one of shortest edges first, edges along a preferred direction first, and edges closest to a predefined surface first.

6. The method of claim 4, further comprising:

checking for intersections with the received 3D geometry while inserting edges; and

if an intersection is identified, recursively splitting the new triangle and moving the split point to avoid the intersection.

7. The method of claim 1, further comprising:

identifying edges close in absolute distance but far in geodesic distance; and

inserting triangles into the 3D geometry to connect the identified edges.

8. The method of claim 7, further comprising, repairing the inserted triangles by at least one of performing edge flips, decimations, and edge collapses.

9. The method of claim 7, further comprising, splitting coincident edges.

10. A computer-readable storage medium storing instructions, which when executed by a computer system, perform operations for preparing 3D geometry for 3D printing, the operations comprising:

receiving the 3D geometry;

identifying one or more non-manifold edges in the 3D geometry;

for each non-manifold edge, separating the non-manifold edge into a plurality of edges corresponding to faces meeting at the non-manifold edge, to create a set of patches;

orienting the patches so that coincident faces have topologically consistent normals; and

iteratively stitching boundaries of the patches together.

11. The computer-readable storage medium of claim 10, wherein the boundaries are stitched together by stitching a longest zip first, wherein each zip is a boundary between a set of patches which does not change within the zip, and wherein, for any zip, patches with normals incident to the zip have the largest dot product are stitched first.

12. The computer-readable storage medium of claim 10, the operations further comprising:

identifying one or more non-manifold vertices; and

duplicating the non-manifold vertices and assigning the duplicated vertices to respective surface components.

13. The computer-readable storage medium of claim 10, the operations further comprising:

determining boundaries of holes in the 3D geometry; and

for each hole, recursively inserting edges in the hole to fill the hole.

14. The computer-readable storage medium of claim 13, wherein the edges are inserted based on priority criteria, the priority criteria being one of shortest edges first, edges along a preferred direction first, and edges closest to a predefined surface first.

15. The computer-readable storage medium of claim 13, the operations further comprising:

checking for intersections with the received 3D geometry while inserting edges; and

if an intersection is identified, recursively splitting the new triangle and moving the split point to avoid the intersection.

16. The computer-readable storage medium of claim 10, the operations further comprising:

identifying edges close in absolute distance but far in geodesic distance; and

inserting triangles into the 3D geometry to connect the identified edges.

17. The computer-readable storage medium of claim 16, the operations further comprising, repairing the inserted triangles by at least one of performing edge flips, decimations, and edge collapses.

18. The computer-readable storage medium of claim 16, further comprising, splitting coincident edges.

19. A system, comprising:

a processor; and

a memory, wherein the memory includes an application program configured to perform operations for preparing 3D geometry for 3D printing, the operations comprising;

receiving the 3D geometry,

identifying one or more non-manifold edges in the 3D geometry,

for each non-manifold edge, separating the non-manifold edge into a plurality of edges corresponding to faces meeting at the non-manifold edge, to create a set of patches,

orienting the patches so that coincident faces have topologically consistent normals, and

iteratively stitching boundaries of the patches together.

20. The system of claim 19, wherein the boundaries are stitched together by stitching a longest zip first, wherein each zip is a boundary between a set of patches which does not change within the zip, and wherein, for any zip, patches with normals incident to the zip have the largest dot product are stitched first.

21. The system of claim 19, the operations further comprising:

identifying one or more non-manifold vertices; and

duplicating the non-manifold vertices and assigning the duplicated vertices to respective surface components.

22. The system of claim 19, the operations further comprising:

determining boundaries of holes in the 3D geometry; and

for each hole, recursively inserting edges in the hole to fill the hole, wherein the edges are inserted based on priority criteria, the priority criteria being one of shortest edges first, edges along a preferred direction first, and edges closest to a predefined surface first.

23. The system of claim 19, the operations further comprising:

identifying edges close in absolute distance but far in geodesic distance; and

inserting triangles into the 3D geometry to connect the identified edges.

24. A computer-implemented method for preparing geometry for 3D printing, comprising:

receiving the 3D geometry;

estimating distances from points on a surface of the 3D geometry to a medial axis of the 3D geometry based on distances to shocks of a distance field; and

advecting the distance field using a velocity field to thicken portions of the 3D geometry.

25. The method of claim 24, wherein the shocks occur where the distance field is not C₁ continuous.

26. The method of claim 24, wherein the velocity field is substantially 1 where the estimated distance to the medial axis is less than a printer resolution R, and 0 otherwise.

27. The method of claim 24, further comprising:

deleting geometry which is affected by the advection;

extract a surface of the advected distance field in cells that have moved significantly; and

stitching the extracted surface together to form a new watertight surface.

28. The method of claim 24, wherein the 3D geometry is to be filled with a plurality of materials, further comprising:

for each part of the geometry to be filled with a unique material, determining a surface that is equidistant from the respective part and the union of all other parts having respective unique materials; and

filling volumes bounded by the outer surface of the geometry, the equidistance surfaces, and the original surface before thickening, with the same material as that of the part of the geometry filled with the unique material that is closest to the respective volumes.