Method for instructing a 3D printing system comprising a 3D printer and 3D printing system

1. A method for instructing a 3D printing system comprising a 3D printer having a printing coordinate system operable to print at least one first object onto an existing object, the method comprising:

obtaining, by at least one camera, at least one image representing at least a part of an existing object;

determining a camera pose of the at least one camera relative to the existing object when the at least one image is captured;

determining an alignment between at least part of the existing object and at least part of a first object to be printed on the existing object based, at least in part, on the determined camera pose;

determining a pose of the existing object relative to a printing coordinate system according to the at least one image; and

directing a 3D printer to print at least part of the at least one first object onto the existing object according to the pose and the alignment.

2. The method according to claim 1 , wherein the at least one image further represents a first part of the 3D printer having a known spatial relationship relative to the printing coordinate system.

3. The method according to claim 2 , further comprising:

computing a translation and a rotation between the first part of the 3D printer and the existing object in a coordinate system of the at least one image.

4. The method according to claim 1 , further comprising:

obtaining at least two images of the existing object captured by the at least one camera, and reconstructing a 3D shape of at least part of the existing object from the at least two images,

wherein the alignment is determined based at least in part on the reconstructed 3D shape.

5. The method according to claim 1 , wherein determining the camera pose comprises determining the camera pose according to a virtual model of the existing object or according to a visual marker rigidly fixed relative to the existing object.

6. The method according to claim 1 ,

wherein the at least one camera is placed at a fixed position relative to the printing coordinate system.

7. The method according to claim 6 , wherein the at least one camera is mounted to the 3D printer.

8. The method according to claim 6 , further comprising computing a pose of the at least one camera in the printing coordinate system in a calibration procedure.

9. The method according to claim 1 , further comprising:

determining the camera pose of the at least one camera when capturing the at least one image relative to the printing coordinate system using a tracking system by computing a pose of the at least one camera and a pose of the printing coordinate system in a tracking coordinate system of the tracking system.

10. The method according to claim 1 , wherein the existing object is within a printing space of the 3D printer.

11. The method according to claim 1 , wherein determining an alignment between at least part of the first object and at least part of the existing object comprises determining the alignment according to a virtual model of the existing object and a virtual model of the first object.

12. The method according to claim 11 , wherein the virtual model of the existing object is computed according to the at least one image.

13. A 3D printing system adapted for printing at least one first object onto an existing object comprising:

a 3D printer provided with a printing coordinate system;

a processing device; and

a memory comprising instructions which, when executed by the processing device, cause the processing device to:

obtain, by at least one camera, at least one image representing at least a part of an existing object;

determine a camera pose of the at least one camera relative to the existing object when the at least one image is captured;

determine an alignment between at least part of the existing object and at least part of a first object to be printed on the existing object based, at least in part, on the determined camera pose;

determine a pose of the existing object relative to a printing coordinate system according to the at least one image; and

direct the 3D printer to print at least part of the at least one first object onto the existing object according to the pose and the alignment.

14. A computer program product comprising a non-transitory computer readable storage medium having computer readable software code sections embodied in the medium, which software code sections are configured to:

obtain, by at least one camera, at least one image representing at least a part of an existing object;

determine a camera pose of the at least one camera relative to the existing object when the at least one image is captured;

determine an alignment between at least part of the existing object and at least part of a first object to be printed on the existing object based, at least in part, on the determined camera pose;

determine a pose of the existing object relative to a printing coordinate system according to the at least one image; and

direct a 3D printer to print at least part of the at least one first object onto the existing object according to the pose and the alignment.

15. The 3D printing system according to claim 13 , wherein the at least one image further represents a first part of the 3D printer having a known spatial relationship relative to the printing coordinate system.

16. The 3D printing system according to claim 15 , further comprising instructions to:

compute a translation and a rotation between the first part of the 3D printer and the existing object in a coordinate system of the at least one image.

17. The 3D printing system according to claim 13 , further comprising instructions to:

obtain at least two images of the existing object captured by the at least one camera, and reconstructing a 3D shape of at least part of the existing object from the at least two images,

wherein the alignment is determined based at least in part on the reconstructed 3D shape.

18. The computer program product according to claim 14 , wherein the at least one camera is placed at a fixed position relative to the printing coordinate system.

19. The computer program product according to claim 18 , wherein the at least one camera is mounted to the 3D printer.

20. The computer program product according to claim 18 , further comprising computing a pose of the at least one camera in the printing coordinate system in a calibration procedure.