Compensating for dimensional variation in 3D printing

1. A method of compensating for dimensional variation in 3D printing comprising:

receiving, by a processor, a voxel space model that represents a 3D object to be printed within a build volume of a 3D printing system;

determining, by the processor, a target subvolume from within the build volume in which the 3D object is to be printed;

determining, by the processor, a voxel erosion scheme based on the determined target subvolume, empirical dimensional data measured from a previously printed object, and a type of build material;

asymmetrically eroding, by the processor, voxels from the voxel space model according to the voxel erosion scheme; and

printing the 3D object based on the eroded voxel space model.

2. A method as in claim 1 , wherein asymmetrically eroding voxels according to the voxel erosion scheme comprises:

determining from the voxel erosion scheme:

a single surface of the voxel space model in at least one of an X dimension, a Y dimension, and a Z dimension of the voxel space model; and

a number of voxels to erode from the single surface.

3. A method as in claim 1 , wherein asymmetrically eroding voxels comprises a first erosion, the method further comprising:

symmetrically eroding, by the processor, voxels from the voxel space model in a second erosion.

4. A method as in claim 1 , wherein determining a voxel erosion scheme comprises determining the voxel erosion scheme from a voxel erosion source selected from an erosion look-up table that associates the target subvolume with the voxel erosion scheme, and user input associated with the 3D object to be printed.

5. A method as in claim 1 , wherein receiving a voxel space model comprises:

receiving, by the processor, a 3D object model that represents the 3D object to be printed; and

converting, by the processor, the 3D object model into the voxel space model.

6. A method as in claim 1 , wherein asymmetrically eroding voxels comprises converting object space voxels at a surface of the voxel space model into non-object space voxels outside the surface of the voxel space model.

7. A dimensional variation compensating 3D printing system comprising:

a memory to receive a voxel space object model that represents a 3D object to be printed within a build volume of the 3D printing system;

a processor programmed to erode voxels at one of two boundary surfaces in at least one of an X, Y, and Z dimension of the voxel space model, both asymmetrically in a first erosion and symmetrically in a second erosion; and

print system components controllable by the processor to print the 3D object according to the eroded voxel space model.

8. A 3D printing system as in claim 7 , wherein:

the voxel space object model comprises positioning information indicating a subvolume within the build volume for printing a portion of the 3D object; and

the processor is programmed to control the erosion of voxels in the voxel space object model associated with the portion of the 3D object according to a voxel erosion scheme associated with the indicated subvolume.

9. A 3D printing system as in claim 8 , further comprising:

an erosion look up table stored in the memory to associate each of a plurality of subvolumes within the build volume with a particular voxel erosion scheme,

wherein the processor is programmed to access a particular voxel erosion scheme from the table based on an indicated subvolume, and to apply the voxel erosion scheme during a voxel erosion operation to control a symmetry, magnitude, and location of voxel erosion to the voxel space model.

10. A 3D printing system as in claim 8 , wherein the build volume comprises numerous subvolumes distinguished based on varying thermal characteristics throughout the build volume.

11. A method of compensating for dimensional variation in 3D printing comprising:

applying asymmetrically, in a first erosion, a morphological operation to a voxel-space object model that represents a 3D object to be printed, the operation selected from a dilation operation to add voxels to the model, and an erosion operation to deplete voxels from the model;

applying symmetrically, in a second erosion, the morphological operation to the voxel-space object model; and

printing the 3D object based on the eroded voxel space model.

12. A method as in claim 11 , wherein applying a morphological operation asymmetrically comprises converting boundary voxels at a boundary surface of the voxel-space object model, the boundary voxels being normal to one of two surfaces in at least one of an X dimension, a Y dimension, and a Z dimension of the voxel space model.