Virtual object volumes

1. A method comprising:

receiving, at a processor, an indication of a volume of a fabrication chamber;

determining, by a processor, a characteristic of a build material for use in fabricating one or more objects within the fabrication chamber;

based on the build material characteristic, scaling, by a processor, a fabrication chamber volume to obtain a virtual object volume, wherein the virtual object volume provides a virtual boundary within which to position unscaled virtual objects representing the objects to be generated in the fabrication chamber, prior to shrinkage of the unscaled virtual objects;

positioning, by the processor, at least one of the virtual objects within the virtual object volume for corresponding physical generation of at least one corresponding of the objects;

determining, by the processor, object generation instructions based on the at least one of the virtual objects as positioned within the virtual object volume; and

causing, by the processor, the at least one corresponding of the objects to be physically generated in accordance with the object generation instructions.

2. The method according to claim 1 , wherein the virtual object volume is determined by applying a shrinkage factor to the fabrication chamber volume, the shrinkage factor being based on the determined build material characteristic.

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

scaling at least one of the the virtual object by a shrinkage compensation factor,

wherein the object fabrication instructions are further determined based on the at least one of the virtual objects as scaled.

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

determining, by the processor, at least one counter-indicated fabrication zone,

wherein the virtual object volume is determined to exclude the counter-indicated fabrication zone.

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

determining, by the processor, an intended object quality,

wherein the virtual object volume is determined by determining a virtual boundary volume intended to be outside the virtual object volume,

and wherein a size of the virtual boundary volume is determined based on the build material and the intended object quality.

6. A non-transitory machine readable medium storing instructions that when executed by a processor cause the processor to:

determine a first accessible object volume within a fabrication chamber of an additive manufacturing apparatus, wherein the first accessible object volume is one of a plurality of accessible object volumes, each of the plurality of accessible object volumes being associated with one of a plurality of build materials and having different dimensions;

generate a virtual representation of the first accessible object volume;

position a model of an object to be generated within the first accessible object volume;

display the model of the object within the virtual representation of the accessible object volume, wherein the model of the object is first positioned and then displayed with intended dimensions of the object after shrinkage;

determine object generation instructions based on the model of the object as positioned within the first accessible object volume; and

cause the object to be physically generated in accordance with the object generation instructions.

7. The non-transitory machine readable medium according to claim 6 , wherein the instructions when executed by the processor cause the processor to further:

scale the object model to compensate for shrinkage in object generation,

wherein the scaling may cause at least a portion of the scaled object model to extend beyond the first accessible object volume.

8. An additive manufacturing apparatus comprising:

a processor; and

a memory storing instructions executable by the processor to:

report a plurality of accessible object volumes of the additive manufacturing apparatus, each of the plurality of accessible object volumes being associated with a build material and having different dimensions, wherein each of the accessible object volumes is smaller than an additive manufacturing apparatus fabrication chamber volume;

receive an indication of a virtual build volume comprising a virtual object arranged within an accessible object volume selected from the plurality of accessible object volumes based on a selected build material of an object to be generated, wherein the virtual object has intended dimensions of the object after shrinkage; and

cause the object to be generated in the additive manufacturing apparatus fabrication chamber volume in correspondence with arrangement of the virtual object within the accessible object volume.

9. The additive manufacturing apparatus according to claim 8 , wherein the instructions are executable by the processor to further:

scale a content of the virtual build volume to compensate for the shrinkage during object generation.

10. The additive manufacturing apparatus according to claim 8 , wherein the instructions are executable by the processor to further:

report the plurality of accessible object volumes of the additive manufacturing apparatus which are associated with different build materials.

11. Additive The additive manufacturing apparatus according to claim 8 , wherein the instructions are executable by the processor to further: reporting module is to

report the plurality of accessible object volumes of the additive manufacturing apparatus that are associated with the build material of one of the plurality of accessible object volumes and either or both of a counter-indicated fabrication chamber zone and an object generation quality indication.

12. The method according to claim 1 , wherein the virtual object volume is smaller than the volume of the fabrication chamber and limits a volume within the fabrication chamber in which objects are to be generated.

13. The method according to claim 1 , wherein the build material characteristic comprises a characteristic of the build material when used with a particular print agent.

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

determining, by the processor, a first virtual object volume in response to selection of a first build material having a first build material characteristic; and

determining, by the processor, a second virtual object volume, that is smaller than the first virtual object volume, in response to selection of a second, different build material having a second build material characteristic.

15. The method according to claim 2 , wherein the shrinkage factor comprises a different shrinkage factor for different orthogonal directions of the fabrication chamber volume.

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

after applying the shrinkage factor to the fabrication volume, applying, by the processor, the shrinkage factor to the at least one of the virtual objects representing the at least one corresponding of the objects to be generated in the fabrication chamber.

17. The additive manufacturing apparatus of claim 8 , further comprising:

an object generation apparatus to physically generate the object in accordance with the object generation instructions.