APPLYING SURFACE OFFSET TO A THREE-DIMENSIONAL OBJECT

Abstract

A method is described in which model data describing a three-dimensional object is received. A first offset is applied to a surface of the object, the first offset being applied to the model data. The model data is converted to voxel data, and a second offset is applied to the surface of the object, the second offset being applied to the voxel data.

Description

Claims

1. A method comprising: receiving model data describing a three-dimensional object;applying a first offset to a surface of the object, the first offset being applied to the model data;converting the model data to voxel data; andapplying a second offset to the surface of the object, the second offset being applied to the voxel data.

2. A method as claimed in claim 1, wherein the second offset is greater than the first offset.

3. A method as claimed in claim 1, wherein applying the second offset comprises adding or removing voxels from the surface of the object.

4. A method as claimed in claim 1, wherein the method comprises generating a layer image comprising a slice of the voxel data of the object, and applying the second offset comprises adding or removing pixels from the layer image, each pixel corresponding to a voxel of a predetermined size.

5. A method as claimed in claim 1, wherein the first offset depends on a property of the object.

6. A method as claimed in claim 5, wherein the property is at least one of a build material of the object, a position of the object within a build volume, the size of the object, the shape of the object, and the proximity of the object to other objects within a build volume.

7. A method as claimed in claim 1, wherein the method comprises identifying a feature of the object having a size less than a threshold, and not applying the second offset to surfaces of the identified feature.

8. A method as claimed in claim 1, wherein the method comprises: receiving further model data describing a further three-dimensional object;applying a further first offset to a surface of the further object, the further first offset being different to the first offset and being applied to the further model data;converting the further model data into further voxel data; andapplying the second offset to the surface of the further object, the second offset being applied to the further voxel data.

9. A method as claimed in claim 8, wherein the method comprises generating a layer image comprising a slice of the voxel data and a further slice of the further voxel data, and applying the second offset comprises adding or removing pixels from the layer image, each pixel corresponding to a voxel of a predetermined size.

10. A 3D printing system comprising: an interface to receive model data describing an object to be printed;a processor;a storage medium storing instructions for execution by the processor, the instructions, when executed by the processor, causing the processor to: apply a first surface offset to the model data, convert the model data to voxel data, and apply a second surface offset to the voxel data; anda printhead to selectively deposit droplets of a functional agent onto a layer of build material based on the voxel data.

11. A 3D printing system as claimed in claim 10, wherein the instructions, when executed by the processor, cause the processor to generate a plurality of bed layer images, each bed layer comprising a slice of the voxel data of the object, and the printhead to selectively deposit droplets of the functional agent onto each of a plurality of layers of build material based on a respective bed layer image.

12. A 3D printing system as claimed in claim 11, wherein the instructions, when executed by the processor, cause the processor to apply the second offset to the voxel data by adding or removing pixels from the bed layer images, each pixel corresponding to a voxel of a predetermined size.

13. A 3D printing system as claimed in claim 11, wherein: the interface is to receive a plurality of model data, each model data describing an object to be printed; and the instructions, when executed by the processor, cause the processor to apply a first surface offset to each of the model data, convert each of the model data to voxel data, and apply a second surface offset to each of the voxel data, wherein the first offset is unique to each of the plurality of model data and the second surface offset is common to the plurality of voxel data.

14. A 3D printing system as claimed in 11, wherein the storage medium stores a profile describing surface offset as a function of position within a build volume, and the instructions, when executed by the processor, cause the processor to generate the first surface offset using the profile and a print position of the object.

15. A non-transitory storage medium storing instructions that, when executed by a processor of a computing device, cause the computing device to: receive model data describing a three-dimensional object;apply a first surface offset to the model data;convert the model data to voxel data; andapply a second surface offset to the voxel data.