Abstract: In one example, a representation of a volume of a part to be printed by an additive manufacturing system is generated, where the representation depicts a plurality of voxels. A plurality of slices of the representation are generated. Each slice relates to a plurality of voxels within a first plane. A first process is performed in respect of a slice of the plurality of slices, wherein in the first process at least one voxel that has a predetermined colour and is located on a predetermined surface of the part is identified and a data file is updated to include data representative of the identified at least one voxel. The first process is repeated in respect of another slice. A three-dimensional preview of the part to be printed is generated based on the data file.

Abstract: Examples of the present disclosure relate to a method for packing three dimensional (3D) models. The method comprises identifying a plurality of sections of each 3D model according to curvature profiles of the sections; associating a build material layer thickness to each section of the plurality of sections, whereby each associated build material layer thickness is one of a set of pre-established build material layer thicknesses; packing the plurality of 3D models according to each associated build material layer thickness, whereby packing comprises spatially arranging at least some 3D models in the 3D virtual build volume according to one or more criteria, such that at least some of the sections of different 3D models associated to a same build material layer thickness are arranged in a same region of the 3D virtual build volume.

Abstract: In an example, a method includes receiving, at least one processor, object model data representing at least a portion of a first object that is to be generated by an additive manufacturing apparatus by fusing build material within a fabrication chamber. An indication of an amount of fused build material in a region of the fabrication chamber which is to be below the region in which the first object is to be generated may be determined and a dimensional compensation value to apply to the object model data representing the first object may be determined based on the determined indication. The determined dimensional compensation value may be applied to the object model data to derive modified object model data.

Abstract: Object geometry for three-dimensional printers is described in which a first object to be three-dimensionally printed is identified. Geometry data relating to a geometry of all or part of the first object can be obtained. The geometry data can be compared with a predetermined threshold. A determination can be made as to whether the first object may or may not be adversely affected by a post-processing apparatus that will be used to process the object during a post-processing operation based on the comparison.

Abstract: Object model data modification is described in which object model data defining a first object to be generated by a three-dimensional printer may be obtained. A determination whether the first object is an object that may be adversely affected by a post-processing apparatus during post-processing based on a geometry of the first object to be generated can be made; and if the determination is affirmative, the object model data may be modified by adding a structure to the object model data to create a modified object comprising the first object and the structure, the modified object of a different geometry to the first object so as not to be adversely affected by the post-processing apparatus during the post-processing.

Abstract: In an example, a method includes receiving, by at least one processor, object model data describing a geometry of at least part of at least one object to be generated using additive manufacturing. The object model data defines a first geometrical transformation to be applied to the object model data. It may be determined if a second geometrical transformation is to be applied to the object model data. If a second geometrical transformation is to be applied, the first and second geometrical transformations may be applied to the object model data to determine modified object model data. Otherwise, the first geometrical transformation may be applied to the object geometry to determine modified object model data.

Abstract: A method of printing an envelope for encapsulating at least one 3D printed object, the envelope allowing for removal of the at least one 3D printed object from an additive manufacturing system, the method comprising: monitoring a printing queue for one or more print jobs; determining a size of at least one dimension of the envelope based on the size of the one or more queued print jobs; commencing printing of the one or more queued print jobs and the envelope; and varying the size of the at least one dimension in response to changes in one or more print jobs in the printing queue.

Abstract: In an example, a method includes receiving, at least one processor, voxelised object model data describing at least part of an intended fabrication chamber content to be generated using additive manufacturing. The voxelised object model data may be derived from a first data set modelling a first object as 2D slices and a second data set modelling a second object as a 3D mesh. Data within the voxelised object model data which is derived from the first data set may be identified, and a geometrical transformation may be applied thereto.

Abstract: In an example, a method includes receiving, by at least one processor, object model data describing a first object to be generated in additive manufacturing and an intended object generation location of the first object, wherein the intended object generation location is a relative location within a generic fabrication chamber. The method may further comprise determining, by at least one processor, a location for generation of the first object in a first fabrication chamber, wherein the first fabrication chamber is an intended fabrication chamber of object generation. The location may be an absolute location in the first fabrication chamber which corresponds to the relative location within the generic fabrication chamber.

Abstract: A method of producing a shell layer of an output item in an additive manufacturing process comprises forming a first laterally intermittent shell layer (74) and at least one subsequent laterally intermittent shell layer (76), wherein each laterally intermittent shell layer (74,76) at least partially overlaps and joins with at least one of the other laterally intermittent shell layers.

Abstract: A method is described in which data representing a plurality of three-dimensional objects to be printed in a printing job is received and printer control data is generated based on an attribute to be prioritised for each object. The plurality of three-dimensional objects are printed in one printing job by printing a plurality of successive layers based on the generated printer control data. Printing a layer comprising printing a portion of a first object in a first print mode, wherein a first attribute is prioritised, and printing a portion of a second object in a second print mode, wherein a second attribute is prioritised.

Abstract: In an example, a machine-readable medium stores instructions which, when executed by a processor, cause the processor to: update a 3D printing geometrical compensation model with at least one correction determined using a combination of a dimensional correction determined from measurements of objects generated using a first geometrical compensation and a dimensional correction determined from measurements of objects generated using a modified version of the first geometrical compensation.

Abstract: Examples of the present disclosure relate to a method for packing three dimensional (3D) models. The method comprises identifying a plurality of sections of each 3D model according to curvature profiles of the sections; associating a build material layer thickness to each section of the plurality of sections, whereby each associated build material layer thickness is one of a set of pre-established build material layer thicknesses; packing the plurality of 3D models according to each associated build material layer thickness, whereby packing comprises spatially arranging at least some 3D models in the 3D virtual build volume according to one or more criteria, such that at least some of the sections of different 3D models associated to a same build material layer thickness are arranged in a same region of the 3D virtual build volume.

Abstract: Object model data is obtained, defining an object to be generated by a three-dimensional printer. An envelope is obtained within which the object is to be generated, the envelope having a main section and at least one of a base and/or a lid, and printer control data is generated comprising build data to control a three-dimensional printer to generate the object and the envelope and a build mode data, wherein the printer control data comprises instructions to cause a three-dimensional printer to generate a build layer of the base and/or lid of the envelope using a first build mode, and to generate the object using a second build mode. The first build mode uses an extended time-per-build-layer for the generating of the build layer of the base and/or lid of the envelope compared with the second build mode.

Abstract: Certain examples relate to generating output print data representing at least one object. Output print data is generated by performing a geometric transformation on a part of object model data representing the identified region. The object model data represents the at least one object to be printed. The geometric transformation may use a transformation parameter which is determined based at least on the object model data and object property data. The object obtain input print data comprising property data identifies a region of the at least one object and associates it with a selected physical property.

Abstract: A method of processing merged 3D geometric information in a 3D printing system is described that receives a 3D object model file representing at least two physical 3D parts to be printed, wherein the 3D object model file comprises 3D geometric information for the at least two physical 3D parts, wherein the 3D geometric information is encoded as at least one logical 3D part, wherein at least one of the at least one logical 3D part comprises merged 3D geometric information for at least a subset of the at least two physical 3D parts. From the 3D object model file, a separate set of 3D geometric information for each of the at least two physical 3D parts is extracted and each separate set of 3D geometric information is processed individually before printing the physical 3D parts.

Abstract: In an example, an apparatus comprises processing circuitry, the processing circuitry comprising: memory, to store a two-dimensional pixel representation of a layer of an object to be made in an additive manufacturing process and pixel information, the pixel information specifying pixels representing a surface of the object and colour for the pixels representing the surface; and an image processor, to generate a downscaled representation of the layer and to process the downscaled representation to propagate colour from pixels representing the surface of the object in the downscaled representation to neighbouring pixels representing an interior of the object in the downscaled representation.

Abstract: A method comprising obtaining an input, wherein the input comprises a three-dimensional representation of an object, the three-dimensional representation comprising a plurality of portions, wherein each of the plurality of portions has associated portion properties, and obtaining printer properties of a plurality of printing devices. The printer properties correspond to at least one feature of the printing devices; and the method assigns each of the plurality of portions to respective ones of the plurality of printing devices by comparing the portion properties with the printer properties, and assigning the portion to one of the printing devices based on the comparison, such that each of the plurality of portions has a respective assigned printing device. Each of the portions are then provided to its respective assigned printing device.

Abstract: In an example, a method includes receiving, at least one processor, object model data describing at least part of a three-dimensional object to be generated using additive manufacturing. A model type may be determined from the object model data by at least one processor. When the model type is a mesh model, a volumetric model describing at least part of the three-dimensional object in terms of a plurality of sub-volumes may be determined by at least one processor. When the model type is a volumetric model, the sub-volumes which represent a surface of the three-dimensional object may be determined by at least one processor.

Abstract: An apparatus has a processor and a machine-readable storage medium storing machine-readable instructions executable by the processor. The processor is to create a 3D print job defining a spatial arrangement of objects to be printed such that each object or each object portion is arranged in a region or regions having a build material layer thickness corresponding to a user-specified build material layer thickness and such that objects or object portions having different build material layer thicknesses are arranged in different regions. Different build material layer thicknesses may be user-specified for different objects or different object portions.