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, a machine-readable medium stores instructions which, when executed by a processor may cause the processor to modify data for characterising geometrical modifications for use by each of a plurality of additive manufacturing apparatus, wherein a modification for a particular additive manufacturing apparatus is based on dimensions of objects generated by that apparatus.

Abstract: A system includes a controller to receive data corresponding to an object or slices of the object to be generated by a 3D printer, wherein the 3D printer includes an array of printhead nozzles to selectively eject a print agent on a layer of build material in a build chamber having a build chamber wall, the array of printhead nozzles spanning substantially the full width of the build chamber and moveable along a length of the build chamber. The controller to generate first print data used to generate layers of the object based on the received object data, and to generate second print data used to generate layers of a sacrificial barrier located between the object and the build chamber wall, the second print data is generated such that different parts of the sacrificial barrier are generated using a different plurality of nozzles of the array of printhead nozzles.

Abstract: In an example, a method includes generating a training dataset for an inference model to generate dimensional modifications to apply to object models to compensate for departures from model dimensions in objects generated using additive manufacturing based on those object models. Generating the training dataset may include acquiring, for each of a plurality of generated objects, (i) an indication of a first dimensional inaccuracy and a second dimensional inaccuracy, wherein the first and second dimensional inaccuracies are acquired in a direction of a first axis and relate to respective first and second object dimensions; and (ii) an indication of object placement within a fabrication chamber during object generation.

Abstract: In an example, a method includes receiving, at least one processor, object model data representing at least a portion of an object that is to be generated by an additive manufacturing apparatus by fusing build material within a fabrication chamber, wherein the object model data comprises a mesh model comprising data describing a surface of the object. A geometrical compensation vector may be determined for the object model data, the geometrical compensation vector having a first component applying to a first axis of the fabrication chamber and a second component applying to a second axis of the fabrication chamber. A geometrical compensation to apply to at least one location on the surface of the object may be determined by determining a product of the geometrical compensation vector and a vector indicative of the normal of the object surface at the location and the determined geometrical compensation may be applied to the object model data to generate modified object model data.

Abstract: An apparatus has a processor and a machine-readable storage medium storing machine-readable instructions executable by the processor. The machine-readable instructions cause the processor to, upon obtaining an indication that a calibration of a 3D printing machine is to be performed, arrange user calibration objects to be printed and calibration objects to be printed and to be used in the calibration in a virtual build volume. Arranging calibration objects in the virtual build volume comprises arranging the calibration objects at print job specific locations reserved for calibration objects and/or replacing user objects with calibration objects.

Abstract: Example implementations relate to compensating for shrinkage in 3D printing. One example implementation receives an object model to print a corresponding object in a three-dimensional (3D) printer, the object model having a plurality of surface coordinates. A plurality of dimensional modification compensation factors are determined dependent on respective locations within a printing volume of the 3D printer. The object model is adjusted at the plurality of surface coordinates using respective dimensional modification compensation factors depending on the location of the surface coordinates within the printing volume in order to generate a printable object model.

Abstract: In certain examples, a method comprises determining a fusing area density distribution of a build layer from build data relating to a build layer of a three-dimensional model to be printed by an additive manufacturing system. The method comprises, in response to a determination that a region of the build layer has a fusing area density outside of a fusing area density tolerance window, modifying the build layer to define a build layer in which the region has a fusing area density that is within the fusing area density tolerance window.

Abstract: An example method to control a 3D printing system is described. In that example a print agent is selectively deposited onto a portion of a build material layer and based on a reflectance of the portion of the build material layer, an amount of energy to be applied to the portion is determined.

Abstract: An example method includes acquiring a model of an object to be generated in three-dimensional object generation which is segmented into a plurality of object model sub-volumes, each sub-volume representing a region of the object which is individually addressable in object generation. Object model sub-volumes within a first depth of an object model surface are defined at a first resolution and object model sub-volumes beyond the first depth are defined at a second resolution, and the first resolution is a higher resolution than the second resolution. An object generation model is applied to the object model to determine at least one predicted dimensional deviation of the object in object generation. A geometric adjustment to the segmented object model may be determined to compensate for the predicted dimensional deviation by adding and/or removing at least one object model sub-volume defined at the first resolution.

Abstract: In one example, an apparatus comprising a controller to instruct a build platform to support a plurality of layers of build material in a build zone, wherein the build platform is moveable during a build of a three-dimensional object to change the size of the build zone, wherein the controller is to determine respective displacements of the build platform to successively receive each of the plurality of layers of build material in the build zone during the build, wherein at least one of the respective displacements is based on data determined from a three-dimensional object obtained in a previous build.

Abstract: In an example, object model data representing at least a portion of an object defining an initial object geometry is received, wherein the object is to be generated by an additive manufacturing apparatus by fusing build material using a radiant heater. Based on a non-uniform radiant heating distribution of the additive manufacturing apparatus, a modified object geometry may be determined, wherein a local modification of the object geometry is determined based on a local radiant heating parameter determined from the non-uniform radiant heating distribution.

Abstract: In an example, a tangible machine-readable medium stores instructions which, when executed by a processor, cause the processor to evaluate a plurality of possible object generation arrangements based on a default separation distance and an enhanced separation distance, wherein the enhanced separation distance is used to assess predefined object sub-portions.

Abstract: In an example, a method includes generating a training dataset for an inference model to generate dimensional modifications to apply to object models to compensate for departures from model dimensions in objects generated using additive manufacturing based on those object models. Generating the training dataset may include acquiring, for each of a plurality of generated objects, (i) an indication of a first dimensional inaccuracy and a second dimensional inaccuracy, wherein the first and second dimensional inaccuracies are acquired in a direction of a first axis and relate to respective first and second object dimensions; and (ii) an indication of object placement within a fabrication chamber during object generation.

Abstract: Examples of additive manufacturing are described. In one example, a method comprises generating print data to cause application of fusing agent to a first region of a layer of build material of an object undergoing additive manufacturing, the first region corresponding to an inner region of an object undergoing additive manufacturing. The print data causes application of fusing agent and detailing agent to a second region of the layer, the second layer corresponding to a middle region of the object. The print data causes application of detailing agent to a third region of the layer, the third region corresponding to an outer layer of the object. Fusing energy is applied to the layer.

Abstract: In an example, a method includes receiving, at least one processor, object model data representing at least a portion of an object that is to be generated by an additive manufacturing apparatus by fusing build material within a fabrication chamber. An intended object placement location within the fabrication chamber may be determined, and a dimensional compensation to apply to the object model data may be determined using a mapping resource relating dimensional compensations to object placement locations. The determined dimensional compensation may be applied to the object model data to generate modified object model data using at least one processor.

Abstract: In an example, a method includes receiving, at at least one processor, object model data representing at least a portion of an object that is to be generated by an additive manufacturing apparatus by fusing build material within a fabrication chamber. At least one of a plurality of different geometrical compensation models to be applied to the object model data may be selected wherein the geometrical compensation models are to determine geometrical compensations to compensate for object deformation In additive manufacturing. An object generation operation based on a modification of the object model data using the or each selected geometrical compensation mode may be simulated and predicted attributes of the object when generated based on the or each simulation may be displayed.

Abstract: Examples of additive manufacturing are described. In one example, a method comprises generating print data to cause application of fusing agent to a first region of a layer of build material of an object undergoing additive manufacturing, the first region corresponding to an inner region of an object undergoing additive manufacturing. The print data causes application of fusing agent and detailing agent to a second region of the layer, the second layer corresponding to a middle region of the object. The print data causes application of detailing agent to a third region of the layer, the third region corresponding to an outer layer of the object. Fusing energy is applied to the layer.

Abstract: A method of configuring an additive manufacturing system. The method comprises configuring the additive manufacturing system with a first value of an operation parameter associated with the additive manufacturing system and, with the additive manufacturing system configured with the first value of the operation parameter, forming, in a build chamber, a first object The additive manufacturing system is subsequently configured with a second value of the operation parameter and, with the additive manufacturing system configured with the second value of the operation parameter, a second object is formed in the build chamber, subsequently to forming the first object. The method further includes receiving a signal indicative of which of the first value or the second value the operation parameter is to be configured with for subsequent operation of the additive manufacturing system.