Abstract: In an example, a method includes forming a first layer of build material to be processed in object generation and selectively applying at least one print agent on to the first layer based on a print instruction for the first layer. Energy may be applied to the first layer to cause fusion in at least a region thereof, and at least one temperature associated with a thermal contribution of the first layer to a subsequent layer of build material to be processed in object generation may be measured. It may be determined if a temperature condition indicative of a departure from an anticipated thermal contribution of the first layer to a region of subsequent layer exists. If such a temperature condition does exist, a print instruction for applying print agent to the region of the subsequent layer based on the temperature condition may be determined.

Abstract: According to one aspect, there is provided an apparatus and a method for extracting 3D printed parts from a build unit (114) in cleaning station comprising obtaining data representing the contents of a print job contained in the build unit (114) and generating a visualization of the contents of the build unit (114) based in part on the obtained data and in part on data related to operations performed by the cleaning station.

Abstract: According to an example, a 3D printer may include a delivery device and a controller. The controller may access a morphology of a part to be formed from a plurality of build materials in a layer, determine, based upon the accessed morphology, a first delivery pattern for the delivery device to selectively deliver liquid droplets onto build materials in the layer during a first pass over the layer and a second delivery pattern for the delivery device to selectively deliver liquid droplets onto build materials in the layer during a second pass over the layer to control a property of the part formed of some of the build materials in the layer. The controller may also control the delivery device to selectively deliver liquid droplets onto build materials in the layer according to the determined first and second delivery patterns respectively during the first pass and the second pass.

Abstract: According to one aspect there is provided a three-dimensional printer. The printer comprises a controller to obtain data relating to a layer of a build model, to process non-empty layers according to a first operating mode and to process empty layers according to a second operating mode.

Abstract: In an example, a method of controlling an additive manufacturing apparatus to generate a three dimensional object comprises processing successive layers of build material so as to form successive layers of a three dimensional object, wherein the processing of each layer is performed within a predetermined layer processing time by a plurality of components. The method may further include selecting, by at least one processor, from a plurality of ancillary tasks, at least one ancillary task to be performed in relation to at least one component of the plurality of components. The method may further include scheduling, by at least one processor, the at least one ancillary task to be performed in relation to the at least one component within the predetermined layer processing time for a single layer or for multiple layers of the build material.

Abstract: In some examples, an agent distributor may be to selectively deliver agent through nozzles of the agent distributor to portions of layers of build material in patterns derived from agent delivery control data representing slices of a three-dimensional object such that the portions are to solidify to form the slices in accordance with the patterns. While generating the three-dimensional object, the agent distributor may be primed such that a particle of the build material is removed from the agent distributor through at least one of the nozzles.

Abstract: There is provided a method and apparatus for controlling heat to a build surface. A thermal profile over the build surface is determined. The determined thermal profile over the build surface is compared with an expected thermal profile over the build surface. Based on the comparison, the determined thermal profile over the build surface or the expected thermal profile over the build surface is selected to control an amount of heat provided by a heating module to the build surface.

Abstract: An agent distributor may be to selectively deliver agent at a first contone density and at a second contone density different from the first contone density respectively onto an interior portion and a surface portion of successive layers of build material in respective first and second patterns in accordance with data representing a three-dimensional object to be generated, so that the build material is to solidify to form slices of the three-dimensional object in accordance with the first and second patterns, and so that the three-dimensional object is to achieve a target surface roughness as a result of the second contone density of the second pattern.

Abstract: Temperatures of a layer of build material on a support member may be detected. Each of the temperatures corresponding to a respective area of the layer. Based on data representing the three-dimensional object, a subset of the temperatures may be filtered from spatial temperature distribution data comprising the temperatures. A degree of heat or energy applied to the layer may be controlled based on the filtered spatial temperature distribution data.

Abstract: According to one example, there is provided a method of 3D printing. The method comprises generating, within a volume of build material, a volume of solidified build material, and marking a predetermined portion of unsolidified build material within the build volume with a marking agent.

Abstract: According to one example, there is provided a method, in a three-dimensional printing system (100), of determining the thickness of a layer of build material formed on a build platform (104). The method comprises forming a layer of build material (402) on a base having predetermined color characteristics, measuring color characteristics of the deposited layer of build material, and determining, based on the measured color characteristics, the thickness of at least a portion of the formed layer of build material.

Abstract: According to one example, there is provided a printing system. The printing system comprises a support having a plurality of spaced apertures and a colour sensor moveable to measure light from each aperture. The printing system further comprises a controller to control the colour sensor to measure characteristics of light emitted through each aperture, and to determine, for each aperture, light calibration data.

Abstract: In an example, a method includes receiving, at a processor, data representing a three dimensional object. Using the processor, a modified data representation of the three dimensional object may be determined wherein, in the modified data representation, the three dimensional object is represented in terms of homogenous sub-volumes. Each homogenous sub-volume is homogenous with respect to a predetermined attribute and contains locations which are within a common object boundary distance band of plurality of object boundary distance bands, wherein at least two object boundary distance bands partially overlap.

Abstract: According to one example, there is provided a printing system. The printing system comprises a support having a plurality of spaced apertures and a color sensor moveable to measure light from each aperture. The printing system further comprises a controller to control the color sensor to measure characteristics of light emitted through each aperture, and to determine, for each aperture, light calibration data.

Abstract: In some examples, an agent distributor may be to selectively deliver agent through nozzles of the agent distributor to portions of layers of build material in patterns derived from agent delivery control data representing slices of a three-dimensional object such that the portions are to solidify to form the slices in accordance with the patterns. While generating the three-dimensional object, the agent distributor may be primed such that a particle of the build material is removed from the agent distributor through at least one of the nozzles.

Abstract: Image processing transforms input multi-level image data into output image data having a smaller number of levels (the input and output image data represents images formed of cells). The image processing distributes quantization error of a target cell of the image to neighbor cells in proportions determined by a set of weights. The distribution excludes neighbor cells whose data level is less than a threshold value from receiving distributed quantization error, or allows just a fraction of the quantization error to be distributed to such neighbor cells.

Abstract: A method for determining a parameter of a process associated with a 3D printing process provided. A first amount corresponding to an object of fused powder surrounded by non-fused powder is used. The first amount is separated into a second amount of non-fused powder and a third amount corresponding to the object including residual powder material attached. The residual powder material is removed from the object using a fourth amount of a cleaning agent. A fifth amount corresponding to the fused powder of the cleaned object and a sixth amount of material corresponding to a mixture of the removed residual powder material and the cleaning agent is obtained. The mixture includes a seventh amount of material being recovered, an eighth amount of material corresponding to powder material wastage, and the fourth amount. The parameter is derived from at least two of first to eighth amounts of material.

Abstract: According to one example, there is provided a method of determining characteristics of a build material. The method comprises obtaining a first quantity of a first build material, determining, for the first build material, the proportion of non-marked build material and marked build material, determining, based on the determined proportion, a first quantity of the first build material to be combined with a second quantity of a second build material to produce a third quantity of mixed build material having a predetermined proportion of marked build material.

Abstract: A method of fabricating a three dimensional object in an additive layer manufacturing process, e.g. 3D printing, wherein a three dimensional design of the three dimensional object is modelled as a plurality of three dimensional pixels or vortexes. For every pixel or vortex, at least one parameter is calculated and is used to select a setting for use when fabricating the three dimensional object. The parameter may be a speed or rate at which heat will diffuse away from the pixel or vortex, or a weighted density surrounding the pixel or vortex. The method provides higher quality fabrication of the three dimensional object.

Abstract: A method of calibrating an apparatus for generating a three-dimensional object is described in which a calibration substrate is generated by depositing build material and applying energy to the build material to form a fused surface; a calibration pattern is generated on the calibration substrate by depositing an agent on the calibration surface according to a predetermined pattern; and an attribute of the calibration pattern is measured.