Methods and apparatus associated with three-dimensional objects are described. In an example, a method comprises receiving data representing a three-dimensional model object, the data comprising object model data and object property data. For at least one object property, a sub-region of the object in which the object property is non-variable is identified and, for at least one location within the object, all sub-regions in which the location is situated are identified. Based on the combination of identified sub-regions for a location, print material data is determined for the location. Control data for the production of a three-dimensional object is generated according to the print material data.

Methods and apparatus relating to substructures for 3D objects are described. In an example, a method for providing a three-dimensional halftone threshold matrix is described. The method may comprise receiving a substructure model representing a three-dimensional material structure and populating each location in the substructure model at which the structure exists with a halftone threshold value.

An exposure control device (31) serves for equipping and/or retrofitting a generative layer-wise building device (1). The latter comprises an exposure device (20) which emits electromagnetic radiation (22) or particle radiation and is configured to irradiate positions to be solidified in a layer in such a way that after cooling they exist as an object cross-section or part of the same. The exposure control device (31) has a first data output interface (36), at which control commands can be output to the exposure device (20). The control commands which are output specify one of a plurality of exposure types wherein an exposure type is defined by a predetermined combination of a radiation energy density to be emitted by the exposure device (20) and a scanning pattern with which the radiation (22) is being directed to a region of a layer of the building material (15). Furthermore, the exposure control device (31) has a second data output interface (37) at which an exposure type can be output in real time in relation to a timing of the output of a control command specifying this exposure type.

Methods and apparatus relating to substructures for three-dimensional objects are described. In an example, a method comprises receiving a lattice model having a consistent dimensionality and determining a substructure model representing a three-dimensional material structure, the substructure model being based on the lattice model and specifying a variable material distribution. The substructure model may be populated with halftone threshold data to provide a three-dimensional halftone threshold matrix

Adjustment of a halftoning threshold can, in an example implementation, include assigning a relative energy value, relative to a reference energy value, to a location of a build area and adjusting a halftoning threshold based on the relative energy value.

An alternative to additive manufacturing is disclosed, introducing an end-to-end workflow in which discrete building blocks are reversibly joined to produce assemblies called digital materials. Described is the design of the bulk-material building blocks and the devices that are assembled from them. Detailed is the design and implementation of an automated assembler, which takes advantage of the digital material structure to avoid positioning errors within a large tolerance. To generate assembly sequences, a novel CAD/CAM workflow is described for designing, simulating, and assembling digital materials. The structures assembled using this process have been evaluated, showing that the joints perform well under varying conditions and that the assembled structures are functionally precise.

A three-dimensional data generation device includes a data division unit, a detection unit, an output command unit, and a data correction unit. The data division unit divides sectional shape data on one layer of a shaped object into mark data for shaping a mark for correction of sectional shape data on a different layer to be output as superposed on the one layer and post-removal data obtained by removing the mark data from the sectional shape data on the one layer. The detection unit detects an amount of misregistration of the mark output using the mark data from a position determined in advance. The output command unit commands output using the post-removal data so as to form the one layer of the shaped object together with the mark. The data correction unit corrects the sectional shape data on the different layer using the amount of misregistration of the detected mark.

The invention relates to a method of determining toolpaths for an infill structure for a digital 3D model. The invention provides for a framework for planning toolpaths with control over the adaptive width for minimizing over- and underfill and introduce a beading scheme which reduces the bead width variation compared to the state of the art. We show that this framework supports various control schemes (so-called ‘beading schemes’) for determining the bead spacing and extrusion widths. Furthermore we present an approach to accurately realize adaptive bead width. The proposed method provides for a geometric framework allowing various adaptive bead width control schemes used to generate contour-parallel toolpaths which minimize under- and overfill.

A computing system may include an access engine and a toolpath reordering engine. The access engine may be configured to access an original layer toolpath for slice of a 3D CAD object as well as a heat criticality measure for the original layer toolpath. The heat criticality measure may specify a heat impact for different points on the multiple toolpath segments of the original layer toolpath for the 3D printing of the physical part using the original layer toolpath. The toolpath reordering engine may be configured to reorder the multiple toolpath segments into a modified layer toolpath, and the modified layer toolpath may have a heat criticality measure with a lesser heat impact on the physical part than the heat criticality measure for the original layer toolpath.

A method for determining a tonal vector for generating a control signal for a printing device includes providing a device-independent color value vector. The method includes transforming the device-independent color value vector into the tonal vector using a backward transformation. The method includes determining the backward transformation such that a cost function including an image difference metric term is minimized. The image difference metric term represents a difference between a reference image including device-independent color value vectors and a simulated image. The simulated image is determined by transforming an input image into a tonal image using the backward transformation and transforming the tonal image into the simulated image by using a forward transformation.