Abstract: In one example in accordance with the present disclosure, a system is described. The system includes a model generator that includes a processor and memory. The model generator obtains an input that indicates a property of a conductive element to be printed and obtains a template which defines a lattice structure for the conductive element. The model generator also generates a latticed conductive element model based on the template and the input. The system also includes a three-dimensional printing controller to trigger selective hardening of build material to form the latticed conductive element.

Abstract: Examples of methods for fiducial location are described herein. In some examples, a method may include estimating a first location of an unidentified fiducial based on image coordinates and grid coordinates of a set of contiguous fiducials. In some examples, the method may include determining that a candidate fiducial is a fiducial based on comparing the first location with a second location of the candidate fiducial.

Abstract: Examples of methods for fiducial pattern detection are described herein. In some examples, a method may include detecting fiducial pattern subsets in image subsets of an image of an object. In some examples, the method may also include selecting a first image subset that includes a largest first fiducial pattern subset. In some examples, the method may further include extending the first fiducial pattern subset from the first image subset to a neighboring second image subset.

Abstract: An example non-transitory computer-readable medium includes instructions to generate a linear pattern of contrasting elements. The linear pattern encodes scannable information. The instructions are further to generate shifted instances of the linear pattern, a shifted instance being shifted with respect to the linear pattern along a length of the linear pattern. The instructions are further to form an array of the shifted instances of the linear pattern orthogonal to the length of the linear pattern to generate a two-dimensional pattern of the contrasting elements. The two-dimensional pattern repeatedly encodes the scannable information.

Abstract: In some examples, a method for recovering an alignment grid comprising multiple fiducial dots, the alignment grid for resolving multiple data dots, comprises determining a respective local structure within a local region around each fiducial dot and each data dot, and generating a connected subset of local structures to form a candidate alignment grid.

Abstract: A method of forming a data-hiding watermark on a surface may include encoding data within an image using the chrominance data of the of the image, adjusting at least one characteristic of the image to enhance the prominence of the encoded data within the image, and printing the adjusted, encoded image onto the surface.

Abstract: Examples of methods for three-dimensional object marking are described herein. In some examples, a method may include determining a set of volumes based on a one-dimensional (1D) barcode. In some examples, the method may include overlapping the set of volumes with a voxel representation of a three-dimensional (3D) object. In some examples, the method may include marking voxels of the 3D object that are within the set of volumes.

Abstract: In an example method, a first dot pattern of shadow dots and second dot pattern of highlight dots is generated. The first dot pattern and second dot pattern include information to be encoded across the image. The first dot pattern and the second dot pattern are mapped to a corresponding subset of the greyscale source pixels, the greyscale source pixels corresponding to an image to be printed. A value of a greyscale pixel in the subset of the greyscale source pixels is modified based on a predetermined threshold pixel value. The value of the greyscale pixel is set to a highlight dot value in response to detecting that the predetermined threshold pixel value is exceeded or set to a shadow dot value in response to detecting that the predetermined threshold value is not exceeded. The image including the subset of pixels with modified values is printed.

Abstract: Examples disclosed herein relate to determining image capture position information based on a quasi-periodic pattern. For example, a processor may determine whether a target area is within a captured image based on the detection of a quasi-periodic pattern in a first detection area and in a second detection area of the captured image.

Abstract: According to an example, density rank matrix normalization for three dimensional printing may include receiving a density rank matrix. The density rank matrix may include elements that include rank values, and the rank values may specify an order by which a voxel is to be turned on to generate an output object. A normalization specification of maximum and minimum structure sizes for structures that are to form the output object may be received. Further, each of the rank values may be converted, according to the normalization specification, to a corresponding threshold value to generate a density threshold matrix.

Abstract: In an example method, a visually significant marking scheme is generated including a pattern of data marks and reference marks based on a received image to be printed, data information, and reference information. Data marks are generated based on the data information and the reference marks are generated based on the reference information. The image is printed including the data marks and the reference marks arranged based on the visually significant marking scheme onto the surface of the object.

Abstract: In an example method, a first dot pattern of shadow dots and second dot pattern of highlight dots is generated. The first dot pattern and second dot pattern include information to be encoded across the image. The first dot pattern and the second dot pattern are mapped to a corresponding subset of the greyscale source pixels, the greyscale source pixels corresponding to an image to be printed. A value of a greyscale pixel in the subset of the greyscale source pixels is modified based on a predetermined threshold pixel value. The value of the greyscale pixel is set to a highlight dot value in response to detecting that the predetermined threshold pixel value is exceeded or set to a shadow dot value in response to detecting that the predetermined threshold value is not exceeded. The image including the subset of pixels with modified values is printed.

Abstract: One example includes a three-dimensional (3D) printed object including a first lattice structure and a second lattice structure. The first lattice structure includes a first matrix having a first length, a first width, and a first height. The second lattice structure includes a second matrix having a second length, a second width, and a second height. The second length times two is a factor of the first length, the second width times two is a factor of the first width, and the second height times two is a factor of the first height.

Abstract: A data-bearing medium is disclosed. The data-bearing medium includes a section of cells having a set of opposite-shifted clusters. The cells include a combination of opposite shifts of the set of opposite-shifted clusters, which represent a single value.

Abstract: An example system in accordance with an aspect of the present disclosure includes a halftone engine and a gray value engine. The halftone engine is to apply halftoning to an image recursively across a plurality of levels of image scales and spatial resolutions, to generate a pattern that is at least quasi-periodic across the plurality of levels. The gray value engine is to substitute gray values recursively for at least a portion of the halftoning.

Abstract: A method of forming a data-hiding watermark on a surface may include encoding data within an image using the chrominance data of the of the image, adjusting at least one characteristic of the image to enhance the prominence of the encoded data within the image, and printing the adjusted, encoded image onto the surface.

Abstract: In an example method, a set of source pixels corresponding to an image to be printed and a dot pattern of pixels including information to be encoded across the image are received. The dot pattern of pixels is mapped to a corresponding subset of the source pixels. A value of a clipping channel color in the subset of the source pixels is modified based on an original value of the clipping channel color for each pixel in the subset. The clipping channel color is used to detect the dot pattern of pixels. The image including the subset of pixels with modified clipping channel colors is printed.

Abstract: According to an example, density rank matrix normalization for three dimensional printing may include receiving a density rank matrix. The density rank matrix may include elements that include rank values, and the rank values may specify an order by which a voxel is to be turned on to generate an output object. A normalization specification of maximum and minimum structure sizes for structures that are to form the output object may be received. Further, each of the rank values may be converted, according to the normalization specification, to a corresponding threshold value to generate a density threshold matrix.

Abstract: According to an example, density rank matrix generation for three-dimensional printing may include determining dimensions of a density rank matrix based on a skeleton line specification of a lattice structure and a density rank matrix size specification. A number of elements of the density rank matrix may be determined based on the dimensions of the density rank matrix. The elements may be sorted based on an analysis of a property of each of the elements relative to the lattice structure. The density rank matrix may be generated based on the sorting of the elements.

Abstract: An omnidirectional barcode may include a graphical representation of a one-dimensional barcode wherein the graphical representation of the one-dimensional barcode is extended circumferentially around a three-dimensional (3D) object. A method of forming an omnidirectional barcode may include creating a graphical representation of a one-dimensional barcode and extending the one-dimensional representation in at least one dimension.