THREE-DIMENSIONAL THRESHOLD MATRIX FOR THREE-DIMENSIONAL HALFTONING

• US 20170365095A1
• Filed: 04/16/2015
• Published: 12/21/2017
• Est. Priority Date: 04/16/2015
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: MOROVIC, Peter, MOROVIC, Jan, GONDEK, Jay S., GARCIA REYERO VINAS, Juan Manuel
• Granted Patent: US 10,445,929 B2
• Time in Patent Office: Days
• CPC Class Codes: B33Y 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: G06T 17/10 Constructive solid geometry [CSG] using solid primitives, e.g. cylinders, cubes
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels

Abstract

Certain examples described herein relate to a three-dimensional threshold matrix. The three-dimensional threshold matrix may be used for three-dimensional halftoning. In one example, values for a predefined two-dimensional threshold matrix are shifted with respect to a third dimension to provide the three-dimensional threshold matrix. In one example, the three-dimensional threshold matrix may then be processed in association with a digital representation of a three-dimensional object to output discrete material arrangement instructions for at least one production material. The instructions may be used to control an additive manufacturing system to produce the three-dimensional object.

Claims

1. An apparatus arranged to generate control data for production of a three-dimensional object comprising:

a halftone generator to apply a halftoning operation to a digital representation of at least a portion of the three-dimensional object,

the halftone generator being arranged to process the digital representation in association with a three-dimensional threshold matrix to output discrete material arrangement instructions for at least one production material;

a matrix generator to generate the three-dimensional threshold matrix for use by the halftone generator, the matrix generator being arranged to;

obtain values for a predefined two-dimensional threshold matrix; and

extend the two-dimensional threshold matrix into a third dimension to generate the three-dimensional threshold matrix by laterally-shifting, with respect to the third dimension and according to a defined sequence, subsequent matrices in a set of two-dimensional matrices, each matrix in the set of two-dimensional matrices comprising at least a subset of the values for the predefined two-dimensional threshold matrix.

2. The apparatus according to claim 1, comprising:

a deposit mechanism, communicatively coupled to the halftone generator, to deposit available production materials according to the discrete deposit instructions output by the halftone generator.

3. The apparatus according to claim 1,

wherein the digital representation of the three-dimensional object comprises at least one material volume coverage vector for at least one volume of the three-dimensional object,

wherein, for k materials available for production of the three-dimensional object and L discrete deposit states for said materials, the material coverage vector comprises L^k vector components, each vector component having an associated probability value, and

wherein the discrete deposit instructions comprises production instructions from a set of L*k available instruction values, each element at a production resolution having one of L deposit state instructions for each of said k materials.

4. The apparatus according to claim 1,

wherein the matrix generator is configured to determine lateral shift parameters for the set of two-dimensional matrices based on a complementarity metric for at least one of the set of two-dimensional matrices, and

wherein the complementarity metric compares a production material placement associated with a given two-dimensional matrix with a production material placement for matrices below the given two-dimensional matrix in the set of two-dimensional matrices.

5. The apparatus according to claim 1, wherein the defined sequence comprises at least one of:

a random walk in the third dimension;

a defined set of lateral shift parameters for each matrix in the set of two-dimensional matrices; and

a set of points on an analytic curve in the third dimension with variation in a first and second dimension.

6. The apparatus according to claim 1, wherein the predefined two-dimensional threshold matrix comprises one of:

a void-and-cluster matrix;

an amplitude modulation (AM) matrix; and

a noise matrix having a predefined color.

7. The apparatus according to claim 1,

wherein the matrix generator is arranged to obtain an object property associated with the three-dimensional object and to select the defined sequence based on the obtained object property,

the defined sequence implementing a structure of the three-dimensional object that contributes to the object property.

8. A computer-implemented method for generating a three-dimensional halftone threshold matrix for use in production of a three-dimensional object, comprising:

loading data comprising values for a halftone threshold matrix in two dimensions;

generating a set of sub-matrices in the two-dimensions based on values from the halftone threshold matrix, including;

processing values for the set of sub-matrices to introduce a lateral shift between subsequent sub-matrices in the set, the lateral shift being in at least one of said two dimensions; and

generating a three-dimensional halftone threshold matrix for use in production of a three-dimensional object by combining the processed values for the set of sub-matrices in a third dimension,

wherein the processed values for each sub-matrix represent halftone threshold values for application to a section of a digital representation corresponding to a layer of the three-dimensional object.

9. The method of claim 8, comprising:

obtaining a digital representation for the three-dimensional object;

halftoning the digital representation using the three-dimensional halftone threshold matrix to generate control data for production of the three-dimensional object; and

producing the three-dimensional object on an additive manufacturing system using the generated control data.

10. The method of claim 9, wherein values for the set of sub-matrices are processed in dependence on the obtained digital representation, such that the generation of the three-dimensional halftone threshold matrix is performed after obtaining the digital representation but before halftoning and production of the three-dimensional object.

11. The method of claim 8, wherein processing values for the set of sub-matrices comprises:

generating a first sub-matrix in the set of sub-matrices using the data comprising at least a subset of values for the halftone threshold matrix, the first sub-matrix being associated with a first z-axis value for the three-dimensional halftone threshold matrix;

determining lateral shift parameters for a second sub-matrix, the second sub-matrix being associated with a second z-axis value for the three-dimensional halftone threshold matrix, the lateral shift parameters comprising a first shift parameter for a transformation in relation to an x-axis and a second shift parameter for a transformation in relation to an y-axis; and

generating the second sub-matrix by shifting the values for the halftone threshold matrix in each of the two dimensions of said sub-matrix based on the lateral shift parameters.

12. The method of claim 10, wherein determining lateral shift parameters comprises:

determining lateral shift parameters according to a desired structure for the three-dimensional object.

13. The method of claim 8, wherein the lateral shift between subsequent sub-matrices is performing according to one of:

a random walk in the third dimension;

a defined set of lateral shift parameters for each sub-matrix; and

a set of points on an analytic curve in a third dimension with variation in a first and second dimension.

14. The method of claim 8, wherein the halftone threshold matrix comprises one of:

a void-and-cluster matrix;

an amplitude modulation (AM) matrix; and

a noise matrix having a predefined color.

15. An electronic data structure for use in three-dimensional halftoning comprising:

data values defined in association with a plurality of co-ordinates in three-dimensional space, the co-ordinates representing a grid resolution in x, y and z dimensions,

wherein the data values comprise threshold values for a three-dimensional halftone operation and are representative of a plurality of z-dimension planes arranged parallel to the x and y dimensions,

wherein each set of data values associated with a z-dimension plane comprise at least a subset of data values from a predefined two-dimensional halftone threshold matrix, and

wherein data values associated with at least one z-dimension plane comprise data values from the predefined two-dimensional halftone threshold matrix that are shifted in one or more of the x and y dimensions.