Methods and apparatus for extracting profiles from three-dimensional images

Patent metadata

Field	Value
Publication number	US-11893744-B2
Application number	US-202117316417-A
Country	US
Kind code	B2
Filing date	May 10, 2021
Priority date	May 11, 2020
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

The techniques described herein relate to methods, apparatus, and computer readable media configured to determining a two-dimensional (2D) profile of a portion of a three-dimensional (3D) point cloud. A 3D region of interest is determined that includes a width along a first axis, a height along a second axis, and a depth along a third axis. The 3D points within the 3D region of interest are represented as a set of 2D points based on coordinate values of the first and second axes. The 2D points are grouped into a plurality of 2D bins arranged along the first axis. For each 2D bin, a representative 2D position is determined based on the associated set of 2D points. Each of the representative 2D positions are connected to neighboring representative 2D positions to generate the 2D profile.

First claim

The invention claimed is:

1. A computerized method for determining two-dimensional (2D) profiles of a portion of a three-dimensional (3D) point cloud of an object, the method comprising:
receiving data indicative of the 3D point cloud of the object comprising a plurality of 3D points;
determining a 3D region of interest in the 3D point cloud;
determining a plurality of different 3D subregions in the 3D region of interest, wherein each of the plurality of 3D subregions comprises a width along a corresponding first axis, a height along a corresponding second axis, and a depth along a corresponding third axis;
determining a plurality of sets of 3D points of the plurality of 3D points corresponding to the plurality of 3D subregions, wherein for each set of the plurality of sets of 3D points, each 3D point comprises a 3D location within the 3D subregion corresponding to the set of 3D points; and
for each set of the plurality of sets of 3D points:
representing the set of 3D points from three dimensions to only two dimensions as a set of 2D points based on coordinate values of the corresponding first and second axes of the set of 3D points;
grouping the set of 2D points into a plurality of 2D bins arranged along the corresponding first axis based on coordinate values of the corresponding first axis, wherein each 2D bin comprises a bin width;
determining, for each of the plurality of 2D bins, a representative 2D position based on the coordinate values of the corresponding second axis of the associated set of 2D points, wherein each representative 2D position includes associated coordinate values of the corresponding first and second axes; and
connecting each of the representative 2D positions to neighboring representative 2D positions to generate a 2D profile of the object along the corresponding first and second axes.

2. The method of claim 1 , further comprising, for each set of the plurality of sets of 3D points:
creating a 3D subregion coordinate system comprising the corresponding first axis, the corresponding second axis, and the corresponding third axis, wherein an origin of the 3D subregion coordinate system is disposed at a middle of the width and depth of the 3D subregion, and the height of the 3D subregion starts at the origin.

3. The method of claim 2 , further comprising, for each set of the plurality of sets of 3D points:
mapping points from a coordinate system of the 3D point cloud to the 3D subregion coordinate system.

4. The method of claim 1 , wherein representing the set of 3D points as the set of 2D points comprises representing the 3D points in a 2D plane comprising a first dimension equal to the width and a second dimension equal to the height, wherein the first dimension extends along the corresponding first axis and the second dimension extends along the corresponding second axis.

5. The method of claim 4 , wherein representing the set of 3D points as the set of 2D points comprises setting each value of the corresponding third axis of the set of 3D points to zero.

6. The method of claim 4 , wherein the plurality of 2D bins are arranged side-by-side along the corresponding first axis within the first dimension of the 2D plane.

7. The method of claim 1 , wherein determining a representative 2D position for each of the plurality of 2D bins comprises:
determining the set of 2D points of one or more 2D bins of the plurality of 2D bins is less than a threshold; and
setting the set of 2D points of the one or more 2D bins to an empty set.

8. The method of claim 1 , wherein determining the representative 2D position for each of the plurality of 2D bins comprises determining an average of the set of 2D points of each bin.

9. The method of claim 1 , wherein determining the representative 2D position for each of the plurality of 2D bins comprises selecting a 2D point of the associated set of 2D points with a maximum value of the corresponding second axis as the representative 2D position.

10. The method of claim 1 , wherein determining the representative 2D position for each of the plurality of 2D bins comprises, for each 2D bin:
grouping the set of 2D points into one or more clusters of 2D points with distances between values of the corresponding second axis of the 2D points of each cluster within a separation threshold, wherein distances between the values of the corresponding second axis of the 2D points of different clusters are greater than the separation threshold;
removing any clusters with less than a threshold minimum number of 2D points to generate a remaining set of one or more clusters;
determining a maximum cluster of the one or more remaining clusters comprising determining which of the one or more remaining clusters comprises a 2D point with a maximum coordinate along the corresponding second axis; and
averaging the 2D points of the maximum cluster to determine the representative 2D position.

11. The method of claim 1 , wherein determining the representative 2D position for each of the plurality of 2D bins comprises determining the representative 2D position only for 2D bins of the plurality of 2D bins with non-empty sets of 2D points.

12. The method of claim 1 , further comprising:
determining a surface defect of the object based, at least in part, on a successive sequence of 2D profiles of the 2D profiles generated for the plurality of sets of 3D points.

13. The method of claim 1 , further comprising:
determining a 3D feature of the object based, at least in part, on a series of 2D profiles of the 2D profiles generated for the plurality of sets of 3D points, the 3D feature of the object comprising at least one of a 3D perimeter line, a volume of at least a portion of the object, or an object defect.

14. The method of claim 1 , wherein receiving the data indicative of the 3D point cloud of the object comprises:
moving the object through a field of view of a camera; and
generating, via the camera, a digital image of the object passing through the field of view of the camera.

15. A non-transitory computer-readable media comprising instructions that, when executed by one or more processors on a computing device, are operable to cause the one or more processors to determine two-dimensional (2D) profiles of a portion of a three-dimensional (3D) point cloud of an object, comprising:
receiving data indicative of the 3D point cloud of the object comprising a plurality of 3D points;
determining a 3D region of interest in the 3D point cloud;
determining a plurality of different 3D subregions of interest in the 3D point cloud region of interest, wherein each of the plurality of 3D subregions of interest comprises a width along a corresponding first axis, a height along a corresponding second axis, and a depth along a corresponding third axis;
determining a plurality of sets of 3D points of the plurality of 3D points corresponding to the plurality of 3D subregions, wherein for each set of the plurality of sets of 3D points, each 3D point comprises a 3D location within the 3D region subregion of interest corresponding to the set of 3D points; and
for each set of the plurality of sets of 3D points:
representing the set of 3D points from three dimensions to only two dimensions as a set of 2D points based on coordinate values of the corresponding first and second axes of the set of 3D points;
grouping the set of 2D points into a plurality of 2D bins arranged along the corresponding first axis based on coordinate values of the corresponding first axis, wherein each 2D bin comprises a bin width;
determining, for each of the plurality of 2D bins, a representative 2D position based o

Assignees

• Cognex Corp

Inventors

• Zhu Hongwei
• Bogan Nathaniel
• Michael David J

Classifications

• G06T7/12 Primary

  Edge-based segmentation · CPC title

• G06F18/21345

  enforcing sparsity or involving a domain transformation · CPC title

• G06T17/00 Primary

  Three-dimensional [3D] modelling for computer graphics · CPC title

• G06T7/136

  involving thresholding · CPC title

• G06T2207/10028

  Range image; Depth image; 3D point clouds · CPC title