Scene change detection in a dimensioner

• US 9,940,721 B2
• Filed: 06/10/2016
• Issued: 04/10/2018
• Est. Priority Date: 06/10/2016
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Lloyd, Ryan Andrew, McCloskey, Scott
• Primary Examiner(s): Dang, Duy M
• Application Number:
  US15/179,327
• Publication Number:
  US 20170358098A1
• Time in Patent Office: 669 Days
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 21/042 Calibration or calibration artifacts G01B3/30, G01B9/02072 take precedence
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/50 Depth or shape recovery
• CPC Class Codes: G07B 17/00661 Sensing or measuring mailpieces weighing G01G19/00
• CPC Class Codes: G07B 2017/00685 Measuring the dimensions of mailpieces

Abstract

A package dimensioner is disclosed. A change in the pose of the package dimensioner is detected by background modeling the area of a measurement platform and then determining if a number of points in a scene are different in distance from the background model. Change in the pose can also be detected by comparing a count of support points in a 3D container generated from images taken in a training process with a count of support points in a subsequent images and determining how many support points are different.

Claims

1. A method, comprising:

initializing a dimensioning system by;

at a range camera, capturing one or more initial reference images of a measurement platform and surrounding area;

at a processor;

generating a reference depth map from each initial reference image;

generating and storing to a memory a background model from the reference depth maps;

testing the dimensioning system for a scene change by;

at the range camera, capturing a subsequent image of the measurement platform and surrounding area;

at the processor;

generating a current depth map from the subsequent image;

comparing each pixel of the current depth map with a corresponding pixel of the background model; and

counting a number of pixels Pv of the current depth map that differ absolutely from the background model by more than the prescribed threshold THRESH1, and if the number of pixels Pv is greater than a threshold THRESH2, determining that a significant change in the image has occurred.

2. The method according to claim 1, where the testing is carried out on a periodic basis.

3. The method according to claim 1, further comprising executing a dimensioning process to measure the dimensions of an object on the measurement platform.

4. The method according to claim 3, where the testing is carried out whenever a prescribed period of inactivity in measuring dimensions of an object on the measurement platform.

5. The method according to claim 3, where the testing is carried out prior to each measurement of dimensions of an object on the measurement platform.

6. The method according to claim 1, further comprising generating an alert upon determining that a significant scene change has occurred.

7. The method according to claim 1, further comprising upon determining that a significant scene change has occurred, repeating the initializing.

8. A dimensioning system, comprising:

a measurement platform;

a range camera mounted so as to capture an image of the measurement platform and surrounding area;

a processor programmed to carry out the following actions;

initialize the dimensioning system by;

receiving one or more initial reference images of the measurement platform and surrounding area from the range camera;

generating and storing to a memory a background model from the one or more captured initial reference images;

test the dimensioning system for a scene change by;

receiving a subsequent image of the platform area from the range camera;

generating a current depth map from the subsequent image;

comparing each pixel of the current depth map with a corresponding pixel of the background model; and

counting a number of pixels Pv of the current depth map that differ absolutely from the background model by more than the prescribed threshold THRESH1, and if the number of pixels Pv is greater than a threshold THRESH2, determining that a significant change in the image has occurred.

9. The system according to claim 8, where the testing is carried out on a periodic basis.

10. The system according to claim 8, further comprising the processor executing a dimensioning process to measure dimensions of an object on the measurement platform.

11. The system according to claim 10, where the testing is carried out whenever a prescribed period of inactivity in measuring dimensions of an object on the measurement platform.

12. The system according to claim 10, where the testing is carried out prior to each measurement of dimensions of an object on the measurement platform.

13. The system according to claim 8, further comprising the processor generating an alert upon determining that a significant scene change has occurred.

14. The system according to claim 8, further comprising upon determining that a significant scene change has occurred, the processor repeating the initializing.

15. A method, comprising:

initializing a dimensioning system by;

at a range camera, capturing an initial reference image of a platform and surrounding area;

at a processor, generating a three-dimensional container around the platform and storing the container to memory; and

at the processor, determining a count of support points in the container from the initial reference image;

testing the dimensioning system for a scene change by;

at the range camera, capturing a subsequent image of the measurement platform and surrounding area;

at the processor;

counting support points in the subsequent image that are in the container;

comparing the count of support points in the container in the subsequent image with the count of support points in the container in the initial reference image;

based on the comparison, determining if a prescribed difference in the counts is present; and

upon determining that a prescribed difference in the counts exists establishing that a significant scene change has occurred.

16. The method according to claim 15, where the testing is carried out on a periodic basis.

17. The method according to claim 15, further comprising executing a dimensioning process to measure dimensions of an object on the platform.

18. The method according to claim 17, where the testing is carried out whenever a prescribed period of inactivity in measuring dimensions of an object on the measurement platform.

19. The method according to claim 17, where the testing is carried out prior to each measurement of dimensions of an object on the measurement platform.

20. The method according to claim 17, further comprising generating an alert upon determining that a significant scene change has occurred.

21. The method according to claim 17, where the container comprises a right prism with a base approximating a convex polygon, where the base is parallel to a congruent convex polygon that bounds the measurement platform, and where the prism'"'"'s height equals twice a maximum support distance.

22. The method according to claim 15, where the container comprises a right cylinder with a circular base, where the base is parallel to a congruent circle that bounds the measurement platform, and where the cylinder'"'"'s height equals twice the maximum support distance.

23. The method according to claim 15, comprising:

when a significant scene change is deemed to have occurred, searching the scene for the measurement platform at a location coplanar therewith.

24. The method according to claim 15, further comprising upon establishing that a significant scene change has occurred, repeating the initializing.

25. A dimensioning system, comprising:

a measurement platform;

a range camera mounted so as to capture an image of the measurement platform and surrounding area;

a processor programmed to carry out the following actions;

initialize the dimensioning system by;

receiving an initial reference image of a platform area from the range camera;

generating a three-dimensional container around the measurement platform and storing the container to memory; and

determining a count of support points in the container from the initial reference image;

test the dimensioning system for a scene change by;

receiving a subsequent image of the measurement platform and surrounding area from the range camera;

counting support points in the subsequent image that are in the container;

comparing the count of support points in the container in the subsequent image with the count of support points in the container in the initial reference image;

based on the comparison, determining if a prescribed difference in the counts of support points is present; and

upon determining that a prescribed difference in the counts exists establishing that a significant scene change has occurred.

26. The system according to claim 25, where the testing is carried out on a periodic basis.

27. The system according to claim 25, further comprising the processor executing a dimensioning process to measure dimensions of an object on the measurement platform.

28. The system according to claim 27, where the testing is carried out whenever a prescribed period of inactivity in measuring dimensions of an object on the measurement platform.

29. The system according to claim 27, where the testing is carried out prior to each measurement of dimensions of an object on the measurement platform.

30. The system according to claim 25, further comprising the processor generating an alert upon determining that a significant scene change has occurred.

31. The system according to claim 25, where the container comprises a right prism with a base approximating a convex polygon, where the base is parallel to a congruent convex polygon that bounds the measurement platform, and where the prism'"'"'s height equals twice the maximum support distance.

32. The system according to claim 25, where the container comprises a right cylinder with a circular base, where the base is parallel to a congruent circle that bounds the measurement platform, and where the cylinder'"'"'s height equals twice the maximum support distance.

33. The system according to claim 25, further comprising when a significant scene change is deemed to have occurred, the processor searching the scene for the measurement platform at a location coplanar therewith.

34. The system according to claim 25, further comprising the processor repeating the initializing upon establishing that a significant scene change has occurred.