Method of Error Correction for 3D Imaging Device

• US 20140362184A1
• Filed: 06/07/2013
• Published: 12/11/2014
• Est. Priority Date: 06/07/2013
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Jovanovski, Brian L., Li, Jingquan
• Granted Patent: US 10,228,452 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A method is presented for correcting errors in a 3D scanner. Measurement errors in the 3D scanner are determined by scanning each of a plurality of calibration objects in each of a plurality of sectors in the 3D scanner'"'"'s field of view. The calibration objects have a known height, a known width, and a known length. The measurements taken by the 3D scanner are compared to the known dimensions to derive a measurement error for each dimension in each sector. An estimated measurement error is calculated based on scans of each of the plurality of calibration objects. When scanning target objects in a given sector, the estimated measurement error for that sector is used to correct measurements obtained by the 3D scanner.

Claims

1. A method of error correction for a 3D scanner, comprising:

providing a plurality of calibration objects each having a known height;

providing a 3D scanner having a field of view;

dividing at least a portion of the field of view into a plurality of sectors;

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a measured height corresponding to each of the plurality of sectors;

calculating a height measurement error for each of the plurality of sectors based on the known height of each calibration object and the measured height of each calibration object in each of the plurality of sectors; and

when scanning a target object positioned in a sector, calculating a corrected height measurement of the target object from the measured height of the target object and the height measurement error corresponding to the sector.

2. The method of claim 1, comprising storing the calculated height measurement error for each of the plurality of sectors in a memory store.

3. The method of claim 1, wherein each of the plurality of calibration objects has a known width, the method comprising:

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a measured width corresponding to each of the plurality of sectors;

calculating a width measurement error for each of the plurality of sectors based on the known width of each calibration object and the measured width of each calibration object in each of the plurality of sectors; and

when scanning a target object positioned in a sector, calculating a corrected width measurement of the target object from the measured width of the target object and the width measurement error corresponding to the sector.

4. The method of claim 1, wherein each of the plurality of calibration objects has a known length, the method comprising:

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a measured length corresponding to each of the plurality of sectors;

calculating a length measurement error for each of the plurality of sectors based on the known length of each calibration object and the measured length of each calibration object in each of the plurality of sectors; and

when scanning a target object positioned in a sector, calculating a corrected length measurement of the target object from the measured length of the target object and the length measurement error corresponding to the sector.

5. The method of claim 1, wherein each sector is located on a common horizontal plane.

6. The method of claim 5, wherein the horizontal plane is the ground plane.

7. A method of error correction for a 3D scanner, comprising:

providing a plurality of calibration objects each having a known height, known width, and known length;

providing a 3D scanner having a field of view;

dividing at least a portion of the field of view into a plurality of sectors;

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a measured height, a measured width, and a measured length corresponding to each of the plurality of sectors;

calculating a height measurement error for each of the plurality of sectors based on the known height of each calibration object and the measured height of each calibration object in each of the plurality of sectors;

calculating a width measurement error for each of the plurality of sectors based on the known width of each calibration object and the measured width of each calibration object in each of the plurality of sectors;

calculating a length measurement error for each of the plurality of sectors based on the known length of each calibration object and the measured length of each calibration object in each of the plurality of sectors; and

when scanning a target object positioned in a sector, calculating a corrected height measurement of the target object from the measured height of the target object and the height measurement error corresponding to the sector, calculating a corrected width measurement of the target object from the measured width of the target object and the width measurement error corresponding to the sector, and calculating a corrected length measurement of the target object from the measured length of the target object and the length measurement error corresponding to the sector.

8. The method of claim 7, wherein each sector is located on a common horizontal plane.

9. The method of claim 8, wherein the horizontal plane is the ground plane.

10. A method of error correction for a 3D scanner, comprising:

providing a plurality of calibration objects each having a first known dimension;

providing a 3D scanner having a field of view;

dividing at least a portion of the field of view into a plurality of sectors;

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a first measured dimension corresponding to each of the plurality of sectors;

for each sector, calculating a first dimension measurement error for each calibration object based on the first known dimension of the calibration object and the first measured dimension of the calibration object in the sector;

for each sector, determining if the first dimension measurement error for each calibration object is substantially the same;

for each sector, if the first dimension measurement error for each calibration object is substantially the same, storing the first dimension measurement error; and

when scanning a target object positioned in a sector, calculating a corrected first dimension measurement of the target object from the first measured dimension of the target object and the stored first dimension measurement error corresponding to the sector.

11. The method of claim 10, wherein the first known dimension is the object'"'"'s height and the first measured dimension is a height.

12. The method of claim 10, wherein the first known dimension is the object'"'"'s width and the first measured dimension is a width.

13. The method of claim 10, wherein the first known dimension is the object'"'"'s length and the first measured dimension is a length.

14. The method of claim 10, wherein each calibration object has a second known dimension orthogonal to the first known dimension, the method comprising:

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a second measured dimension corresponding to each of the plurality of sectors;

for each sector, calculating a second dimension measurement error for each calibration object based on the second known dimension of the calibration object and the second measured dimension of the calibration object in the sector;

for each sector, determining if the second dimension measurement error for each calibration object is substantially the same;

for each sector, if the second dimension measurement error for each calibration object is substantially the same, storing the second dimension measurement error; and

when scanning a target object positioned in a sector, calculating a corrected second dimension measurement of the target object from the second measured dimension of the target object and the stored second dimension measurement error corresponding to the sector.

15. The method of claim 14, wherein:

the first known dimension is the object'"'"'s height;

the first measured dimension is a height;

the second known dimension is the object'"'"'s width; and

the second measured dimension is a width.

16. The method of claim 14, wherein:

the first known dimension is the object'"'"'s height;

the first measured dimension is a height;

the second known dimension is the object'"'"'s length; and

the second measured dimension is a length.

17. The method of claim 14, wherein:

the first known dimension is the object'"'"'s width;

the first measured dimension is a width;

the second known dimension is the object'"'"'s length; and

the second measured dimension is a length.

18. The method of claim 10, wherein each calibration object has a second known dimension orthogonal to the first known dimension and a third known dimension orthogonal to the first known dimension and the second known dimension, the method comprising:

scanning with the 3D scanner each of the plurality of calibration objects, in successive fashion, in each of the plurality of sectors to obtain for each of the plurality of calibration objects a second measured dimension corresponding to each of the plurality of sectors and a third measured dimension corresponding to each of the plurality of sectors;

for each sector, calculating a second dimension measurement error for each calibration object based on the second known dimension of the calibration object and the second measured dimension of the calibration object in the sector;

for each sector, determining if the second dimension measurement error for each calibration object is substantially the same;

for each sector, if the second dimension measurement error for each calibration object is substantially the same, storing the second dimension measurement error;

for each sector, calculating a third dimension measurement error for each calibration object based on the third known dimension of the calibration object and the third measured dimension of the calibration object in the sector;

for each sector, determining if the third dimension measurement error for each calibration object is substantially the same;

for each sector, if the third dimension measurement error for each calibration object is substantially the same, storing the third dimension measurement error; and

when scanning a target object positioned in a sector, calculating a corrected second dimension measurement of the target object from the second measured dimension of the target object and the stored second dimension measurement error corresponding to the sector and calculating a corrected third dimension measurement of the target object from the third measured dimension of the target object and the stored third dimension measurement error corresponding to the sector.

19. The method of claim 18, wherein:

the first known dimension is the object'"'"'s height;

the first measured dimension is a height;

the second known dimension is the object'"'"'s width;

the second measured dimension is a width;

the third known dimension is the object'"'"'s length; and

the third measured dimension is a length.

20. The method of claim 10, wherein each sector is located on the ground plane.