Method of error correction for 3D imaging device

• US 10,228,452 B2
• Filed: 06/07/2013
• Issued: 03/12/2019
• 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
• Primary Examiner(s): Nasri, Maryam A
• Application Number:
  US13/912,262
• Publication Number:
  US 20140362184A1
• Time in Patent Office: 2,104 Days
• 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 three-dimensional calibration objects each having a known height, width and length, wherein no two calibration objects have the same shape, and wherein each calibration object is configured such that its height, width and length can be measured using a 3D scanner;

providing a 3D scanner having a field of view;

dividing the field of view into a plurality of sectors;

calculating a height measurement error for each of the plurality of sectors; and

calculating a corrected height measurement only for a target object positioned in a sector and scanned with the 3D scanner, the corrected height measurement being derived from both a measured height of the target object and the height measurement error corresponding to the sector in which the target object was positioned when scanned with the 3D scanner;

wherein calculating the height measurement error for a selected sector comprises the following substeps (a-d);

(a) positioning within the selected sector a calibration object that does not yet have a measured height associated with the selected sector;

(b) using the 3D scanner, scanning the positioned calibration object to obtain a measured height of the positioned calibration object, wherein the measured height is associated with the selected sector;

(c) repeating substeps (a) and (b) until each of the calibration objects has a measured height associated with the selected sector;

(d) for each calibration object, comparing the calibration object'"'"'s known height to the calibration object'"'"'s measured height associated with the selected 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, comprising:

calculating a width measurement error for each of the plurality of sectors; and

calculating a corrected width measurement for the target object, the corrected width measurement being derived from both a measured width of the target object and the width measurement error corresponding to the sector in which the target object was positioned when scanned with the 3D scanner;

wherein calculating the width measurement error for a selected sector comprises the following substeps (e-h);

(e) positioning within the selected sector a calibration object that does not yet have a measured width associated with the selected sector;

(f) using the 3D scanner, scanning the positioned calibration object to obtain a measured width of the positioned calibration object, wherein the measured width is associated with the selected sector;

(g) repeating substeps (e) and (f) until each of the calibration objects has a measured width associated with the selected sector;

(h) for each calibration object, comparing the calibration object'"'"'s known width to the calibration object'"'"'s measured width associated with the selected sector.

4. The method of claim 1, comprising:

calculating a length measurement error for each of the plurality of sectors; and

calculating a corrected length measurement for the target object, the corrected length measurement being derived from both a measured length of the target object and the length measurement error corresponding to the sector in which the target object was positioned when scanned with the 3D scanner;

wherein calculating the length measurement error for a selected sector comprises the following substeps (i-l);

(i) positioning within the selected sector a calibration object that does not yet have a measured length associated with the selected sector;

(j) using the 3D scanner, scanning the positioned calibration object to obtain a measured length of the positioned calibration object, wherein the measured length is associated with the selected sector;

(k) repeating substeps (i) and (j) until each of the calibration objects has a measured length associated with the selected sector;

(l) for each calibration object, comparing the calibration object'"'"'s known length to the calibration object'"'"'s measured length associated with the selected 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 three-dimensional calibration objects each having a known height, width and length, wherein no two calibration objects have the same shape, and wherein each calibration object is configured such that its height, width and length can be measured using a 3D scanner;

providing a 3D scanner having a field of view;

dividing the field of view into a plurality of sectors;

for each of the plurality of sectors, calculating a height measurement error, a width measurement error, and a length measurement error;

calculating a corrected height measurement only for a target object positioned in a sector and scanned with the 3D scanner, the corrected height measurement being derived from both a measured height of the target object and the height measurement error corresponding to the sector in which the target object was positioned when scanned with the 3D scanner;

calculating a corrected width measurement only for the target object, the corrected width measurement being derived from both a measured width of the target object and the width measurement error corresponding to the sector in which the target object was positioned when scanned with the 3D scanner; and

calculating a corrected length measurement only for the target object, the corrected length measurement being derived from both a measured length of the target object and the length measurement error corresponding to the sector in which the target object was positioned when scanned with the 3D scanner;

wherein calculating the height measurement error for a selected sector comprises the following substeps;

(a) positioning within the selected sector a calibration object that does not yet have a measured height associated with the selected sector;

(b) using the 3D scanner, scanning the positioned calibration object to obtain a measured height of the positioned calibration object, wherein the measured height is associated with the selected sector;

(c) repeating substeps (a) and (b) until each of the calibration objects has a measured height associated with the selected sector;

(d) for each calibration object, comparing the calibration object'"'"'s known height to the calibration object'"'"'s measured height associated with the selected sector;

wherein calculating the width measurement error for a selected sector comprises the following substeps (e-h);

(e) positioning within the selected sector a calibration object that does not yet have a measured width associated with the selected sector;

(f) using the 3D scanner, scanning the positioned calibration object to obtain a measured width of the positioned calibration object, wherein the measured width is associated with the selected sector;

(g) repeating substeps (e) and (f) until each of the calibration objects has a measured width associated with the selected sector;

(h) for each calibration object, comparing the calibration object'"'"'s known width to the calibration object'"'"'s measured width associated with the selected sector;

wherein calculating the length measurement error for a selected sector comprises the following substeps (i-l);

(i) positioning within the selected sector a calibration object that does not yet have a measured length associated with the selected sector;

(j) using the 3D scanner, scanning the positioned calibration object to obtain a measured length of the positioned calibration object, wherein the measured length is associated with the selected sector;

(k) repeating substeps (i) and (j) until each of the calibration objects has a measured length associated with the selected sector;

(l) for each calibration object, comparing the calibration object'"'"'s known length to the calibration object'"'"'s measured length associated with the selected 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 three-dimensional calibration objects each having a first known dimension, a second known dimension, and a third known dimension, wherein no two calibration objects have the same shape, and wherein each calibration object is configured such that its height, width and length can be measured using a 3D scanner;

providing a 3D scanner having a field of view;

dividing the field of view into a plurality of sectors;

for each calibration object, calculating a first dimension measurement error for each sector;

if all calculated first dimension measurement errors associated with a selected sector are equal, associating the first dimension measurement error with the selected sector and storing the first dimension measurement error in a memory store;

when scanning a target object positioned in a selected sector, calculating a corrected first dimension measurement only of the target object positioned in the selected sector based upon a first measured dimension of the target object and the stored first dimension measurement error associated with the selected sector;

wherein calculating the first dimension measurement error for a selected sector comprises the following substeps (a-d);

(a) positioning within the selected sector a calibration object that does not yet have a first measured dimension associated with the selected sector;

(b) using the 3D scanner, scanning the positioned calibration object to obtain a first measured dimension of the positioned calibration object, wherein the first measured dimension is associated with the selected sector;

(c) repeating substeps (a) and (b) until each of the calibration objects has a first measured dimension associated with the selected sector;

(d) for each calibration object, comparing the calibration object'"'"'s first known dimension to the calibration object'"'"'s first measured dimension associated with the selected 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, comprising:

for each calibration object, calculating a second dimension measurement error for each sector;

if all calculated second dimension measurement errors associated with a selected sector are equal, associating the second dimension measurement error with the selected sector and storing the second dimension measurement error in a memory store; and

when scanning a target object positioned in a selected sector, calculating a corrected second dimension measurement only of the target object positioned in the selected sector based upon a second measured dimension of the target object and the stored second dimension measurement error associated to the selected sector;

wherein calculating a second dimension measurement error for a selected sector comprises the following substeps (e-h);

(e) positioning within the selected sector a calibration object that does not yet have a second measured dimension associated with the selected sector;

(f) using the 3D scanner, scanning the positioned calibration object to obtain a second measured dimension of the positioned calibration object, wherein the second measured dimension is associated with the selected sector;

(g) repeating substeps (e) and (f) until each of the calibration objects has a second measured dimension associated with the selected sector;

(h) for each calibration object, comparing the calibration object'"'"'s second known dimension to the calibration object'"'"'s second measured dimension associated with the selected 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 14, comprising:

for each calibration object, calculating a third dimension measurement error for each sector;

if all calculated third dimension measurement errors associated with a selected sector are equal, associating the third dimension measurement error with the selected sector and storing the third dimension measurement error in a memory store; and

when scanning a target object positioned in a selected sector, calculating a corrected third dimension measurement only of the target object positioned in the selected sector based upon a third measured dimension of the target object and the stored third dimension measurement error associated to the selected sector;

wherein calculating a third dimension measurement error for a selected sector comprises the following substeps (i-l);

(i) positioning within the selected sector a calibration object that does not yet have a third measured dimension associated with the selected sector;

(j) using the 3D scanner, scanning the positioned calibration object to obtain a third measured dimension of the positioned calibration object, wherein the third measured dimension is associated with the selected sector;

(k) repeating substeps (i) and (j) until each of the calibration objects has a third measured dimension associated with the selected sector;

(l) for each calibration object, comparing the calibration object'"'"'s third known dimension to the calibration object'"'"'s third measured dimension associated with the selected 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.