THREE-DIMENSIONAL COORDINATE SCANNER AND METHOD OF OPERATION

• US 20140268093A1
• Filed: 06/18/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Bridges, Robert E., Tohme, Yazid, Pfeffer, Charles
• Granted Patent: US 9,041,914 B2
• Time in Patent Office: Days
• US Class Current: 356/3.08
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 11/2531 using several gratings, projected with variable angle of incidence on the object, and one detection device
• CPC Class Codes: G01B 21/045 Correction of measurements G01B9/02055 takes precedence
• CPC Class Codes: G01B 5/004 for measuring coordinates of points
• CPC Class Codes: G01C 3/10 using a parallactic triangle with variable angles and a base of fixed length in the observation station, e.g. in the instrument
• CPC Class Codes: G01S 17/003 Bistatic lidar systems; Multistatic lidar systems
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G06T 2200/04 involving 3D image data
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 7/593 from stereo images
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: H04N 13/204 using stereoscopic image cameras stereoscopic photography G03B35/00
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/275 from 3D object models, e.g. computer-generated stereoscopic image signals

Abstract

A noncontact optical three-dimensional measuring device that includes a projector, a first camera, and a second camera; a processor electrically coupled to the projector, the first camera and the second camera; and computer readable media which, when executed by the processor, causes the first digital signal to be collected at a first time and the second digital signal to be collected at a second time different than the first time and determines three-dimensional coordinates of a first point on the surface based at least in part on the first digital signal and the first distance and determines three-dimensional coordinates of a second point on the surface based at least in part on the second digital signal and the second distance.

Claims

1. A noncontact optical three-dimensional measuring device comprising:

an assembly that includes a projector, a first camera, and a second camera, wherein the projector, the first camera, and the second camera are fixed in relation to one another, there being a first distance between the projector and the first camera and a second distance between the projector and the second camera, the projector having a light source, the projector configured to emit onto a surface of an object a first light having any of a plurality of patterns, the first camera having a first lens and a first photosensitive array, the first camera configured to receive a first portion of the first light reflected off the surface and to produce a first digital signal in response, the first camera having a first field of view, the first field of view being a first angular viewing region of the first camera, the second camera having a second lens and a second photosensitive array, the second camera configured to receive a second portion of the first light reflected off the surface and to produce a second digital signal in response, the second camera having a second field of view, the second field of view being a second angular viewing region of the second camera, the second field of view being different than the first field of view; and

a processor, electrically coupled to the projector, the first camera, and the second camera, that executes a computer executable program code that when executed by the processor performs operations that include causing the first digital signal to be collected at a first time and the second digital signal to be collected at a second time different than the first time, determining three-dimensional coordinates of a first point on the surface based at least in part on the first digital signal and the first distance, and determining three-dimensional coordinates of a second point on the surface based at least in part on the second digital signal and the second distance.

2. The noncontact optical three-dimensional measuring device of claim 1 wherein the computer executable program code causes the projector to produce the first light having a first pattern from among the plurality of patterns and the first camera to produce in response the first digital signal and further causes the projector to produce the first light having a second pattern from among the plurality of patterns and the second camera to produce in response the second digital signal.

3. The noncontact optical three-dimensional measuring device of claim 2 wherein the first pattern is a spatially varying pattern.

4. The noncontact optical three-dimensional measuring device of claim 3 wherein the first pattern includes at least three non-collinear pattern elements.

5. The noncontact optical three-dimensional measuring device of claim 4 wherein the second pattern is a spatially varying pattern that includes at least three non-collinear pattern elements.

6. The noncontact optical three-dimensional measuring device of claim 5 wherein the second pattern is a line pattern.

7. The noncontact optical three-dimensional measuring device of claim 6 wherein the second pattern is a line pattern that is swept in time.

8. The noncontact optical three-dimensional measuring device of claim 6 wherein the second pattern is a spot of light that is swept in time.

9. The noncontact optical three-dimensional measuring device of claim 1 wherein the first field of view is at least twice as large as the second field of view.

10. The noncontact optical three-dimensional measuring device of claim 1 wherein the first photosensitive array includes a first pixel, the first pixel configured to capture light reflected off a first area of the surface, the second photosensitive array includes a second pixel, the second pixel configured to capture light reflected off a second area of the surface, wherein the second area is smaller than the first area.

11. The noncontact optical three-dimensional measuring device of claim 4 wherein the first pattern is a temporally varying pattern.

12. A method of determining three-dimensional coordinates on a surface of an object, the method comprising:

providing an assembly that includes a projector, a first camera, and a second camera, wherein the projector, the first camera, and the second camera are fixed in relation to one another, there being a first distance between the projector and the first camera and a second distance between the projector and the second camera, the projector having a light source, the projector configured to emit onto the surface a first light having any of a plurality of patterns, the first camera having a first lens and a first photosensitive array, the first camera configured to receive a first portion of the first light reflected off the surface, the first camera having a first field of view, the first field of view being a first angular viewing region of the first camera, the second camera having a second lens and a second photosensitive array, the second camera configured to receive a second portion of the first light reflected off the surface, the second camera having a second field of view, the second field of view being a second angular viewing region of the second camera, the second field of view being different than the first field of view;

providing a processor electrically coupled to the projector, the first camera and the second camera;

emitting from the projector onto the surface, in a first instance, the first light having a first pattern selected from among the plurality of patterns;

acquiring in the first instance a first image of the surface with the first camera and sending a first digital signal to the processor in response;

determining a first set of three-dimensional coordinates of first points on the surface, the first set based at least in part on the first pattern, the first digital signal and the first distance;

carrying out a diagnostic procedure that determines a quality factor for the first set;

determining a second pattern of the first light selected from among the plurality of patterns, the second pattern based at least in part on results of the diagnostic procedure;

emitting from the projector onto the surface, in a second instance, the first light having the second pattern;

acquiring in the second instance a second image of the surface with the second camera and sending a second digital signal to the processor in response; and

determining a second set of three-dimensional coordinates of second points on the surface, the second set based at least in part on the second pattern, the second digital signal, and the second distance.

13. The method of claim 12 wherein the step of emitting in a second instance the first light from the projector includes a preceding step of moving the assembly from a first position to a second position.

14. The method of claim 13 wherein the step of moving the assembly includes directing the operator to move the assembly to the second position by activating indicator lights on the assembly.

15. The method of claim 13 wherein the step of moving the scanner includes projecting a light onto the object to indicate a direction of movement toward the second position.

16. The method of claim 13 wherein the step of moving the scanner includes indicating on a graphical representation on a display a portion of the object to be scanned.

17. The method of claim 12 wherein the step of carrying out the diagnostic procedure includes determining whether multipath interference is present.

18. The method of claim 17 wherein the step of carrying out the diagnostic procedure includes:

providing a computer-aided drawing (CAD) model of the object; and

verifying, based on the CAD model, the presence of the multipath interference by determining that rays of light from the projector are reflected from a first surface point of the object onto a second surface point of the object, wherein the second surface point is a point imaged by the first camera.

19. The method of claim 18 wherein in the step of emitting from the projector onto the surface, in a second instance, the first light, the first light having the second pattern is in a form of a line or a spot.

20. The method of claim 19 wherein in the step of emitting in the second instance a first light, the second pattern is in the form of a line that is swept in time or a spot that is swept in time.

21. The method of claim 17:

further including a step of obtaining three-dimensional coordinates of the surface of the object by scanning at least a portion of the surface; and

in the step of carrying out the diagnostic procedure, further including verifying, based on the obtained three-dimensional coordinates, the presence of the multipath interference by determining that rays of light from the projector are reflected from a first surface point of the object onto a second surface point of the object, wherein the second surface point is a point imaged by the first camera and determining the quality factor based at least in part on the presence of the multipath interference.

22. The method of claim 21 wherein in the step of emitting from the projector onto the surface, in a second instance, the first light having the second pattern, the second pattern is in a form of a line or a spot.

23. The method of claim 22 wherein, in the step of emitting from the projector onto the surface, in a second instance, the first light having the second pattern, the second pattern is in a form of a line that is swept in time or a spot that is swept in time.

24. The method of claim 12 wherein the step of carrying out a diagnostic procedure that determines a quality factor for the first set further includes:

determining a resolution of three-dimensional coordinates obtained from the first image; and

determining the quality factor based at least in part on the resolution.

25. The method of claim 12 wherein the second pattern is a temporally varying pattern.

26. The method of claim 17 wherein the step of determining whether multipath interference is present includes determining that multipath interference is present.