THREE-DIMENSIONAL COORDINATE SCANNER AND METHOD OF OPERATION

• US 20130293684A1
• Filed: 07/01/2013
• Published: 11/07/2013
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Becker, Bernd-Dietmar, Bridges, Robert E.
• Granted Patent: US 9,482,529 B2
• Time in Patent Office: Days
• US Class Current: 348/47
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take 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 11/2518 Projection by scanning of the object
• CPC Class Codes: G01B 11/2545 with one projection direction and several detection directions, e.g. stereo
• CPC Class Codes: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4808 Evaluating distance, position or velocity data
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/491 Details of non-pulse systems

Abstract

A noncontact optical three-dimensional measuring device that includes a first projector, a first camera, a second projector, and a second camera; a processor electrically coupled to the first projector, the first camera, the second projector, 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 first projector, a first camera, a second projector and a second camera, wherein the first projector, the first camera, the second projector, and the second camera are in a fixed relation to one another, the first projector having a first light source, the first projector configured to emit onto a surface of an object a first light having at least one pattern, 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 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 projector having a second light source, the second projector configured to emit onto the surface of the object a second light, the second camera having a second lens and a second photosensitive array, the second camera configured to receive a second portion of the second light reflected off the surface and to produce a second 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 first projector, the second 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 signal to be collected at a first time and the second 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 signal, and determining three-dimensional coordinates of a second point on the surface based at least in part on the second signal.

2. The noncontact optical three-dimensional measuring device of claim 1 wherein the second light is a line of light along a direction perpendicular to a direction of propagation of the second light.

3. The noncontact optical three-dimensional measuring device of claim 1 wherein the at least one pattern includes at least three non-collinear pattern elements.

4. The noncontact optical three-dimensional measuring device of claim 3 wherein the second light includes a second pattern, the second pattern having at least three non-collinear pattern elements.

5. The noncontact optical three-dimensional measuring device of claim 2 wherein the line of light is a line pattern that is swept in time.

6. The noncontact optical three-dimensional measuring device of claim 2 wherein the line of light is a spot of light that is swept in time.

7. 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.

8. 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.

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

providing an assembly that includes a first projector, a first camera, a second projector and a second camera, wherein the first projector, the first camera, the second projector, and the second camera being in fixed in relation to one another, there being a first distance between the first projector and the first camera, there being a second distance between the second projector and the second camera, the first projector having a first light source, the first projector configured to emit onto the surface a first light having at least one pattern, 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 projector having a second light source, the second projector configured to emit onto the surface a second light, the second camera having a second lens and a second photosensitive array, the second camera configured to receive a second portion of the second 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 first projector, the first camera, the second projector, and the second camera;

emitting from the first projector onto the surface, in a first instance, the first light having the at least one pattern;

acquiring in the first instance a first image of the surface with the first camera and sending a first 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 at least one pattern, the first signal and the first distance;

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

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

acquiring in the second instance a second image of the surface with the second camera and sending a second 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 light, the second signal, and the second distance.

10. The method of claim 9 wherein the step of emitting in a second instance the second light from the second projector includes a preceding step of moving the assembly from a first position to a second position.

11. The method of claim 10 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.

12. The method of claim 10 wherein the step of moving the assembly includes projecting a light onto the object to indicate a direction of movement toward the second position.

13. The method of claim 11 wherein the step of moving the assembly includes indicating on a graphical representation on a display a portion of the object to be scanned.

14. The method of claim 9 wherein the step of carrying out a diagnostic procedure that determines a quality factor for the first set includes the quality factor based at least on part on that multipath interference is present.

15. The method of claim 14 wherein the step of carrying out a diagnostic procedure that determines a quality factor for the first set includes:

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

verifying, based on the CAD model, the presence of multipath interference by determining that rays of light from the first 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 multipath interference.

16. The method of claim 15 wherein in the step of emitting from the second projector onto the surface, in a second instance, the second light, the second light is in the form of a line or a spot.

17. The method of claim 16 wherein in the step of emitting in the second instance a second light, the second light is in the form of a line that is swept in time or a spot that is swept in time, the line of light being along a direction perpendicular to a direction of propagation of the second light.

18. The method of claim 14:

further including a step of obtaining a plurality of 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 plurality of three-dimensional coordinates, the presence of multipath interference by determining that rays of light from the first 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.

19. The method of claim 18 wherein in the step of emitting from the second projector onto the surface, in a second instance the second light, the second light is in the form of a line or a spot, the line being along a direction perpendicular to a direction of propagation of the second light.

20. The method of claim 19 wherein, in the step of emitting from the second projector onto the surface, in the second instance, the second light, the line or the spot is swept in time.

21. The method of claim 9 wherein, in the step of determining a quality factor for the first set further includes:

determining a resolution of the first set of three-dimensional coordinates; and

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

22. The method of claim 9 wherein the at least one pattern is a temporally varying pattern.