Three-dimensional coordinate scanner and method of operation

• US 10,119,805 B2
• Filed: 09/13/2016
• Issued: 11/06/2018
• 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.
• Primary Examiner(s): Aghevli, Reza
• Application Number:
  US15/263,877
• Publication Number:
  US 20160377410A1
• Time in Patent Office: 784 Days
• Field of Search: None
• 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, the first projector having a first light source operable to emit onto a surface of an object a first light having at least one pattern, the second projector having a second light source operable to emit onto the surface of the object a second light;

one or more processors for executing nontransitory computer readable instructions stored on a computer readable media, the one or more processors being operably coupled to the first projector, the first light source, the second projector, the second light source, and the computer readable media, the nontransitory computer readable instructions comprising;

acquiring with the first camera a first image of a first portion of the first light, the first portion of the first light being reflected by the surface;

determining three-dimensional coordinates of a first point on the surface based at least in part on the first image;

determining the presence of a multipath interference based at least in part on the first image;

causing the assembly to move from a first position to a second position in response to determining the presence of multipath interference;

acquiring with the second camera a second image of a second portion of the second light in response to moving the assembly from the first position to the second position; and

determining three-dimensional coordinates of a second point on the surface based at least in part on the second image.

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 camera has a first field of view and the second camera has a second field of view, the first field of view being 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 camera includes a first photosensitive array having a first pixel, the first pixel operable to capture light reflected off a first area of the surface, the second camera includes a second photosensitive array having a second pixel, the second pixel operable 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, the first projector having a first light source operable to emit onto a surface of an object a first light having at least one pattern, the second projector having a second light source, the second projector operable to emit onto the surface of the object a second light;

acquiring with the first camera a first image of a first area of the surface;

determining with one or more processors three-dimensional coordinates of a first point on the surface based at least in part on the first image;

determining with the one or more processors the presence of a multipath interference based at least in part on the first image;

moving the assembly from a first position to a second position in response to determining the presence of multipath interference;

acquiring with the second camera a second image of a second area of the surface in response to moving the assembly from the first position to the second position; and

determining with the one or more processors three-dimensional coordinates of a second point on the surface based at least in part on the second image.

10. The method of claim 9 wherein a portion of the first area overlaps a portion of the second area.

11. The method of claim 10 wherein the step of moving the assembly includes directing an 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 third light onto the object to indicate a direction of the 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 of a portion of the object to be scanned.

14. The method of claim 10 further comprising:

providing a computer-aided drawing (CAD) model of the object being measured prior to emitting the first light;

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 third point of the object onto a fourth point of the object, wherein the fourth point is a point imaged by the first camera; and

wherein determining the second position based at least in part on the presence of multipath interference as determined from the CAD model.

15. The method of claim 14 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.

16. The method of claim 15 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.

17. The method of claim 10 further comprising:

obtaining a plurality of three-dimensional coordinates of the surface of the object by scanning at least a portion of the surface;

verifying, based at least in part 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 third point of the object onto a fourth point of the object, wherein the fourth point is a point imaged by the first camera; and

determining the second position based at least in part on the presence of the multipath interference.

18. The method of claim 17 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.

19. The method of claim 18 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.

20. The method of claim 9 further including determining a resolution of the first set of three-dimensional coordinates.