Registration of three-dimensional coordinates measured on interior and exterior portions of an object

Patent metadata

Field	Value
Publication number	US-2017191822-A1
Application number	US-201615358218-A
Country	US
Kind code	A1
Filing date	Nov 22, 2016
Priority date	Dec 30, 2015
Publication date	Jul 6, 2017
Grant date	—

Abstract

A dimensional measuring device includes an overview camera and a triangulation scanner. A six-DOF tracking device tracks the dimensional measuring device as the triangulation scanner measures three-dimensional (3D) coordinates on an exterior of the object. Cardinal points identified by the overview camera are used to register in a common frame of reference 3D coordinates measured by the triangulation scanner on the interior and exterior of the object.

First claim

1 . A method for measuring three-dimensional (3D) coordinates comprising:
providing a dimensional measuring device that includes a body and a triangulation scanner coupled to the body, the triangulation scanner having a projector and a camera, the dimensional measuring device having a device frame of reference; in a first instance:
determining with a six degree-of-freedom (six-DOF) tracking system a first position and a first orientation of the dimensional measuring device, the six-DOF tracking system being separate from the dimensional measuring device, the six-DOF tracking system having a system frame of reference;
projecting with the projector a first pattern of light onto a first portion of an object and capturing with the camera a first triangulation image of the projected first pattern of light on the object;
determining in the device frame of reference first 3D coordinates of a first 3D-coordinates point on the object based at least in part on the projected first pattern of light and the first triangulation image;
in a second instance:
determining with the six-DOF tracking system a second position and a second orientation of the dimensional measuring device;
capturing with the camera a second overview image of a second portion of the object and in response determining second 2D coordinates of a first cardinal point in the second overview image;
projecting with the projector a second pattern of light onto the second portion of the object and capturing with the camera a second triangulation image of the projected second pattern of light on the object;
determining in the device frame of reference second 3D coordinates of a second 3D-coordinates point on the object based at least in part on the projected second pattern of light and the second triangulation image;
in a third instance:
positioning the dimensional measuring device so as to be inaccessible to measurement by the six-DOF tracking system;
capturing with the camera a third overview image of a third portion of the object and in response determining third 2D coordinates of the first cardinal point in the third overview image and third 2D coordinates of a second cardinal point in the third overview image;
projecting with the projector a third pattern of light onto the third portion of the object and capturing with the camera a third triangulation image of the projected third pattern of light on the object;
determining in the device frame of reference third 3D coordinates of a third 3D-coordinates point on the object based at least in part on the projected third pattern of light and the third triangulation image;
determining in the system frame of reference first system 3D coordinates of the first 3D-coordinates point, second system 3D coordinates of the second 3D-coordinates point and third system 3D coordinates of the third 3D-coordinates point, the determining based at least in part on the first position and the first orientation of the dimensional measuring device in the system frame of reference, the second position and the second orientation of the dimensional measuring device in the system frame of reference, the first 3D coordinates in the device frame of reference, the second 3D coordinates in the device frame of reference, the third 3D coordinates in the device frame of reference, the second 2D coordinates of the first cardinal point, the third 2D coordinates of the first cardinal point, and the third 2D coordinates of the second cardinal point; and storing the first system 3D coordinates of the first 3D-coordinates point, the second system 3D coordinates of the second 3D-coordinates point, and the third systems 3D coordinates of the third 3D-coordinates point.

2 . The method of claim 1 wherein, in determining with a six-DOF tracking system a first position and a first orientation, the six-DOF tracking system includes a six-DOF laser tracker.

3 . The method of claim 2 wherein, in providing a dimensional measuring device that includes a body and a triangulation scanner, the triangulation scanner further includes a six-DOF target configured for measurement by the six-DOF laser tracker.

4 . The method of claim 1 wherein, in determining with a six-DOF tracking system a first position and a first orientation, the six-DOF tracking system includes a camera bar having a plurality of camera-bar cameras.

5 . The method of claim 4 wherein, in providing a dimensional measuring device that includes a body and a triangulation scanner, the triangulation scanner further includes a collection of marks visible to the plurality of camera-bar cameras.

6 . The method of claim 5 wherein, in providing a dimensional measuring device that includes a body and a triangulation scanner, a first mark in the collection of marks is selected from the group consisting of: a light source and a reflective spot.

7 . The method of claim 1 wherein, in determining with a six-DOF tracking system a first position and a first orientation, the six-DOF tracking system includes a plurality of rotating cameras, each rotating camera in the plurality of rotating cameras having an angular transducer configured to measure an angle of rotation.

8 . The method of claim 7 wherein, in providing a dimensional measuring device that includes a body and a triangulation scanner, the triangulation scanner further includes a collection of marks visible to the plurality of rotating cameras.

9 . The method of claim 5 wherein, in determining with a six-DOF tracking system a first position and a first orientation, the camera bar is coupled to a plurality of retroreflector targets fixed in a camera-bar frame of reference of the camera bar, the laser tracker configured to measure 3D coordinates of the plurality of retroreflector targets.

10 . The method of claim 1 wherein, in the second instance, the first cardinal point is selected from the group consisting of: a natural feature, an artificial mark, and a projected spot of light.

11 . The method of claim 10 wherein, in the third instance, the second cardinal point is selected from the group consisting of: a natural feature, an artificial mark, and a projected spot of light.

12 . The method of claim 11 wherein, in the second instance and the third instance, the first cardinal point and the second cardinal point are interest points.

13 . The method of claim 12 wherein, in the second instance and the third instance, the interest points are determined based on a method selected from the group consisting of: edge detection, blob detection, ridge detection, corner detection, and scale invariant feature transform (SIFT) detection.

14 . The method of claim 1 wherein, in providing a dimensional measuring device that includes a body and a triangulation scanner, the triangulation scanner further includes a tactile probe having a probe tip.

15 . The method of claim 14 further including determining 3D coordinates of the probe tip touched to a surface of the object, the determining further based on a position of the probe tip in the device frame of reference.

16 . The method of claim 1 further comprising:
in a fourth instance:
positioning the triangulation scanner so as to be inaccessible to measurement by the six-DOF tracking system;
capturing with the camera a fourth overview image of a fourth portion of the object and in response determining fourth 2D coordinates of a fourth cardinal point in the fourth overview image and fourth 2D coordinates of a fifth cardinal point in the fourth overview image;
projecting with the projector a fourth pattern of light onto the fourth portion of the object and capturing with t

Assignees

• Faro Tech Inc

Inventors

• Becker Bernd-Dietmar
• Bridges Robert E
• Stiebeiner Ariane
• Heidemann Rolf
• Wolke Matthias

Classifications

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S17/66

  Tracking systems using electromagnetic waves other than radio waves · CPC title

• G01S17/89

  for mapping or imaging · CPC title

• G06T2207/10004

  Still image; Photographic image · CPC title

• G01B21/042

  Calibration or calibration artifacts (G01B3/30, G01B9/02072 take precedence) · CPC title