THREE-DIMENSIONAL MEASURING APPARATUS, THREE-DIMENSIONAL MEASURING METHOD, AND THREE-DIMENSIONAL MEASURING PROGRAM

• US 20150049345A1
• Filed: 03/22/2013
• Published: 02/19/2015
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Miyagawa, Hiroshi
• Granted Patent: US 9,239,235 B2
• Time in Patent Office: Days
• US Class Current: 356/625
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/005 coordinate measuring machines
• CPC Class Codes: G01B 11/2522 the position of the object changing and being recorded
• CPC Class Codes: G01B 11/2545 with one projection direction and several detection directions, e.g. stereo

Abstract

A three-dimensional measuring apparatus 1 projects slit light from a projector 7 onto a work 2 and a stereo camera 5 captures an image of the work projected by the slit light. A control apparatus 10 of the three-dimensional measuring apparatus 1 temporarily identifies a correspondence between a bright line 4j on a first image of the captured stereo image and a light-section plane 6Pj and projects the bright line 4j onto the light-section plane 6Pj. The bright line projected onto the light-section plane 6Pj is projected onto a second image. The control apparatus 10 calculates the level of similarity between a bright line 4jX projected onto the second image and a bright line on the second image and determines a result of identified correspondence relationship between the bright line 4jX and the bright line on the second image.

Claims

1. A three-dimensional measuring apparatus comprising:

a projector configured to project slit light onto a work;

a first camera configured to capture an image of the work projected by the slit light;

a second camera configured to capture an image of the work projected by the slit light from a position different from that of the first camera; and

a control apparatus configured to store a three-dimensional plane equation of a light-section plane of the slit light, identify a correspondence among a bright line generated on a first image captured by the first camera by projecting the slit light, a bright line generated on a second image captured by the second camera by projecting the slit light, and the three-dimensional plane equation of the light-section plane, and perform three-dimensional measuring of the work by a principle of triangulation by using a correspondence relationship among any of the bright line on the first image, the bright line on the second image, and the light-section plane.

2. The three-dimensional measuring apparatus according to claim 1, wherein

the control apparatus temporarily identifies a correspondence between the bright line on the first image and the light-section plane, temporarily projects the bright line on the first image onto the light-section plane in a three-dimensional virtual space, and thereafter projects the bright line onto the second image captured by the second camera through the light-section plane, and identifies a correspondence among the light-section plane and the bright lines on the images of the first and the second cameras on the basis of a level of similarity between the bright line on the first image which is projected onto the second image and the bright line on the second image.

3. The three-dimensional measuring apparatus according to claim 1, wherein

the projector projects a plurality of slit lights onto the work, and

the control apparatus temporarily identifies a correspondence between only the light-section planes that pass through a range, in which a predetermined three-dimensional range in which the work is located and a three-dimensional range corresponding to a range in which the bright line is present on the first image overlap each other, among a plurality of the light-section planes, and the bright line on the first image, and calculates the level of similarity.

4. The three-dimensional measuring apparatus according to claim 1, wherein

if a three-dimensional position of the bright line when the bright line on the first image is projected onto one of the light-section planes whose correspondence is temporarily identified in a three-dimensional virtual space is out of a predetermined three-dimensional range in which the work is located, the control apparatus changes the light-section plane whose correspondence is to be identified without calculating the level of similarity.

5. A three-dimensional measuring method in which slit lights are projected from a projector onto a work and three-dimensional measuring of the work is performed by using a captured image of the work projected by the slit lights and three-dimensional plane equations of light-section planes of the plurality of slit lights, the method comprising:

an image acquisition step in which an arithmetic unit acquires a first image and a second image of the work projected by the plurality of slit lights, which are captured from different positions;

a step of identifying a set of corresponding bright lines in which the arithmetic unit determines an identification of a correspondence among each bright line on the first and the second images and the three-dimensional plane equations of the light-section planes; and

a measuring step in which the arithmetic unit performs three-dimensional measuring of the work by a principle of triangulation by using a correspondence relationship between any of the bright line on the first image, the bright line on the second image, and the light-section planes.

6. The three-dimensional measuring method according to claim 5, wherein

the step of identifying a set of corresponding bright lines temporarily identifies a correspondence between each bright line on the first image and one of the light-section planes of the plurality of slit lights, temporarily projects the bright line on the first image onto the corresponding light-section plane in a three-dimensional virtual space, and thereafter projects the bright line onto the second image through the light-section plane, and determines whether or not the light-section plane and the bright lines on the first and the second images appropriately correspond to each other on the basis of a level of similarity between the bright line on the first image which is projected onto the second image and the bright line on the second image.

7. A three-dimensional measuring program causing a computer to execute the steps of the three-dimensional measuring method according to claim 5.