Machine vision three dimensional profiling system

• US 5,193,120 A
• Filed: 02/27/1991
• Issued: 03/09/1993
• Est. Priority Date: 02/27/1991
• Status: Expired due to Fees

• Current Assignee: Mechanical Technology Incorporated
• Original Assignee: Mechanical Technology Incorporated
• Inventors: Tourtellott, John A., Gamache, Ronald W.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): KELLEY, CHRISTOPHER S
• Application Number:
  US07/661,679
• Time in Patent Office: 741 Days
• Field of Search: 382/1, 356/376, 356/3, 395/119, 340/729
• US Class Current: 382/286
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

A three dimensional imaging system having a diode laser and collimator along with a video camera and digital circuitry wherein when the light from the laser is collimated and hits the surface of an object with the reflected light images picked up by the video camera and the centroid location of each intersection is interpolated translating two dimensional pixels into three dimension coordinates.

Claims

1. A system for generating a three dimensional image of an object comprising

light projector means for generating lines of light onto an object;

imaging means, including an imaging lens, for viewing the lines of light at points along said lines at an angle to provide a profile of the object and providing an output corresponding to an image of the lines of light reflected from the object;

processing means for processing the output from the imaging means at points along the lines of light, said processing includes determining centroids for said points generating a two dimensional image point defined by the ordered pair (x, y) and transforming said image point to a three dimensional point; and

wherein said processing means utilizes optical magnification of said imaging lens and the geometry of the lines of light to process the image points in the following manner;

space="preserve" listing-type="equation">X=m*x+m*e*x.sup.3 +(dm/dz)*Z

space="preserve" listing-type="equation">Y=m*y+m*e*y.sup.3 +(dm/dz)*Z

where m is the optical magnification and e is the optical distortion and the equation for the geometry of lines in a geometric plane is

space="preserve" listing-type="equation">a*X+b*Y+c*Z=1

where a, b, and c are calibration parameters; and

wherein by solving these equations simultaneously image coordinates X, Y, Z are determined; and

means for generating said three dimensional image based on the coordinates determined by said processing means.

2. The system in accordance with claim 1 wherein said light projector means includes a laser and the image processing means includes a video camera and said laser is pulsed in synchronization with the video camera to remove blurring when the object is moving.

3. The system in accordance with claim 2 which includes optical filter to improve image contrast and measurement precision.

4. The system in accordance with claim 2, which includes feedback means coupled to the laser to provide amplitude modulation thereof based on variations in the objects reflectively.

5. The system in accordance with claim 1 wherein a numerical simplex method is used to determine calibration parameters to provide a minimum error in calculating Z values for the image coordinates.