LINE SCANNER THAT USES A COLOR IMAGE SENSOR TO IMPROVE DYNAMIC RANGE

• US 20150185000A1
• Filed: 12/23/2014
• Published: 07/02/2015
• Est. Priority Date: 12/31/2013
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Wilson, Christopher Michael, Atwell, Paul C.
• Granted Patent: US 9,658,061 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• 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: G01B 2210/52 Combining or merging partially overlapping images to an overall image
• CPC Class Codes: G06N 3/084 Backpropagation, e.g. using gradient descent

Abstract

A method for measuring 3D coordinates of points on a surface of an object by providing an articulated arm connected to a laser line probe. The laser line probe having a color camera sends color images to a processor, which determines 3D surface coordinates using triangulation. The processor weights each of the colors received from the pixels to enable dark and bright regions of the surface to be measured simultaneously.

Claims

1. A method for measuring three-dimensional (3D) coordinates of points on a surface of an object, the method comprising:

providing a 3D coordinate measurement device, the device including a manually positionable articulated arm portion having opposed first and second ends, the second end coupled to a base, the arm portion including a plurality of connected arm segments, a laser line probe, and an electrical circuit, each of the arm segments including at least one position transducer configured to produce a position signal, the laser line probe coupled to the first end, the laser line probe including a projector and a camera, the projector separated from the camera by a baseline, the baseline being a line segment, the projector configured to project a line of light onto the surface, the camera including a lens and photosensitive array, the camera configured to form an image on the photosensitive array of the line of light projected onto the object, the photosensitive array having a plurality of pixels, each pixel configured to provide electrical signal levels for a plurality of colors, the camera configured to send the electrical signal levels from the pixels to the electrical circuit, the electrical circuit including a processor;

projecting the line of light onto the surface;

forming a color image of the line of light on the photosensitive array;

sending to the electrical circuit an electrical signal in response to the color image, the electrical signal containing a signal level for each of the plurality of colors for each of the plurality of pixels;

determining with the processor an effective illumination level for each pixel, the effective illumination level for each pixel based at least in part on the signal level for that pixel for each of the plurality of colors; and

determining with the processor the 3D coordinates of points on the surface, the 3D coordinates based at least in part on a length of the baseline, an orientation of the projector to the baseline, an orientation of the camera to the baseline, the effective illumination level for each pixel, and the position signals.

2. A laser line probe, comprising;

a projector, a camera, and an electrical circuit, the projector separated from the camera by a baseline, the baseline being a line segment, the projector configured to project a line of light onto a surface, the camera including a lens and photosensitive array, the camera configured to form an image on the photosensitive array of the line of light projected onto the object, the photosensitive array having a plurality of pixels, each pixel configured to provide electrical signal levels for a plurality of colors, the camera configured to send the electrical signal levels from the pixels to the electrical circuit, the electrical circuit including a processor, the processor configured to determine an effective illumination level for each pixel, the effective illumination level for each pixel based at least in part on the signal level for that pixel for each of the plurality of colors, and determine 3D coordinates of points on the surface, the 3D coordinates based at least in part on a length of the baseline, an orientation of the projector to the baseline, an orientation of the camera to the baseline, and the effective illumination level for each pixel.

3. The laser line probe of claim 2, further comprising a handle enclosing electronic components.

4. The laser line probe of claim 2, further comprising a probe tip.

5. The laser line probe of claim 2, wherein the photosensitive array is a color CCD.

6. The laser line probe of claim 2, further comprising a mechanical coupler configured to attach the laser line probe to a host device.

7. The laser line probe of claim 6, wherein the host device is an articulated arm coordinate measurement machine.