Optical methods for remotely measuring objects

• US 20040008259A1
• Filed: 04/10/2003
• Published: 01/15/2004
• Est. Priority Date: 04/10/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Canesta Incorporated (Microsoft Corporation)
• Inventors: Gokturk, Salih Burak, Surucu, Fahri, Tomasi, Carlo
• Granted Patent: US 7,310,431 B2
• Time in Patent Office: Days
• US Class Current: 348/207.1
• CPC Class Codes: G01B 11/2509 Color coding
• CPC Class Codes: G01B 11/2545 with one projection direction and several detection directions, e.g. stereo
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

A class of measurement devices can be made available using a family of projection patterns and image processing and computer vision algorithms. The proposed system involves a camera system, one or more structured light source, or a special pattern that is already drawn on the object under measurement. The camera system uses computer vision and image processing techniques to measure the real length of the projected pattern. The method can be extended to measure the volumes of boxes, or angles on planar surfaces.

Claims

1. A method for remotely measuring the geometrical attributes of an object of known shape, the method comprising the steps of:

illuminating the object with an optical pattern of known shape using a light source of known wavelength; and

optically obtaining an image to observe the reflected pattern on said object from said light source, using a camera whose location and orientation is known with respect to the light source; and

executing a computer-implemented process to locate a plurality of key points in the image obtained by the camera; and

executing another computer-implemented process to obtain a plurality of geometrical attributes of said object using the plurality of key points.

2. The method of claim 1, wherein the of the step of executing another computer-implemented process to obtain a plurality of geometrical attributes of said object includes obtaining the geometrical attributes corresponding to one or more of a box, a cube, a rectangular parallelepiped, a circle, a sphere or cylindroid.

3. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining a straight-line distance of two points identified as being on the image of the object.

4. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining a surface-line distance of two points on the object.

5. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining an angle of two lines on the object.

6. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining a center of a line on the object.

7. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining a mid-point of a line on the object.

8. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining a center of the object.

9. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining one or more of a width, a length and a depth of an object the object.

10. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining a perimeter of the object.

11. The method of claim 1, wherein the step of executing another computer-implemented process to obtain a plurality of geometrical attributes includes determining one or more of a surface area, volume, and weight of the object.

12. The method of claim 1, wherein is the step of illuminating the object includes illuminating one of:

a) a straight line,

b) a straight line with tick marks,

c) plurality of lines in parallel or crossing each other,

d) a grid or plurality of known shapes.

13. The method of claim 1, further including the step of enhancing the image of the reflected light pattern captured by said camera to more accurately locate the key points.

14. The method of claim 1, wherein the step of executing a computer-implemented process includes executing instructions for performing a Hough Transformation.

15. The method of claim 1, wherein the step of executing another computer-implemented process includes executing instructions for performing a triangulation in order to obtain a three dimensional coordinate of one or more of the plurality of key points.

16. The method of claim 1, wherein the step of executing a computer-implemented process includes performing an edge following process to find the locations of key points in the image.

17. The method of claim 1, wherein said object is a rectangular parallelepiped, and the optical pattern intersects one face of the rectangular parallelepiped on at least five points and intersects an orthogonal face to said face on at least an additional point.

18. The method of claim 1, wherein said object is a rectangular parallelepiped, and the said optical pattern is a pair of lines. 19.

19. The method of claim 1, wherein said object is a rectangular, and the said optical pattern intersects the rectangle on at least five points.

20. A system for remotely measuring the geometrical attributes of an object of known shape, the system comprising:

a processor;

a memory storing at least one software module;

a first optical system projecting an optical pattern of a known shape and wavelength;

a second optical system in a known position relative the first optical system having a field of view encompassing at least the reflected pattern from the said object;

wherein the at least one software module is executable by the processor to locate a plurality of key points in the image obtained by the second optical system, and to calculate the three dimensional world-coordinates of said points.

21. The system of claim 20, wherein the at least one software module is executable by the processor to locate the plurality of key points in the image using a Hough Transformation process.

22. The system in claim 20, wherein the at least one software module is executable by the processor to determine geometric measurements using the plurality of key points.

23. The system in claim 20, wherein the at least one software module is executable by the processor to transfer the image to a companion device and to use the processing power of the companion device to execute the instructions of the module.

24. The system in claim 20, where said second optical system includes a camera sensor that detects the reflected portion of said optical pattern.

25. The system in claim 20, where said second optical system is substantially sensitive to optical energy of said optical wavelength.

26. The system in claim 20, where the operation of the first and second optical systems are substantially synchronized.

27. A method for remotely measuring the geometrical attributes of an object of known shape, the method comprising the steps of:

a) drawing on said object a pattern of known shape; and

an additional pattern of known shape and size;

b) optically obtaining an image to observe the pattern on said object, using a camera; and

c) applying image processing to locate a plurality of key points in the image obtained by the said camera; and

d) applying geometrical processing to obtain a plurality of geometrical attributes of said object.