SYSTEM AND METHOD FOR DIMENSIONING OBJECTS USING STEREOSCOPIC IMAGING

• US 20100290665A1
• Filed: 05/13/2009
• Published: 11/18/2010
• Est. Priority Date: 05/13/2009
• Status: Active Grant

• Current Assignee: Applied Vision Corporation (Antares Vision S.p.A.)
• Original Assignee: Applied Vision Company, LLC
• Inventors: Brumbaugh, Kris, Kress, Michael Leo, Sones, Richard A.
• Granted Patent: US 8,284,988 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G01B 11/024 by means of diode-array scanning
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/20224 Image subtraction
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 7/62 of area, perimeter, diameter or volume
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19
• CPC Class Codes: G06V 20/64 Three-dimensional objects

Abstract

A method and configuration to estimate the dimensions of a cuboid. The configuration includes two image acquisition units offset from each other with at least one of the units positioned at a defined acquisition height above a background surface. Image processing techniques are used to extract a perimeter of a top surface of the cuboid, placed on the background surface, from pairs of acquired images. A height estimation technique is used to calculate an absolute height of the cuboid. The absolute height of the cuboid is used, along with the extracted perimeter of the top surface of the cuboid, to calculate an absolute length and an absolute width of the cuboid. The height, length, and width may be used to calculate an estimated volume of the cuboid.

Claims

1. A method to estimate the dimensions of a cuboid structure, said method comprising:

acquiring a primary background image of a background surface, whereby said acquiring of said primary background image is accomplished from a primary acquisition position which is at a defined image acquisition height above said background surface;

acquiring a secondary background image of said background surface, whereby said acquiring of said secondary background image is accomplished from a secondary acquisition position which is offset from said primary acquisition position by a defined offset distance;

positioning a cuboid structure onto said background surface such that a top surface of said cuboid structure is substantially parallel to said background surface;

acquiring a primary cuboid image of said cuboid structure on said background surface, whereby said acquiring of said primary cuboid image is accomplished from said primary acquisition position;

acquiring a secondary cuboid image of said cuboid structure on said background surface, whereby said acquiring of said secondary cuboid image is accomplished from said secondary acquisition position;

subtracting said primary background image from said primary cuboid image to form a primary subtraction image;

subtracting said secondary background image from said secondary cuboid image to form a secondary subtraction image;

spatially correlating at least one common feature of said primary subtraction image and said secondary subtraction image;

estimating dimensions of said cuboid structure.

2. The method of claim 1 further comprising correcting said primary background image, said secondary background image, said primary cuboid image, and said secondary cuboid image for optical distortion before forming said subtraction images.

3. The method of claim 1 further comprising performing edge enhancement and edge extraction on said primary background image, said secondary background image, said primary cuboid image, and said secondary cuboid image before forming said subtraction images.

4. The method of claim 3 further comprising dilating said edge enhanced and edge extracted primary background image and dilating said edge enhanced and edge extracted secondary background image before forming said subtraction images.

5. The method of claim 1 further comprising finding a best-fit rectangle within each of said primary subtraction image and said secondary subtraction image to define a primary rectangle and a secondary rectangle each representing said top surface of said cuboid structure before performing said spatial correlating.

6. The method of claim 1 wherein said estimating dimensions of said cuboid structure includes:

calculating a spatial image shift between said primary subtraction image and said secondary subtraction image using said common correlated feature;

calculating an absolute height of said cuboid structure by applying a height estimation technique using at least said calculated spatial image shift and said image acquisition height; and

calculating an absolute length and an absolute width of said cuboid structure using said calculated absolute height and a best-fit rectangle extracted from at least one of said primary subtraction image and said secondary subtraction image.

7. The method of claim 6 further comprising calculating an estimated volume of said cuboid structure using said absolute length, said absolute width, and said absolute height.

8. The method of claim 1 wherein said background surface comprises a top surface of a scale capable of measuring a weight of said cuboid structure.

9. The method of claim 1 wherein said cuboid structure comprises a package to be shipped.

10. The method of claim 1 further comprising measuring a weight of said cuboid structure.

11. The method of claim 10 further comprising assigning a cost of shipping to said cuboid structure based on said estimated dimensions and said measured weight.

12. An image acquisition and processing configuration to estimate the dimensions of a package, said configuration comprising:

a primary image acquisition unit positioned at a primary acquisition location;

a secondary image acquisition unit positioned at a secondary acquisition location which is offset from said primary acquisition location by a defined offset distance;

a platform having a substantially horizontal top surface positioned substantially directly beneath said primary image acquisition unit such that said primary image acquisition unit is at a defined image acquisition height above said top surface of said platform; and

a vision engine operatively connected to said image acquisition units and capable of;

triggering said image acquisition units to acquire background images of said top surface of said platform and package images of a top surface of a package placed on said top surface of said platform,

receiving said acquired images from said image acquisition units;

storing said received images, and

processing said received images to estimate length, width, and height dimensions of said package.

13. The configuration of claim 12 wherein said platform comprises a scale capable of weighing said package placed on said top surface of said platform.

14. The configuration of claim 12 further comprising a scale having said platform resting thereon and capable of weighing said package placed on said top surface of said platform.

15. The configuration of claim 12 wherein each of said image acquisition units comprises a camera.

16. The configuration of claim 12 further comprising at least one illuminator positioned to illuminate said top surface of said platform and said top surface of said package placed on said platform, wherein said at least one illuminator is operatively connected to said vision engine and is capable of being turned on by said vision engine.

17. The configuration of claim 16 wherein said at least one illuminator and said image acquisition units operate in an infrared range of wavelengths.

18. The configuration of claim 16 wherein said at least one illuminator and said image acquisition units operate in an ultraviolet range of wavelengths.

19. The configuration of claim 16 wherein said at least one illuminator and said image acquisition units operate in a visible range of wavelengths.

20. The configuration of claim 12 wherein said configuration is capable of accommodating cuboid-shaped packages ranging in dimensions between 2 inches by 2 inches by one inch and 36 inches by 24 inches by 26 inches.

21. The configuration of claim 12 wherein said processing performed by said vision engine includes:

correcting each of said acquired images for optical distortion to form a corrected primary background image, a corrected secondary background image, a corrected primary package image, and a corrected secondary package image;

performing edge enhancement and edge extraction on each of said corrected images to form a primary background edge image, a secondary background edge image, a primary package edge image, and a secondary package edge image;

subtracting said primary background edge image from said primary package edge image to form a primary subtraction image;

subtracting said secondary background edge image from said secondary package edge image to form a secondary subtraction image;

finding a best-fit rectangle within said primary subtraction image to extract a primary rectangle representing said top surface of said package;

finding a best-fit rectangle within said secondary subtraction image to extract a secondary rectangle representing said top surface of said package;

spatially correlating at least one common feature of said primary rectangle and said secondary rectangle;

calculating a spatial image shift between said primary rectangle and said secondary rectangle using said common correlated feature;

calculating an absolute height of said package by applying a height estimation technique using at least said calculated spatial image shift and said image acquisition height; and

calculating an absolute length and an absolute width of said package using said calculated absolute height of said package and at least one of said primary rectangle and said secondary rectangle.

22. The configuration of claim 21 further comprising calculating an estimated volume of said package using said absolute length, said absolute width, and said absolute height.

23. The configuration of claim 21 wherein said processing performed by said vision engine further includes binarizing said primary subtraction image and said secondary subtraction image before finding said best-fit rectangles.

24. The configuration of claim 12 further comprising an optical bandpass filter operatively connected to said primary image acquisition unit to reject ambient light.

25. The configuration of claim 12 further comprising an optical bandpass filter operatively connected to said secondary image acquisition unit to reject ambient light.

26. The configuration of claim 16 further comprising a linear polarizer operatively connected to said at least one illuminator.

27. The configuration of claim 26 further comprising a cross-polarizer operatively connected to said primary image acquisition unit.

28. The configuration of claim 26 further comprising a cross-polarizer operatively connected to said secondary image acquisition unit.