Methods and systems of calculating the height of an object observed by a camera

• US 7,327,442 B1
• Filed: 11/29/2005
• Issued: 02/05/2008
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Fear, Andrew C., Herz, William Samuel
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US11/290,182
• Time in Patent Office: 798 Days
• Field of Search: 356/4.08
• US Class Current: 356/4.08
• CPC Class Codes: G01C 3/32 by focusing the object, e.g. on a ground glass screen
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves

Abstract

Methods and systems for automatically determining the height of an object observed by a camera are described. One such method involves determining the distance from the top of the object to the camera, determining the distance from the bottom of the object to the camera, measuring the angle of incidence, from the camera'"'"'s perspective, between the top and bottom of the object, and computing the height of the object from the two distances and the angle of incidence. The method may be computer controlled.

Claims

1. A method of calculating the height of an object observed by a camera, said method comprising:

determining a first distance from the top of said object to said camera, wherein said determining said first distance is performed with reference to a first known focal length;

determining a second distance from the bottom of said object to said camera, wherein said determining said second distance is performed with reference to a second known focal length;

measuring an angle of incidence, from said camera'"'"'s perspective, between the top and the bottom of said object; and

computing the height of said object from said first distance, said second distance, and said angle of incidence.

2. The method of claim 1, further comprising:

measuring an offset angle, wherein said offset angle is the angle between a horizontal plane and the top of said object; and

determining a vertical offset distance from said first distance and said offset angle.

3. The method of claim 1, wherein said measuring an angle of incidence is accomplished by referencing a leveling device incorporated into said camera.

4. The method of claim 1, wherein said measuring an angle of incidence is accomplished by referencing known distances between a plurality of autofocus sensors incorporated into said camera.

5. The method of claim 1, wherein said camera comprises a video camera.

6. The method of claim 5, further comprising:

repeatedly calculating the height of said object observed by said video camera; and

computing an average height of said object.

7. A system for calculating the height of an object observed by a camera, said system comprising:

a camera; and

a processor, coupled to said camera,

wherein said camera is configured to autofocus on the top and bottom of said object;

wherein said processor is configured to compute a first distance from the top of said object to said camera, a second distance from the bottom of said object to said camera, and an angle of incidence, from said camera'"'"'s perspective, between the top and the bottom of said object; and

wherein said processor is further configured to calculate the height of said object from said first distance, said second distance, and said angle of incidence.

8. The system of claim 7, wherein said camera comprises an array of auto-focus elements, and wherein said processor is configured to determine said angle of incidence by computing an angle between two of said array of auto-focus elements.

9. The system of claim 8, wherein said array of auto-focus elements provides continuous coverage across a field of view of said camera.

10. The system of claim 9, wherein said array of auto-focus elements allows said camera to autofocus on the top and bottom of said object without changing the position of said camera.

11. The system of claim 7, wherein said camera comprises a video camera.

12. The system of claim 7, wherein said camera comprises a still picture camera.

13. The system of claim 7, wherein said camera comprises a level meter and a pivot mount, and wherein said processor is configured to determine said angle of incidence by referencing said level meter.

14. The system of claim 7, wherein said processor is further configured to calculate a vertical offset distance of said object, said vertical offset being the distance between the top of said object and a horizontal plane defined by said camera.

15. A computer implemented compression/decompression process for video data, comprising:

storing compressed video images of an object, said object having been observed by a camera system;

storing focal distance information, said focal distance information comprising distance information between said camera system and a plurality of points on said object; and

storing angle of incidence information, said angle of incidence information describing the angle between two of said plurality of points on said object, from said camera'"'"'s perspective.

16. The compression/decompression process of claim 15, further comprising:

storing compressed audio data.

17. The compression/decompression process of claim 15, further comprising:

calculating a distance between two of said plurality of points on said object by using said stored focal distance information and said store angle of incidence.

18. The compression/decompression process of claim 17, wherein said distance between two of said plurality of points on said object corresponds to the height of said object.

19. The compression/decompression process of claim 17, wherein said distance between two of said plurality of points on said object corresponds to the width of said object.

20. The compression/decompression process of claim 15, further comprising:

storing offset angle information, said offset angle information describing the angle between a horizontal plane and one of said plurality of points on said object, from said camera'"'"'s perspective.