Angled axis machine vision system and method

• US 7,898,569 B2
• Filed: 02/15/2007
• Issued: 03/01/2011
• Est. Priority Date: 07/16/2004
• Status: Active Grant

• Current Assignee: Vision Robotics Corporation
• Original Assignee: Vision Robotics Corporation
• Inventors: Wallach, Bret, Koselka, Harvey
• Primary Examiner(s): Banks Harold; Marsha D
• Assistant Examiner(s): HALLENBECK-HUBER, JEREMIAH CHARLES
• Application Number:
  US11/675,263
• Publication Number:
  US 20070195160A1
• Time in Patent Office: 1,475 Days
• Field of Search: 348/42, 348 51- 60, 348/139, 382/154
• US Class Current: 348/139
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/85 Stereo camera calibration
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals

Abstract

Angled axis machine vision system having a camera system angled with respect to an axis of coordinate system of environment. Eliminates problem of utilizing horizontal, vertical lines in environment for distance calculations when horizontal and vertical lines are parallel or close to parallel to axis lying between camera centers of camera system. With camera centers angled about roll axis, horizontal and vertical lines in environment appear as angled lines in images taken from the cameras enabling more accurate distance calculations. With angled axis rotation it is still possible for lines in environment to be parallel to axis defined between camera centers, but instances are rare in real world environments. Camera mount may rotate wherein two sets of pictures are taken and two sets compared for the number of lines which are parallel to axis of camera centers wherein set of pictures with least lines parallel is used for distance calculations.

Claims

1. A system for calculating distances to objects within three-dimensional space in an environment comprising horizontal and vertical lines using an angled axis machine vision system comprising:

a first camera;

a second camera mounted coplanar to said first camera wherein said first camera and said second camera comprise collinear horizontal center lines;

a camera mount coupled with said first camera and said second camera wherein said camera mount is at a rotation of a first axial angle with between 0 and 90 degrees about a roll axis defined as parallel to ground; and

,

a computer configured to perform a distance calculation wherein said computer is coupled with said first camera and said second camera and configured to calculate a distance based on a first picture obtained from said first camera and a second picture obtained from said second camera to a feature found along an epipolar line parallel to said collinear horizontal center lines and wherein said first axial angle is selected to differ from horizontal and vertical lines at 0 and 90 degrees respectively in an environment to increase useable detail and minimize errors in said distance calculation.

2. The system of claim 1 wherein said first axial angle is substantially 45 degrees.

3. The system of claim 1 wherein said first axial angle is substantially 37 degrees.

4. The system of claim 1 wherein said first axial angle is substantially 29 degrees.

5. The system of claim 1 wherein said camera mount is rotated in a second axial angle between 0 and 90 degrees about a pitch axis defined as parallel to an axis that runs through said first camera and said second camera and orthogonal to said roll axis.

7. The method of claim 5 wherein said first axial angle is substantially 45 degrees.

8. The method of claim 5 wherein said first axial angle is substantially 37 degrees.

9. The method of claim 5 wherein said first axial angle is substantially 29 degrees.

10. The method of claim 5 further comprising:

rotating said camera mount in a second axial angle between 0 and 90 degrees about a pitch axis defined as parallel to an axis that runs through said first camera and said second camera and orthogonal to said roll axis.

6. A method for calculating distances to objects within three-dimensional space in an environment comprising horizontal and vertical lines using an angled axis machine vision system comprising:

attaching a first camera and a second camera to a camera mount wherein said first camera and said second camera comprise collinear horizontal center lines;

rotating said camera mount in a first axial angle to a rotation between 0 and 90 degrees about a roll axis defined as parallel to ground;

obtaining a first picture from said first camera;

obtaining a second picture from said second camera; and

,

calculating a distance using said first picture obtained from said first camera and said second picture obtained from said second camera to a feature found along an epipolar line parallel to said collinear horizontal center lines by selecting said first axial angle to differ from horizontal and vertical lines at 0 and 90 degrees respectively in an environment to increase useable detail and minimize errors in said distance calculation.