Computer vision system for position monitoring in three dimensions using non-coplanar light sources attached to a monitored object
First Claim
1. In an apparatus for monitoring the position and orientation of a rigid three-dimensional (3-D) object in space comprising:
- a single electronic camera having an image plane, a center of projection, an optical axis, and a camera reference coordinate frame being centered at the center of projection with x and y axes parallel to the image plane and a z-axis parallel to the optical axis,the single electronic camera producing an analog video signal;
a plurality of at least four light sources rigidly attached to the rigid 3-D object in a noncoplanar arrangement, these light sources projecting bright spots onto the image plane of the camera;
processing means for processing the analog video signal and determining a list of bright spot x-coordinates and y-coordinates in the camera reference coordinate frame;
computing means including memory means, output means and display means;
the computing means including pose computing means for approximately computing a translation vector and a rotation matrix of the rigid 3-D object in the camera reference coordinate frame;
the output means modifying images on the display means;
the improvement comprising;
the arrangement of light sources being any noncoplanar arrangement so long as the light sources are not all located along three orthogonal lines.
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Accused Products
Abstract
A sensing system for monitoring the position and orientation of a rigid object (20). At least 4 point light sources (24) are mounted on the surface of the object (20) in a noncoplanar arrangement. A single electronic camera (26) captures images (59) of the point light sources (24). Locations of the images (59) of the light sources (24) are detected in each video image, and a computer runs a task using these locations to obtain close approximations of the rotation matrix and translation vector (33) of the object (20) in a camera coordinate system (74) at video rate. The object is held by an operator (90) for three-dimensional cursor (94) control and interaction with virtual reality scenes (96) on computer displays (88), and for remote interactive control of teleoperated mechanisms.
562 Citations
15 Claims
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1. In an apparatus for monitoring the position and orientation of a rigid three-dimensional (3-D) object in space comprising:
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a single electronic camera having an image plane, a center of projection, an optical axis, and a camera reference coordinate frame being centered at the center of projection with x and y axes parallel to the image plane and a z-axis parallel to the optical axis, the single electronic camera producing an analog video signal; a plurality of at least four light sources rigidly attached to the rigid 3-D object in a noncoplanar arrangement, these light sources projecting bright spots onto the image plane of the camera; processing means for processing the analog video signal and determining a list of bright spot x-coordinates and y-coordinates in the camera reference coordinate frame; computing means including memory means, output means and display means; the computing means including pose computing means for approximately computing a translation vector and a rotation matrix of the rigid 3-D object in the camera reference coordinate frame; the output means modifying images on the display means;
the improvement comprising;the arrangement of light sources being any noncoplanar arrangement so long as the light sources are not all located along three orthogonal lines. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for three-dimensional (3-D) cursor control by an operator comprising:
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a single electronic camera having an image plane, a center of projection, an optical axis, and a camera reference coordinate frame being centered at the center of projection with x and y axes parallel to the image plane and a z-axis parallel to the optical axis, the single electronic camera producing an analog video signal; a plurality of at least four light sources configured in any noncoplanar arrangement so long as the light sources are not all located along three orthogonal lines, the light sources having a light source reference coordinate frame and light source coordinates in this object reference coordinate frame, these light sources projecting bright spots onto the image plane of the camera; means for processing the analog video signal and determining a list of bright spot locations in the camera reference coordinate frame; handle means for allowing an operator to hold and move the plurality of light sources freely in space; computing means for; repeatedly combining the bright spot locations with the light source coordinates; repeatedly producing a rotation matrix and a translation vector in the camera reference coordinate frame; repeatedly outputting onto display means in front of the operator'"'"'s eyes a perspective image of a 3-D virtual cursor located in space at a position and orientation defined by the rotation matrix and the translation vector.
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15. A sensing system for producing at successive time instants digital signals expressing positions and orientations of a rigid three-dimensional (3-D) object in space comprising:
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a single electronic camera having an image plane, a center of projection, an optical axis, and a camera reference coordinate frame being centered at the center of projection with x and y axes parallel to the image plane and a z-axis parallel to the optical axis, the single electronic camera producing an analog video signal; at least four noncoplanar light sources rigidly attached to the rigid 3D object in any noncoplanar arrangement so long as the light sources are not all located along three orthogonal lines, the light sources having light source coordinates in an object reference coordinate frame of the rigid 3D object, the light sources projecting bright spots onto the image plane of the camera; means for processing the analog video signal and determining a list of bright spot locations in the camera reference coordinate frame; computing means which include memory means and output means; the memory means storing a precomputed pseudo-inverse matrix depending only on the light source coordinates in the object reference coordinate frame; the computing means including pose computing means for; computing a translation vector and a rotation matrix of the rigid 3-D object in the camera reference coordinate frame, combining the precomputed pseudo-inverse matrix with the list of bright spot locations, by matrix multiplications, vector normalizations and vector cross-products, and providing to the output means for each frame of the video signal the three coordinates of the translation vector of the rigid 3-D object and the nine elements of the rotation matrix of the rigid 3-D object in digital form.
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Specification