Method and system for the determination of object positions in a volume
First Claim
1. A system for determining position information about a first object in a volume, comprising:
- a global coordinate system defined in the volume;
a local coordinate system in a known fixed relationship to the first object;
a pattern of two or more stripes in a fixed relationship to the first object, wherein a first stripe of the pattern is characterized by a first reference line defined relative to the local coordinate system, and a second stripe of the pattern is characterized by a second reference line defined relative to the local coordinate system;
two or more cameras, wherein each camera can output a 2-dimensional video frame, and wherein each video frame has a known relationship to the global coordinate system;
a digital computer adapted to receive the video frame output from each camera; and
a memory connected to the computer and containing a program of instructions which cause the computer to;
locate a first set of stripe images of the first stripe, wherein each image in the first set of stripe images is in the video frame output by a camera of the two or more cameras,locate a second set of stripe images of the second stripe, wherein each image in the second set of stripe images is in the video frame output by a camera of the two or more cameras,determine, for each image of the first set of stripe images, a first image line in the video frame containing the image, wherein the first image line prescribes a first plane in the volume;
determine, for each image of the second set of stripe images, a second image line in the video frame containing the image, wherein the second image line prescribes a second plane in the volume;
compute a first line of intersection of the first planes prescribed by at least two of the first image lines,compute a second line of intersection of the second planes prescribed by at least two of the second image lines,determine a transformation between the local coordinate system and the global coordinate system, wherein the transformation maps the first reference line to the first line of intersection, and wherein the transformation maps the second reference line to the second line of intersection, anddetermine from the transformation the position information about the first object.
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Abstract
A method or a system embodiment determines positional information about a moveable object to which is affixed a pattern of stripes having reference lines. A method determines image lines of stripe images of each stripe within at least two video frames, uses the image lines to prescribe planes having lines of intersection, and determines a transformation mapping reference lines to lines of intersection. Position information about the object may be derived from the transformation. A system embodiment comprises a pattern of stripes in a known fixed relationship to an object, reference lines characterizing the stripes, two or more cameras at known locations, a digital computer adapted to receive video frames from the pixel arrays of the cameras, and a program stored in the computer'"'"'s memory. The program performs some or all of the method. When there are two or more moveable objects, an embodiment may further determine the position information about a first object to be transformed to a local coordinate system fixed with respect to a second object.
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Citations
28 Claims
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1. A system for determining position information about a first object in a volume, comprising:
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a global coordinate system defined in the volume; a local coordinate system in a known fixed relationship to the first object; a pattern of two or more stripes in a fixed relationship to the first object, wherein a first stripe of the pattern is characterized by a first reference line defined relative to the local coordinate system, and a second stripe of the pattern is characterized by a second reference line defined relative to the local coordinate system; two or more cameras, wherein each camera can output a 2-dimensional video frame, and wherein each video frame has a known relationship to the global coordinate system; a digital computer adapted to receive the video frame output from each camera; and a memory connected to the computer and containing a program of instructions which cause the computer to; locate a first set of stripe images of the first stripe, wherein each image in the first set of stripe images is in the video frame output by a camera of the two or more cameras, locate a second set of stripe images of the second stripe, wherein each image in the second set of stripe images is in the video frame output by a camera of the two or more cameras, determine, for each image of the first set of stripe images, a first image line in the video frame containing the image, wherein the first image line prescribes a first plane in the volume; determine, for each image of the second set of stripe images, a second image line in the video frame containing the image, wherein the second image line prescribes a second plane in the volume; compute a first line of intersection of the first planes prescribed by at least two of the first image lines, compute a second line of intersection of the second planes prescribed by at least two of the second image lines, determine a transformation between the local coordinate system and the global coordinate system, wherein the transformation maps the first reference line to the first line of intersection, and wherein the transformation maps the second reference line to the second line of intersection, and determine from the transformation the position information about the first object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for determining positional information about a first object in a volume, comprising:
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defining a global coordinate system in the volume; defining a local coordinate system in a known fixed relationship to the first object; affixing a first pattern of two or more stripes in a relationship to the first object; characterizing a first stripe of the first pattern by a first reference line defined relative to the local coordinate system; characterizing a second stripe of the first pattern by a second reference line defined relative to the local coordinate system; positioning two or more cameras to view at least a portion of the volume; outputting a video frame from each of the two or more cameras, wherein each video frame has a known relationship to the volume; locating a first set of images of the first stripe, wherein each image in the first set of images is contained in the video frame output by a camera of the two or more cameras, locating a second set of images of the second stripe, wherein each image in the second set of images is contained in the video frame output by a camera of the two or more cameras, for each image in the first set of images, determining a first image line in the video frame containing the image, wherein the first image line prescribes a first plane in the volume; for each image in the second set of images, determining a second image line in the video frame containing the image, wherein the second image line prescribes a second plane in the volume; computing a first line of intersection of the first planes prescribed by at least two of the first image lines; computing a second line of intersection of the second planes prescribed by at least two of the second image lines; determining a transformation between the local coordinate system and the global coordinate system, wherein the transformation maps the first reference line to the first line of intersection, and wherein the transformation maps the second reference line to the second line of intersection; and determining the position information about the first object from the transformation. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification