Position determination
First Claim
Patent Images
1. A method of determining the three-dimensional position of an object in a reference frame, the method comprising:
- providing three or more markers at respective reference positions, at least three of the markers being patterned as a series of concentric shapes encoding a plurality of bits of identification information in the darkness or color of the shapes, the center of the concentric shapes of each patterned marker providing a reference point for each marker, wherein each marker has a respective distance from a reference plane of the reference frame, the distances varying between the markers;
storing information including a measure of the three-dimensional positions of the markers in the reference frame and information identifying the patterned markers;
obtaining an image of at least a sub-set of said markers from a camera associated with the object;
processing the image to identify the positions of said markers in the image and, for each patterned marker in the sub-set, identifying the respective reference point and decoding said identification information;
determining a measure of the three-dimensional position of the object in the reference frame based on said processing and decoding and based on said stored information.
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Abstract
In the preferred implementation, the position of an object, for example a studio camera is determined by means of a camera which views several markers disposed about a studio ceiling, the markers being patterened as a series of light and dark rings to encode information in binary form enabling the markers to be identified as the camera moves about the studio. Methods and apparatus of more general applicability are also disclosed.
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Citations
44 Claims
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1. A method of determining the three-dimensional position of an object in a reference frame, the method comprising:
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providing three or more markers at respective reference positions, at least three of the markers being patterned as a series of concentric shapes encoding a plurality of bits of identification information in the darkness or color of the shapes, the center of the concentric shapes of each patterned marker providing a reference point for each marker, wherein each marker has a respective distance from a reference plane of the reference frame, the distances varying between the markers;
storing information including a measure of the three-dimensional positions of the markers in the reference frame and information identifying the patterned markers;
obtaining an image of at least a sub-set of said markers from a camera associated with the object;
processing the image to identify the positions of said markers in the image and, for each patterned marker in the sub-set, identifying the respective reference point and decoding said identification information;
determining a measure of the three-dimensional position of the object in the reference frame based on said processing and decoding and based on said stored information. - View Dependent Claims (2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 24, 25, 36, 40, 41, 42, 43, 44)
dynamically applying correction factors to said initial marker positions to produce respective corrected marker positions;
determining the object position based on the corrected marker positions, wherein said dynamically applying correction factors comprises calculating correction factors so that the corrected marker positions are corrected to become mutually self-consistent values, the rate of variation of the correction factors being limited to a pre-determined level by limiting the rate of change of correction factors.
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24. A method according to claim 1, wherein said object is a video camera having a field of view differing from the field of view of said camera.
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25. A method according to claim 24 further comprising providing at least one supplementary marker at a given position so as to be viewable by the video camera, the or each marker having identification information encoded thereon in binary form as a series of concentric rings of two tones, the tones being selected to enable the marker to be keyed out of the video camera image by chroma-keying, said determining the position of the video camera being based on the position of the supplementary marker, if present, in the video camera image.
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36. A set of at least three patterned markers mountable in a reference frame to enable the three-dimensional position of an object with respect to the reference frame to be determined in accordance with the method of claim 1, each marker comprising a series of concentric rings, each marker encoding an identifier of the marker as a plurality of bits of information in binary form as the brightness or reflectivity and/or thickness of each ring, the identifier of the markers varying between the markers, the center of the rings providing a reference point for the markers.
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40. A virtual production studio having at least three patterned markers mounted on the ceiling thereof at mutually different distances from the ceiling to enable the three-dimensional position of an object with respect to the studio reference frame to be determined in accordance with the method of claim 1, each marker comprising a series of concentric rings, each marker encoding an identifier of the marker as a plurality of bits of information in binary form as the brightness or reflectivity and/or thickness of each ring, the identifier of the markers varying between the markers, the center of the rings providing a reference point for the markers.
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41. A virtual production studio according to claim 40, having at least 10 markers mounted on the ceiling thereof.
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42. A virtual production studio according to claim 40 including a store of the three-dimensional positions and identifiers of the markers for use in position determination.
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43. A virtual production studio according to claim 40 including at least one studio camera arranged to capture a subject in a working space of the studio, the studio camera having apparatus for determination of the three-dimensional position of the studio camera in the studio reference frame, the apparatus for determination of the three-dimensional position comprising:
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a camera for mounting on the studio camera and arranged to point upwards at the markers when the studio camera is upright and pointed at a subject in said working space;
a memory storing measures of the three-dimensional positions of said markers in the reference frame and to store information identifying patterned encoded markers which markers comprise a series of concentric shapes encoding identification information as the darkness or color of shapes, the center of the concentric shapes of each patterned marker providing a reference point for each marker;
image processing means arranged to process an image output by the camera to identify the positions of markers in the image, to decode information encoded in the patterned markers and to determine the position of said reference points; and
position determining means arranged to determine the three-dimensional position of the studio camera in the studio reference frame based on the output of the image processing means and the information stored in the memory means.
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44. A method of providing a virtual production, the method comprising determining the position of a video camera in accordance with claim 24;
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applying a video effect to the output of the video camera based on the determined position.
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3. A method of determining the three-dimensional position of an object in a reference frame, the method comprising:
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providing three or more markers at respective reference positions, at least three of the markers being patterned to encode a plurality of bits of identification information in binary form in a series of concentric light and dark regions, the center of the concentric regions providing a reference point, wherein each marker has a respective distance from a reference plane of the reference frame, the distances varying between the markers;
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storing information including a measure of the three-dimensional positions of the markers in the reference frame and information identifying the patterned markers;
obtaining an image of at least a sub-set of said plurality of markers from a camera associated with the object;
processing the image to identify the positions of said markers in the image and, for each patterned marker in the sub-set, decoding said identification information and identifying the reference point; and
determining a measure of the three-dimensional position of the object in the reference frame based on said processing and decoding and based on said stored information. - View Dependent Claims (4, 39)
providing mutually different identifiers to be encoded in binary form; and
providing on a mountable backing a series of concentric shapes, each shape having either a high or a low brightness or reflectivity, the thickness or brightness or reflectivity of each ring shape selected according to a pre-determined coding scheme to encode the information, wherein the center of the shapes provides a reference point.
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39. A method according to claim 3, wherein the reference frame comprises a production studio having at least 10 markers positioned on the ceiling thereof, wherein the camera is an upward-pointing camera mounted on a studio camera.
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20. A method of determining the position of an object based on identification of a plurality of markers at respective reference positions, the method comprising:
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storing pre-stored or measured marker positions as initial marker positions;
dynamically applying correction factors to said initial marker positions to produce respective corrected marker positions;
determining the object position based on the corrected marker positions, wherein said dynamically applying correction factors comprises calculating correction factors so that the corrected marker positions are corrected to become mutually self-consistent values, a rate of variation of the correction factors being limited to a pre-determined level by limiting the rate of change of correction factors. - View Dependent Claims (21, 22, 23)
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26. Apparatus for determination of the three-dimensional position of an object in a reference frame, the apparatus comprising:
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a camera for mounting on an object whose position is to be determined;
a memory arranged to store measures of the three-dimensional positions of at least three markers in the reference frame and to store information identifying patterned encoded markers which markers comprise a series of concentric shapes encoding identification information as the darkness or color of the shapes, the center of the concentric shapes of each patterned marker providing a reference point for each marker;
image processing means arranged to process an image output by the camera to identify the positions of markers in the image, to decode information encoded in the patterned markers and to determine the position of said reference points; and
position determining means arranged to determine the three-dimensional position of the object in the reference frame based on the output of the image processing means and the information stored in the memory means. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35)
further memory for storing pre-stored or measured marker positions as initial marker positions;
means for dynamically applying correction factors to said initial marker positions to produce respective corrected marker positions;
means for determining the object position based on the corrected marker positions, wherein said means for dynamically applying correction factors comprises means for calculating correction factors so that the corrected marker positions are corrected to become mutually self-consistent values, the rate of variation of the correction factors being limited to a pre-determined level by limiting the rate of change of correction factors.
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34. Apparatus according to claim 26 arranged to determine the position of a video camera wherein said camera comprises a further camera mounted on the video camera, said camera facing in a different direction to the video camera.
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35. Apparatus according to claim 34, including means for detecting the zoom and/or focus settings of the video camera.
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37. Marker apparatus for positioning in the field of view of a video camera for use in determining the relative position of the camera and the marker apparatus, the apparatus comprising:
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a base;
a first patterned marker mounted at a first predetermined relative positions on a substantially rigid base, the first patterned marker having identification information encoded thereon in binary form as a series of concentric rings of two tones, the tones being selected to enable the marker to be keyed out of the video camera image by chroma-keying, the center of the rings providing a reference point for the marker, the first marker being at a first height from the base;
a second patterned marker mounted at a second predetermined relative positions on a substantially rigid base, the second patterned marker having identification information encoded thereon in binary form as a series of concentric rings of two tones, the tones being selected to enable the marker to be keyed out of the video camera image by chroma-keying, the center of the rings providing a reference point for the marker, the second marker being at a second height from the base;
a third patterned marker mounted at a third predetermined relative positions on a substantially rigid base, the third patterned marker having identification information encoded thereon in binary form as a series of concentric rings of two tones, the tones being selected to enable the marker to be keyed out of the video camera image by chroma-keying, the center of the rings providing a reference point for the marker, the third marker being at a third height from the base;
whereinsaid first height, said second height and said third height are all mutually different, whereby a three dimensional position fix relative to the base can be obtained from the markers.
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38. A method of determining the relative three-dimensional positions of at least one camera and an object having at least three markers mounted thereon, the relative positions of the markers and the object being substantially fixed, each marker being patterned to encode identification information in binary form as the darkness or color of a series of concentric rings, the center of the rings providing a reference point, the method comprising:
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storing the relative three dimensional positions of the markers with respect to the object and information enabling the identification information to be decoded;
receiving an image from the camera;
identifying the positions of the markers in the camera image;
decoding the identification information encoded on each marker;
determining the position of the reference point for each marker; and
based on the stored information, determining a measure of the relative three-dimensional positions and orientations of said at least one camera and object.
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Specification