Determining camera height using distributions of object heights and object image heights
First Claim
1. A method for determining a height of a camera, the camera at an unknown fixed vertical height positioned above a reference plane, and having an axis of a lens of the camera at an acute angle with respect to a perpendicular of the reference plane, the method comprising the steps of:
- receiving from the camera, by one or more processors, over a specified time period, a multiplicity of images of a multiplicity of people of unknown height within a field of view of the camera;
determining, by one or more processors, vertical measurement values of the multiplicity of images of the multiplicity of people of unknown height, wherein each vertical measurement value includes a pixel count along a vertical axis of an image of the multiplicity of images of the multiplicity of people of unknown height;
receiving, by one or more processors, heights of a multiplicity of people from a statistical distribution of known heights of people;
transforming, by one or more processors, the known heights of the multiplicity of people from the statistical distribution of known heights of people to normalized vertical measurement values that includes a pixel count, based at least on a focal length of the lens of the camera, the acute angle of the camera, and a division operator present in an objective function;
performing, by one or more processors, the objective function to sum differences between the pixel count of the vertical measurement values of the multiplicity of images and the pixel count of the normalized vertical measurement values of the heights of the multiplicity of people from the statistical distribution of the known heights of people, wherein the objective function includes an estimate of the fixed vertical height of the camera, and a transformation matrix to convert the known heights of people to normalized vertical measurement values; and
determining, by one or more processors, the fixed vertical height of the camera by adjusting within the objective function, the estimate of the fixed vertical height of the camera, until a result of the objective function is minimized.
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Abstract
A camera at a fixed vertical height positioned above a reference plane, with an axis of a camera lens at an acute angle with respect to a perpendicular of the reference plane. One or more processors receive images of different people. The vertical measurement values of the images of different people are determined. The one or more processors determine a first statistical measure associated with a statistical distribution of the vertical measurement values. The known heights of people from a known statistical distribution of heights of people are transformed to normalized measurements, based in part on a focal length of the camera lens, the angle of the camera, and a division operator in an objective function of differences between the normalized measurements and the vertical measurement values. The fixed vertical height of the camera is determined, based at least on minimizing the objective function.
15 Citations
20 Claims
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1. A method for determining a height of a camera, the camera at an unknown fixed vertical height positioned above a reference plane, and having an axis of a lens of the camera at an acute angle with respect to a perpendicular of the reference plane, the method comprising the steps of:
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receiving from the camera, by one or more processors, over a specified time period, a multiplicity of images of a multiplicity of people of unknown height within a field of view of the camera; determining, by one or more processors, vertical measurement values of the multiplicity of images of the multiplicity of people of unknown height, wherein each vertical measurement value includes a pixel count along a vertical axis of an image of the multiplicity of images of the multiplicity of people of unknown height; receiving, by one or more processors, heights of a multiplicity of people from a statistical distribution of known heights of people; transforming, by one or more processors, the known heights of the multiplicity of people from the statistical distribution of known heights of people to normalized vertical measurement values that includes a pixel count, based at least on a focal length of the lens of the camera, the acute angle of the camera, and a division operator present in an objective function; performing, by one or more processors, the objective function to sum differences between the pixel count of the vertical measurement values of the multiplicity of images and the pixel count of the normalized vertical measurement values of the heights of the multiplicity of people from the statistical distribution of the known heights of people, wherein the objective function includes an estimate of the fixed vertical height of the camera, and a transformation matrix to convert the known heights of people to normalized vertical measurement values; and determining, by one or more processors, the fixed vertical height of the camera by adjusting within the objective function, the estimate of the fixed vertical height of the camera, until a result of the objective function is minimized. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer program product for determining a height of a camera, the camera at an unknown fixed vertical height positioned above a reference plane, and having an axis of a lens of the camera at an acute angle with respect to a perpendicular of the reference plane, the computer program product comprising:
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one or more non-transitory computer-readable storage media and program instructions stored on the one or more non-transitory computer-readable storage media, the program instructions comprising; program instructions to receive from the camera, over a specified time period, a multiplicity of images of a multiplicity of people of unknown height, within a field of view of the camera; program instructions to determine vertical measurement values of the multiplicity of images from the camera of the multiplicity of people of unknown height, wherein each vertical measurement value includes a pixel count along a vertical axis of an image of the multiplicity of images of the multiplicity of people of unknown height; program instructions to receive heights of a multiplicity of people from a statistical distribution of known heights of people; program instructions to transform the known heights of the multiplicity of people from the statistical distribution of known heights of people to normalized vertical measurement values that includes a pixel count based at least on a focal length of the lens of the camera, the acute angle of the camera, and a division operator present in an objective function; program instructions to perform the objective function to sum differences between the pixel count of the vertical measurement values of the multiplicity of images and the pixel count of the normalized vertical measurement values of heights of the multiplicity of people from the distribution data of the known heights of people, wherein the objective function includes an estimate of the fixed vertical height of the camera, and a transformation matrix to convert the known heights of people to normalized vertical measurement values; and program instructions to determine the fixed vertical height of the camera by adjusting within the objective function, the estimate of the fixed vertical height of the camera, until a result of the objective function is minimized. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A computer system for determining a height of a camera, the camera at an unknown fixed vertical height positioned above a reference plane, and having an axis of a lens of the camera at an acute angle with respect to a perpendicular of the reference plane, the computer system comprising:
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one or more computer processors; one or more computer-readable memories; one or more non-transitory computer-readable storage media; program instructions stored on the one or more non-transitory computer-readable storage media for execution by the one or more processors via the one or more computer-readable memories, the program instructions comprising; program instructions to receive from the camera, over a specified time period, a multiplicity of images of a multiplicity of people of unknown height, within a field of view of the camera; program instructions to determine vertical measurement values of the multiplicity of images from the camera of the multiplicity of people of unknown height, wherein each vertical measurement value includes a pixel count along a vertical axis of an image of the multiplicity of images of the multiplicity of people of unknown height; program instructions to receive heights of a multiplicity of people from a statistical distribution of known heights of people; program instructions to transform the known heights of the multiplicity of people from the statistical distribution of known heights of people to normalized vertical measurement values that includes a pixel count based at least on a focal length of the lens of the camera, the acute angle of the camera, and a division operator present in an objective function, wherein the objective function includes an estimate of the fixed vertical height of the camera, and a transformation matrix to convert the known heights of people to normalized vertical measurement values; program instructions to perform the objective function to sum differences between the pixel count of the vertical measurement values of the multiplicity of images and the pixel count of the normalized vertical measurement values of the heights of the multiplicity of people from the distribution of the known heights of people; and program instructions to determine the fixed vertical height of the camera by adjusting within the objective function, the estimate of the fixed vertical height of the camera, until a result of the objective function is minimized. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification