US2013176432A1PendingUtilityA1
Automatic calibration of ptz camera system
Est. expiryAug 8, 2028(~2.1 yrs left)· nominal 20-yr term from priority
Inventors:Himaanshu GuptaAndrew J. ChosakGeoffrey Richard TaylorPaul C. BrewerNiels HaeringAlan J. Lipton
G08B 13/1963H04N 17/002
53
PatentIndex Score
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Claims
Abstract
A method to determine a base focal length of a pan-tilt-zoom (PTZ) camera system. The method includes generating a spherical mosaic with a feature track by the camera system and determining, by the camera system, a base focal length by analyzing a conic trajectory created by the feature track on an image plane.
Claims
exact text as granted — not AI-modified1 ) A method of determining a base focal length of a pan-tilt-zoom (PTZ) camera system comprising:
generating a spherical mosaic with a feature track by the camera system; and determining, by the camera system, a base focal length by analyzing a conic trajectory created by the feature track on an image plane.
2 ) The method of claim 1 , wherein the base focal length is characterized by the equation
(
f
,
θ
,
ψ
)
=
argmin
f
,
θ
,
ψ
∑
j
e
^
j
2
(
x
i
,
j
,
f
,
θ
,
ψ
)
where f is the base focal length, θ is a tilt, ψ is a roll, x i,j is a set of image plane measurements on the conic for the j th feature, and ê 2 is a minimum residual error.
3 ) One or more tangible non-transitory computer-readable storage media for storing computer-executable instructions executable by a computer system, the media storing one or more instructions for:
generating a spherical mosaic with a feature track; and determining a base focal length for a pan-tilt-zoom (PTZ) camera by analyzing a conic trajectory created by the feature track on an image plane.
4 ) The non-transitory computer-readable storage media of claim 3 , wherein the base focal length is characterized by the equation
(
f
,
θ
,
ψ
)
=
argmin
f
,
θ
,
ψ
∑
j
e
^
j
2
(
x
i
,
j
,
f
,
θ
,
ψ
)
where f is the base focal length, θ is a tilt, ψ is a roll, x i,j is a set of image plane measurements on the conic for the j th feature, and ê 2 is a minimum residual error.
5 ) A pan-tilt-zoom (PTZ) camera calibration system comprising:
a PTZ camera; and a mosaic generation engine to generate a spherical mosaic with a feature track; and a base focal length engine to determine a base focal length of the PTZ camera by analyzing a conic trajectory created by the feature track on an image plane.
6 ) The PTZ camera calibration system of claim 5 , wherein the base focal length is characterized by the equation
(
f
,
θ
,
ψ
)
=
argmin
f
,
θ
,
ψ
∑
j
e
^
j
2
(
x
i
,
j
,
f
,
θ
,
ψ
)
where f is the base focal length, θ is a tilt, ψ is a roll, x i,j is a set of image plane measurements on the conic for the j th feature, and ê 2 is a minimum residual error.
7 ) A method of determining a radial distortion of a pan-tilt-zoom (PTZ) camera system comprising:
generating a spherical mosaic by the camera system; identifying sets of feature points from the spherical mosaic by the camera system; determining a range of reasonable radial distortion coefficients by the camera system; warping one or more sets of feature points according to the determined range of reasonable radial distortion coefficients by the camera system; determining a planar homography for one or more sets of warped feature points by the camera system; determining a reprojection error for one or more planar homographies by the camera system; and determining the radial distortion coefficient for one or more sets of feature points by the camera system.
8 ) The method of claim 7 , wherein the radial distortion coefficient for one or more sets of feature points is characterized by the equation
k
^
=
argmin
k
∑
s
∑
i
x
u
(
x
s
,
i
,
k
)
-
H
s
x
u
(
x
s
,
i
′
,
k
)
2
where k is the radial distortion coefficient, x u is the ideal projection of a point an image plane, s is a pair of feature points, x s,i and x′ s,i represent the i th corresponding feature point pair in set s, and H s is the planar homography.
9 ) One or more tangible non-transitory computer-readable storage media for storing computer-executable instructions executable by a computer system, the media storing one or more instructions for:
generating a spherical mosaic; identifying sets of feature points from the spherical mosaic; determining a range of reasonable radial distortion coefficients; warping one or more sets of feature points according to the determined range of reasonable radial distortion coefficients; determining a planar homography for one or more sets of warped feature points; determining a reprojection error for one or more planar homographies; and determining a radial distortion coefficient for one or more sets of feature points.
10 ) The non-transitory computer-readable storage media of claim 9 , wherein the radial distortion coefficient for one or more sets of feature points is characterized by the equation
k
^
=
argmin
k
∑
s
∑
i
x
u
(
x
s
,
i
,
k
)
-
H
s
x
u
(
x
s
,
i
′
,
k
)
2
where k is the radial distortion coefficient, x u is the ideal projection of a point an image plane, s is a pair of feature points, x s,i and x′ s,i represent the i th corresponding feature point pair in set s, and H s is the planar homography.
11 ) A pan-tilt-zoom (PTZ) camera calibration system comprising:
a PTZ camera; a mosaic construction engine to generate a spherical mosaic; a mosaic feature point engine to identify sets of feature points from the spherical mosaic; and a radial distortion engine to:
determine a range of reasonable radial distortion coefficients,
warp one or more sets of feature points according to the determined range of reasonable radial distortion coefficients,
determine a planar homography for one or more sets of warped feature points,
determine a reprojection error for one or more planar homographies, and
determine a radial distortion coefficient for one or more sets of feature points.
12 ) The PTZ camera calibration system of claim 11 , wherein the radial distortion coefficient for one or more sets of feature points is characterized by the equation
k
^
=
argmin
k
∑
s
∑
i
x
u
(
x
s
,
i
,
k
)
-
H
s
x
u
(
x
s
,
i
′
,
k
)
2
where k is the radial distortion coefficient, x u is the ideal projection of a point an image plane, s is a pair of feature points, x s,i and x′ s,i represent the i th corresponding feature point pair in set s, and H s is the planar homography.
13 ) A method of determining a zoom and magnification profile of a pan-tilt-zoom (PTZ) camera in a camera system comprising:
executing a plurality of zoom commands with the PTZ camera, wherein a first zoom command of the plurality of zoom commands sets the PTZ camera to a starting zoom level; capturing a plurality of images with the PTZ camera, wherein images in the plurality of images are captured after a zoom command from the plurality of zoom commands has been executed; estimating, by the camera system, a plurality of image magnifications based on images from the plurality of images; and determining, by the camera system, a zoom and magnification profile of the PTZ camera based on the plurality of image magnifications and the plurality of zoom commands.
14 ) The method of claim 13 , wherein estimating a plurality of image magnifications comprises comparing, by the camera system, a first image from the plurality of images to a second image from the plurality of images, wherein the second image is captured subsequent to the first image.
15 ) The method of claim 14 , wherein comparing comprises analyzing images and determining magnification using computer-based image processing.
16 ) One or more tangible non-transitory computer-readable storage media for storing computer-executable instructions executable by a computer system, the media storing one or more instructions for:
executing a plurality of zoom commands with a PTZ camera, wherein a first zoom command of the plurality of zoom commands sets the PTZ camera to a starting zoom level; capturing a plurality of images with the PTZ camera, wherein images in the plurality of images are captured after a zoom command from the plurality of zoom commands has been executed; estimating a plurality of image magnifications based on images from the plurality of images; and determining a zoom and magnification profile of the PTZ camera based on the plurality of image magnifications and the plurality of zoom commands.
17 ) The non-transitory computer-readable storage media of claim 16 , wherein estimating a plurality of image magnifications comprises comparing, by the camera system, a first image from the plurality of images to a second image from the plurality of images, wherein the second image is captured subsequent to the first image.
18 ) The non-transitory computer-readable storage media of claim 17 , wherein comparing comprises analyzing images and determining magnification using computer-based image processing.
19 ) A pan-tilt-zoom (PTZ) camera calibration system comprising:
a PTZ camera; and a zoom and magnification engine to:
execute a plurality of zoom commands with the PTZ camera, wherein a first zoom command of the plurality of zoom commands sets the PTZ camera to a starting zoom level,
capture a plurality of images with the PTZ camera, wherein images in the plurality of images are captured after a zoom command from the plurality of zoom commands has been executed,
estimate a plurality of image magnifications based on images from the plurality of images, and
determine a zoom and magnification profile of the PTZ camera based on the plurality of image magnifications and the plurality of zoom commands.
20 ) The PTZ camera calibration system of claim 19 , wherein estimating a plurality of image magnifications comprises comparing, by the camera system, a first image from the plurality of images to a second image from the plurality of images, wherein the second image is captured subsequent to the first image.
21 ) The PTZ camera calibration system of claim 20 , wherein comparing comprises analyzing images and determining magnification using computer-based image processing.
22 ) A method of determining an actuation delay of a pan-tilt-zoom (PTZ) camera in a camera system, the method comprising:
issuing a velocity command to the PTZ camera by the camera system; capturing successive frames from the PTZ camera by the camera system; detecting PTZ camera motion by comparing successive captured frames by the camera system; and determining an actuation delay of the PTZ camera by the camera system, wherein the actuation delay is the amount of time between issuing the velocity command to the PTZ camera and observing PTZ camera motion.
23 ) The method of claim 22 , further comprising:
sending a query command to the PTZ camera; receiving a response to the query command from the PTZ camera; and determining the query delay of the PTZ camera, wherein the query delay is the amount of time between sending the query command and receiving the response to the query command.
24 ) The method of claim 22 , further comprising:
(a) sending a first query command to the PTZ camera; (b) sending a second query command to the PTZ camera after the expiration of a wait interval; (c) receiving a response to the second query command; (d) determining whether the received response comprises a valid response to the second query command and setting the minimum query interval equal to the wait interval when the minimum query interval comprises the valid response to the second query command; and (e) increasing the wait interval and repeating steps (a) through (d) when a non-valid response to the second query command is received.
25 ) One or more tangible non-transitory computer-readable storage media for storing computer-executable instructions executable by a computer system, the media storing one or more instructions for:
issuing a velocity command to the PTZ camera; capturing successive frames from the PTZ camera; detecting PTZ camera motion by comparing successive captured frames; and determining an actuation delay of the PTZ camera, wherein the actuation delay is the amount of time between issuing the velocity command to the PTZ camera and observing PTZ camera motion.
26 ) The non-transitory computer-readable storage media of claim 25 , further comprising:
sending a query command to the PTZ camera; receiving a response to the query command from the PTZ camera; and determining the query delay of the PTZ camera, wherein the query delay is the amount of time between sending the query command and receiving the response to the query command.
27 ) The non-transitory computer-readable storage media of claim 25 , further comprising:
(a) sending a first query command to the PTZ camera; (b) sending a second query command to the PTZ camera after the expiration of a wait interval; (c) receiving a response to the second query command; (d) determining whether the received response comprises a valid response to the second query command and setting the minimum query interval equal to the wait interval when the minimum query interval comprises the valid response to the second query command; and (e) increasing the wait interval and repeating steps (a) through (d) when a non-valid response to the second query command is received.
28 ) A pan-tilt-zoom (PTZ) camera calibration system comprising:
a PTZ camera; and an actuation delay engine to:
issue a velocity command to the PTZ camera,
capture successive frames from the PTZ camera,
detect PTZ camera motion by comparing successive captured frames, and
determine an actuation delay of the PTZ camera, wherein the actuation delay is the amount of time between issuing the velocity command to the PTZ camera and observing PTZ camera motion.
29 ) The system of claim 28 , further comprising:
a query delay engine to:
send a query command to the PTZ camera,
receive a response to the query command from the PTZ camera, and
determine the query delay of the PTZ camera, wherein the query delay is the amount of time between sending the query command and receiving the response to the query command.
30 ) The system of claim 28 , further comprising:
a minimum query interval engine to:
(a) send a first query command to the PTZ camera;
(b) send a second query command to the PTZ camera after the expiration of a wait interval;
(c) receive a response to the second query command;
(d) determine whether the received response comprises a valid response to the second query command and setting the minimum query interval equal to the wait interval when the minimum query interval comprises the valid response to the second query command; and
(e) increase the wait interval and repeating steps (a) through (d) when a non-valid response to the second query command is received.Cited by (0)
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