Incremental motion estimation through local bundle adjustment
First Claim
1. A computer-implemented incremental motion estimation process for estimating camera pose parameters associated with each of a sequence of images of a scene, comprising using a computer to perform the following process actions:
- establishing a set of triple matching points that depict the same point in the scene across three successive images of each triplet of images that can be formed from the sequence;
establishing a set of dual matching points that depict the same point in the scene across the latter two images of each triplet of images that can be formed from the sequence;
defining camera coordinate system associated with the first image in the sequence as coinciding with a 3D world coordinate system for the scene depicted in the sequence of images;
estimating the camera pose parameters associated with the second image in the sequence; and
for each successive triplet of images formable from the sequence starting with the first three images, estimating the camera pose parameters associated with the third image of each triplet from previously-ascertained camera pose parameters associated with the first two images in the triplet, as well as the dual and triple matching points of the triplet, said estimating comprising, computing the camera pose parameters associated with the third image in the triplet under consideration which will result in a minimum value for a sum of the squared differences between the image coordinates of each identified triple match point and its corresponding predicted image coordinates in each of the three images in the triplet, added to a sum of the squared differences between the image coordinates of each identified dual match point and its corresponding predicted image coordinates in each of the latter two images in the triplet.
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Abstract
An incremental motion estimation system and process for estimating the camera pose parameters associated with each image of a long image sequence. Unlike previous approaches, which rely on point matches across three or more views, the present system and process also includes those points shared only by two views. The problem is formulated as a series of localized bundle adjustments in such a way that the estimated camera motions in the whole sequence are consistent with each other. The result of the inclusion of two-view matching points and the localized bundle adjustment approach is more accurate estimates of the camera pose parameters for each image in the sequence than previous incremental techniques, and providing an accuracy approaching that of global bundle adjustment techniques except with processing times about 100 to 700 times faster than the global approaches.
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Citations
8 Claims
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1. A computer-implemented incremental motion estimation process for estimating camera pose parameters associated with each of a sequence of images of a scene, comprising using a computer to perform the following process actions:
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establishing a set of triple matching points that depict the same point in the scene across three successive images of each triplet of images that can be formed from the sequence;
establishing a set of dual matching points that depict the same point in the scene across the latter two images of each triplet of images that can be formed from the sequence;
defining camera coordinate system associated with the first image in the sequence as coinciding with a 3D world coordinate system for the scene depicted in the sequence of images;
estimating the camera pose parameters associated with the second image in the sequence; and
for each successive triplet of images formable from the sequence starting with the first three images, estimating the camera pose parameters associated with the third image of each triplet from previously-ascertained camera pose parameters associated with the first two images in the triplet, as well as the dual and triple matching points of the triplet, said estimating comprising, computing the camera pose parameters associated with the third image in the triplet under consideration which will result in a minimum value for a sum of the squared differences between the image coordinates of each identified triple match point and its corresponding predicted image coordinates in each of the three images in the triplet, added to a sum of the squared differences between the image coordinates of each identified dual match point and its corresponding predicted image coordinates in each of the latter two images in the triplet. - View Dependent Claims (2, 3, 4, 5)
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6. A local bundling adjustment system for estimating the camera projection matrix associated with each of a sequence of images of a scene, comprising:
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a general purpose computing device;
a computer program comprising program modules executable by the computing device, wherein the computing device is directed by the program modules of the computer program to, input the sequence of images, identify points in each image in the sequence of images, determine which of the identified points depict the same point of the scene so as to be matching points, said determining comprising, establishing a set of triple matching points that depict the same point in the scene across the three successive images of each triplet of images that can be formed from the sequence, and establishing a set of dual matching points that depict the same point in the scene across the latter two images of each triplet of images that can be formed from the sequence, define the camera coordinate system associated with the first image in the sequence as coinciding with a 3D world coordinate system for the scene depicted in the sequence of images, compute the camera projection matrix associated with the second image in the sequence, and for each successive triplet of images that can be formed from the sequence starting with the first three images, estimate the camera projection matrix of the third image of each triplet from previously-ascertained camera projection matrices associated with the first two images in the triplet as well as points determined to be matching points across all three images of the of the triplet and points determined to be matching points across at least one pair of images in the triplet, said estimating comprising, computing the camera projection matrix associated with the third image in the triplet under consideration which will result in a minimum value for the sum of the squared differences between the image coordinates of each identified triple match point and its corresponding predicted image coordinates in each of the three images in the triplet, added to the sum of the squared differences between the image coordinates of each identified dual match point and its corresponding predicted image coordinates in each of the latter two images in the triplet.
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7. A local bundle adjustment process for estimating the camera pose parameters associated with each of a sequence of images of a scene, comprising the following process actions:
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identifying points in each image in the sequence of images;
determining which of the identified points depict the same point of the scene so as to be matching points, said determining comprising, establishing a set of triple matching points {(p0,j, p1,j, p2,j)|j=1, . . . , M} that depict the same point in the scene across the three successive images of each triplet of images that can be formed from the sequence, where j refers to a particular instance of a triple matching point and M refers to the total number of triple matching points in the set, and establishing a set of dual matching points {(q1,k, q2,k)|k=1, . . . , N} that depict the same point in the scene across the latter two images of each triplet of images that can be formed from the sequence, where k refers to a particular instance of a dual matching point and N refers to the total number of dual matching points in the set;
defining the camera coordinate system associated with the first image in the sequence as coinciding with a 3D world coordinate system for the scene depicted in the sequence of images;
computing the camera pose parameters associated with the second image in the sequence; and
for each successive triplet of images that can be formed from the sequence starting with the first three images, estimate the camera pose parameters of the third image of each triplet from previously-ascertained camera pose parameters associated with the first two images in the triplet as well as points determined to be matching points across all three images of the triplet and points determined to be matching points across at least one pair of images in the triplet, said estimating comprising, computing the 3D world coordinates associated with each triple and dual match point in the triplet, as well as the camera pose parameters associated with the third image in the triplet under consideration, which will result in a minimum value according to the equation, where i refers to the images of the triplet under consideration such that i=0 is the first image , i=1 is the second image and i=2 is the third image, Mi refers to the camera pose parameters of the ith image in the, Pj is the 3D point corresponding to triple point match (p0,j, p1,j, p2,j), Qk is the 3D point corresponding to pair point match (q1,k, q2,k), φ
(Mj, Pj) represents the predicted image coordinates of the triple matching point pi,j as a function of the 3D world coordinates associated with the triple matching point under consideration and the camera pose parameters of the image containing this triple matching point, and φ
(Mi, Qk) represents the predicted image coordinates of dual matching point qi,k as a function of the 3D world coordinates associated with the dual matching point under consideration and the camera pose parameters of the image containing this dual matching point.- View Dependent Claims (8)
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Specification