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55
Determining the Epipolar Geometry and its Uncertainty: A Review
 International Journal of Computer Vision
, 1998
"... Two images of a single scene/object are related by the epipolar geometry, which can be described by a 3×3 singular matrix called the essential matrix if images' internal parameters are known, or the fundamental matrix otherwise. It captures all geometric information contained in two i ..."
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Cited by 340 (8 self)
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Two images of a single scene/object are related by the epipolar geometry, which can be described by a 3&times;3 singular matrix called the essential matrix if images' internal parameters are known, or the fundamental matrix otherwise. It captures all geometric information contained in two images, and its determination is very important in many applications such as scene modeling and vehicle navigation. This paper gives an introduction to the epipolar geometry, and provides a complete review of the current techniques for estimating the fundamental matrix and its uncertainty. A wellfounded measure is proposed to compare these techniques. Projective reconstruction is also reviewed. The software which we have developed for this review is available on the Internet.
Calibrationfree augmented reality
 IEEE Transactions on Visualization and Computer Graphics
, 1998
"... Abstract—Camera calibration and the acquisition of Euclidean 3D measurements have so far been considered necessary requirements for overlaying threedimensional graphical objects with live video. In this article, we describe a new approach to videobased augmented reality that avoids both requirement ..."
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Cited by 95 (0 self)
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Abstract—Camera calibration and the acquisition of Euclidean 3D measurements have so far been considered necessary requirements for overlaying threedimensional graphical objects with live video. In this article, we describe a new approach to videobased augmented reality that avoids both requirements: It does not use any metric information about the calibration parameters of the camera or the 3D locations and dimensions of the environment’s objects. The only requirement is the ability to track across frames at least four fiducial points that are specified by the user during system initialization and whose world coordinates are unknown. Our approach is based on the following observation: Given a set of four or more noncoplanar 3D points, the projection of all points in the set can be computed as a linear combination of the projections of just four of the points. We exploit this observation by 1) tracking regions and color fiducial points at frame rate, and 2) representing virtual objects in a nonEuclidean, affine frame of reference that allows their projection to be computed as a linear combination of the projection of the fiducial points. Experimental results on two augmented reality systems, one monitorbased and one headmounted, demonstrate that the approach is readily implementable, imposes minimal computational and hardware requirements, and generates realtime and accurate video overlays even when the camera parameters vary dynamically. Index Terms—Augmented reality, realtime computer vision, calibration, registration, affine representations, feature tracking, 3D interaction techniques.
Affine Structure from Line Correspondences with Uncalibrated Affine Cameras
 IEEE Trans. Pattern Analysis and Machine Intelligence
, 1997
"... This paper presents a linear algorithm for recovering 3D affine shape and motion from line correspondences with uncalibrated affine cameras. The algorithm requires a minimum of seven line correspondences over three views. The key idea is the introduction of a onedimensional projective camera. This ..."
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Cited by 78 (9 self)
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This paper presents a linear algorithm for recovering 3D affine shape and motion from line correspondences with uncalibrated affine cameras. The algorithm requires a minimum of seven line correspondences over three views. The key idea is the introduction of a onedimensional projective camera. This converts 3D affine reconstruction of "line directions" into 2D projective reconstruction of "points". In addition, a linebased factorisation method is also proposed to handle redundant views. Experimental results both on simulated and real image sequences validate the robustness and the accuracy of the algorithm.
Lines and Point in Three Views and the Trifocal Tensor
, 1997
"... This paper disc#274# the basic role of the trifoc al tensor insc#37 rec# nstr uc#r# n from three views. This 3 3 tensor plays a role in the analysis of sc#422 from three views analogous to the role played by the fundamental matrix in the twoviewc ase. In partic ular, the trifoc al tensor may ..."
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Cited by 77 (2 self)
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This paper disc#274# the basic role of the trifoc al tensor insc#37 rec# nstr uc#r# n from three views. This 3 3 tensor plays a role in the analysis of sc#422 from three views analogous to the role played by the fundamental matrix in the twoviewc ase. In partic ular, the trifoc al tensor may bec omputed by a linear algorithm from a set of 13 linec orrespondenc#3 in three views. It is further shown in this paper, that the trifoc al tensor is essentially identic## to a set ofc oe#c#99 ts introduc#5 by Shashua toe#ec# point transfer in the three viewc##22 This observation means that the 13line algorithm may be extended to allow for thec omputation of the trifoc al tensor given any mixture of su#c#36 tly many line and pointc orrespondenc#9# From the trifoc al tensor thec amera matric## of the images may be c#25371# and the sc#35 may berec#31#41562# For unrelatedunc# libratedc ameras, this rec# nstr uc#r# n will be unique up to projec#939# y. Thus, projec#61 e rec#376#39162 of a set of lines and points may bec#40940 out linearly from three views.
Euclidean Reconstruction from Constant Intrinsic Parameters
"... In this paper a new method for Euclidean reconstruction from sequences of images taken by uncalibrated cameras, with constant intrinsic parameters, is described. Our approach leads to a variant of the so called Kruppa equations. It is shown that it is possible to calculate the intrinsic parameters a ..."
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Cited by 74 (6 self)
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In this paper a new method for Euclidean reconstruction from sequences of images taken by uncalibrated cameras, with constant intrinsic parameters, is described. Our approach leads to a variant of the so called Kruppa equations. It is shown that it is possible to calculate the intrinsic parameters as well as the Euclidean reconstruction from at least three images. The novelty of our approach is that we build our calculation on a projective reconstruction, obtained without the assumption on constant intrinsic parameters. This assumption simplifies the analysis, because a projective reconstruction is already obtained and we need ‘only’ to find the correct Euclidean reconstruction among all possible projective reconstructions.
Parallax Geometry of Pairs of Points for 3D Scene Analysis
 In European Conference on Computer Vision
, 1996
"... this paper we develop geometric relationships between the residual (planar) parallax displacements of pairs of points. These geometric relationships address the problem of 3D scene analysis even in difficult conditions, i.e., when the epipole estimation is illconditioned, when there is a small numb ..."
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Cited by 59 (9 self)
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this paper we develop geometric relationships between the residual (planar) parallax displacements of pairs of points. These geometric relationships address the problem of 3D scene analysis even in difficult conditions, i.e., when the epipole estimation is illconditioned, when there is a small number of parallax vectors, and in the presence of moving objects. We show how these relationships can be applied to each of the three problems outlined at the beginning of this section. Moreover, the use of the parallax constraints derived here provides a continuum between "2D algorithms" and the "3D algorithms" for each of the problems mentioned above. The geometric relationships presented in this work are expressed in terms of residual parallax displacements of points after canceling a planar homography
Trilinear Tensor: The Fundamental Construct of Multipleview Geometry and its Applications
 INT. WORSKSHOP ON AFPAC
, 1997
"... The topic of representation, recovery and manipulation of threedimensional (3D) scenes from twodimensional (2D) images thereof, provides a fertile ground for both intellectual theoretically inclined questions related to the algebra and geometry of the problem and to practical applications such ..."
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Cited by 42 (8 self)
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The topic of representation, recovery and manipulation of threedimensional (3D) scenes from twodimensional (2D) images thereof, provides a fertile ground for both intellectual theoretically inclined questions related to the algebra and geometry of the problem and to practical applications such as Visual Recognition, Animation and View Synthesis, recovery of scene structure and camera egomotion, object detection and tracking, multisensor alignment, etc. The basic materials have been known since the turn of the century, but the full scope of the problem has been under intensive study since 1992, first on the algebra of two views and then on the algebra of multiple views leading to a relatively mature understanding of what is known as "multilinear matching constraints", and the "trilinear tensor" of three or more views. The purpose of this paper is, first and foremost, to provide a coherent framework for expressing the ideas behind the analysis of multiple views. Seco...
From Reference Frames to Reference Planes: MultiView Parallax Geometry and Applications
 In European Conference on Computer Vision
, 1998
"... This paper presents a new framework for analyzing the geometry of multiple 3D scene points from multiple uncalibrated images, based on decomposing the projection of these points on the images into two stages: (i) the projection of the scene points onto a (real or virtual) physical reference planar ..."
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Cited by 41 (7 self)
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This paper presents a new framework for analyzing the geometry of multiple 3D scene points from multiple uncalibrated images, based on decomposing the projection of these points on the images into two stages: (i) the projection of the scene points onto a (real or virtual) physical reference planar surface in the scene; this creates a virtual "image" on the reference plane, and (ii) the reprojection of the virtual image onto the actual image plane of the camera. The positions of the virtual image points are directly related to the 3D locations of the scene points and the camera centers relative to the reference plane alone. All dependency on the internal camera calibration parameters and the orientation of the camera are folded into homographies relating each image plane to the reference plane. Bilinear and trilinear constraints involving multiple points and views are given a concrete physical interpretation in terms of geometric relations on the physical reference plane. In particu...
GrassmannCayley algebra for modeling systems of cameras and the algebraic equations of the manifold of trifocal tensors
, 1997
"... We show how to use the GrassmannCayley algebra to model systems of one, two and three cameras. We start with a brief introduction of the GrassmannCayley or double algebra and proceed to demonstrate its use for modeling systems of cameras. In the case of three cameras, we give a new interpretation ..."
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Cited by 35 (0 self)
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We show how to use the GrassmannCayley algebra to model systems of one, two and three cameras. We start with a brief introduction of the GrassmannCayley or double algebra and proceed to demonstrate its use for modeling systems of cameras. In the case of three cameras, we give a new interpretation of the trifocal tensors and study in detail some of the constraints that they satisfy. In particular we prove that simple subsets of those constraints characterize the trifocal tensors, in other words, we give the algebraic equations of the manifold of trifocal tensors.
Estimating Motion and Structure from Correspondences of Line Segments Between Two Perspective Images
, 1994
"... We present in this paper an algorithm for determining 3D motion and structure from correspondences of line segments between two perspective images. To our knowledge, this paper is the first investigation on use of line segments in motion and structure from motion. Classical methods use their geometr ..."
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Cited by 32 (1 self)
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We present in this paper an algorithm for determining 3D motion and structure from correspondences of line segments between two perspective images. To our knowledge, this paper is the first investigation on use of line segments in motion and structure from motion. Classical methods use their geometric abstraction, namely straight lines, but then three images are necessary. We show in this paper that two views are in general sufficient when using line segments. The assumption we use is that two matched line segments contain the projection of a common part of the corresponding line segment in space. Indeed, this is what we use to match line segments between different views. Both synthetic and real data have been used to test the proposed algorithm, and excellent results have been obtained with real data containing about one hundred line segments. The results are comparable with those obtained with calibrated stereo.