Wyniki wyszukiwania - BazTech

1

Robust two-view reconstruction procedure for geometrical model retrieving

Walczak J., Wojciechowski A.

Journal of Applied Computer Science

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2018

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Vol. 26, nr 1

87--104

EN

In this paper we present the enhancement of the standard two-view reconstruction procedure. An ordinary approach assumes determination of points’ correspondences followed by projection matrix estimation, to finally refine results with bundle adjustment taking as a cost function reprojection error. Our contribution is realized in two manners: introducing an additional step of outliers rejection, changing cost function of bundle adjustment process to Relative Reprojection Error (R) and applying central difference as a method for Jacobian matrix approximation. Tests revealed gain in average R with lower variance, for confidence level of 0.95. Besides accuracy improvement, the suggested modifications supply the final result in the time virtually independent on initial object’s complexity and, in most cases, shorter than the standard approach.

2

Analysis of 3D photogrammetric reconstruction

Velichova D.

Journal Biuletyn of Polish Society for Geometry and Engineering Graphics

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2017

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Vol. 30

59--62

EN

Paper brings information about process of analytics reconstruction of 3D real data of objects selected from photographic images using software application CamWitt. Reconstruction algorithms are based on classical methods of photogrammetry and principles of epipolar geometry.

PL

W pracy podano analityczną metodę odtwarzania rzeczywistych danych 3D obiektów wybranych z obrazów fotograficznych za pomocą aplikacji CamWitt. Algorytmy rekonstrukcji oparte są na klasycznych metodach fotogrametrii i zasadach geometrii epipolarnej.

3

Quaternion epipolar decomposition for camera pose identification and animation

Skarbek W., Tomaszewski M.

Opto-Electronics Review

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2013

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Vol. 21, No. 1

63-78

EN

In the literature of computer vision, computer graphics and robotics, the use of quaternions is exclusively related to 3D rotation representation and interpolation. In this research we found how epipoles in multi-camera systems can be used to represent camera poses in the quaternion domain. The rotational quaternion is decomposed in two epipole rotational quaternions and one z axis rotational quaternion. Quadratic form of the essential matrix is also related to quaternion factors. Thus, five pose parameters are distributed into three independent rotational quaternions resulting in measurement error separation at camera pose identification and greater flexibility at virtual camera animation. The experimental results refer to the design of free viewpoint television.

4

W drodze do telewizji trójwymiarowej o swobodnym punkcie obserwacji

Tomaszewski M., Skarbek W.

Elektronika : konstrukcje, technologie, zastosowania

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2009

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Vol. 50, nr 4

84-91

PL

Praca dotyczy algorytmicznych podstaw systemu telewizji trójwymiarowej o swobodnym punkcie obserwacji (FVP-3D-TV). Proponowane są ulepszenia szeregu podstawowych komponentów systemu: identyfikacji macierzy istotnej, konstrukcji map dysparycji i nawigacji przestrzennej jako elementu interfejsu użytkownika. Wykorzystanie metody optymalizacji LMM (Levenberga Marquarda) oraz wielobiegunowej faktoryzacji kątowej macierzy istotnej, pozwoliło na 90% redukcję błędu w porównaniu do modelu początkowego otrzymywanego metodą ośmiu punktów. Tworzenie map dysparycji jest wspomagane przez rektyfikację (prostowanie) biegunową, uzyskaną przez liniową transformację w dziedzinie obrazu. Skutkuje to zmniejszeniem zniekształceń w stosunku do techniki rektyfikacji o biegunach w nieskończoności. Wreszcie zaproponowano przyjazny dla użytkownika trójwymiarowy model nawigacji, który został zorganizowany wokół dwubiegunowych linii bazowych kamer rzeczywistych. Rozwiązanie to pozwoliło na płynne przełączanie widoku pomiędzy kamerami, a trajektoria kamery wirtualnej przecinająca linię główną nie generuje zauważalnych artefaktów, pomimo pojawiających się osobliwości macierzowych.

EN

A general scheme of free view point 3D television system (FVP-3D-TV) is considered. It is based on image based rendering and epipolar geometry of cameras. Several enhancements are proposed for the system basic modules: essential matrix identification, disparity map construction, and 3D navigation model for user interface. The epipolar angular factorisation of essential matrix is used for nonlinear least squared optimization. It reduces about 90% of error w.r.t. the initial model obtained by eight-point algorithm. Disparity map construction is supported by polar rectification. It is produced by 2D linear transformation of image domains and for camera setups applied in FVP-3D-TV systems, exhibits less distortion than rectification by mapping epipoles to infinity. Finally, user friendly 3D navigation model for GUI is proposed. It is organised around the baselines of real cameras. Despite the singularity of essential matrix equations, the trajectory of virtual camera can intersect baselines without noticed artefacts, and smooth switch between cameras is provided.

5

3D measurements and motion analysis supported by passive vision techniques

Kohut P.

Computer Assisted Mechanics and Engineering Sciences

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2007

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Vol. 14, No. 4

637-649

EN

The article contains presentation of application of three-dimensional vision methods in realization of vibration measurements and their analysis. For this purpose algorithms were developed of discrete epipolar geometry and structure from motion, with the usage of one camera. Vibration amplitude is determined for selected measurement points on the analyzed object. Each point is represented by flat or three-dimensional marker attached on a construction. The article includes algorithms of the discussed methods and verification of those methods based upon simulation data, as we as preliminary experimental tests carried out on a test bed.

6

A complement to the 8 point algorith in matching uncalibrated image sequences of a scene

Tefera D. A., Harada K.

Machine Graphics and Vision

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2001

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Vol. 10, No. 1

15-28

EN

This paper presents an algorithm which generates an initial set of matching corner points between two uncalibrated images of the same scene. Matching different images of a single scene remains one of the bottlenecks in computer vision. The major part of matching algorithms is to recover the epipolar geometry, which heavily depends on the accuracy of the set of eigh corresponding points that are used to calculate the fundamental matrix between the sets of images under consideration. Thus, an algorithm to locate a reliable initial guess for matching corner points is proposed. The algorithm has been tested and shown reliable with different types of images indicating its ability to localize reliable sets of matching corner points. With the help of non-maximum response suppression technique our approach yields better results than other methods.

7

An active structure approach to stereo matching

Philipp M.

Machine Graphics and Vision

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2000

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Vol. 9, No. 3

633-645

EN

A new global method of image matching in stereopsis is proposed. It relies on the matching of points (tokens) belonging to image edges. The matching is based on the smooth disparity field constraint and the intensity-constancy constrain on the tokens using epipolar geometry. The paper describes the way the tokens are chosen and the matching prosedure. Results are presented for sample image pairs.

8

Hierarchical correspondance of gray connected components in stereo images using epipolar geometry

Wang Y., Bhattacharya P.

Machine Graphics and Vision

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1999

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Vol. 8, No. 1

19-54

EN

In this paper, we propose a new feature--based method for stereo matching. The matching primitives that we use are the boundaries of cerain parameter--dependet connected components of images. Under cerain assumptions, there is a one--to--one correspondence between subsets of the points on the boundaries of connected components of stereo pairs. This correspondance can be identified using the epipolar geometry. Using matched biundareies, we can identify the corresponding connected components determined by the boundaries. By changing the values of the parameters, we obtain a hierarchy of connected components in a gray image, which in turn provides us with a hierarchical stereo correspondance method.