EVOLUTION AND OPTIMUM SEEKING
von Hans-Paul Schwefel
Luis Alvarez et al. "An Algebraic Approach to Lens Distortion by Line Rectification" (0) | 2010.06.22 |
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Lens Distortion (0) | 2010.06.22 |
E. Trucco and A. Verri <Introductory Techniques for 3-D Computer Vision> (0) | 2010.06.14 |
pinhole camera model (0) | 2010.06.14 |
Unscented Transform (0) | 2010.06.12 |
이미지 프레임과 실제 패턴 상의 점을 1 대 1로 비교하여 연결한 16쌍의 대응점 |
구한 카메라 파라미터를 가지고 실제 패턴 위의 점들을 이미지 프레임에 reproject한 결과 (보라색 점)와 실제 패턴의 좌표를 기준으로 한 그래픽이 이미지 프레임 상에 어떻게 나타나는지 그린 결과 (노란색 상자) |
virtual studio 구현: camera calibration (0) | 2010.05.26 |
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Jonathan Merritt's Camera Calibration for Blender (0) | 2010.05.18 |
virtual studio 구현: feature points matching test (0) | 2010.05.14 |
Rahbar, K. & Pourreza, H. R "Inside looking out camera pose estimation for virtual studio" (0) | 2010.04.28 |
virtual studio 구현: pattern design (0) | 2010.04.27 |
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Seong-Woo Park, Yongduek Seo and Ki-Sang Hong1
In this paper, we present an overall algorithm for real-time camera parameter extraction, which is one of the key elements in implementing virtual studio, and we also present a new method for calculating the lens distortion parameter in real time. In a virtual studio, the motion of a virtual camera generating a graphic studio must follow the motion of the real camera in order to generate a realistic video product. This requires the calculation of camera parameters in real-time by analyzing the positions of feature points in the input video. Towards this goal, we first design a special calibration pattern utilizing the concept of cross-ratio, which makes it easy to extract and identify feature points, so that we can calculate the camera parameters from the visible portion of the pattern in real-time. It is important to consider the lens distortion when zoom lenses are used because it causes nonnegligible errors in the computation of the camera parameters. However, the Tsai algorithm, adopted for camera calibration, calculates the lens distortion through nonlinear optimization in triple parameter space, which is inappropriate for our real-time system. Thus, we propose a new linear method by calculating the lens distortion parameter independently, which can be computed fast enough for our real-time application. We implement the whole algorithm using a Pentium PC and Matrox Genesis boards with five processing nodes in order to obtain the processing rate of 30 frames per second, which is the minimum requirement for TV broadcasting. Experimental results show this system can be used practically for realizing a virtual studio.
generating virtual studio
영상에서 찾아진 특징점을 자동으로 인식하기 위해서는 공간 상의 점들과 영상에 나타난 그것들의 대응점에 대해서 같은 값을 갖는 성질이 필요한데 이것을 기하적 불변량 (Geometric Invariant)이라고 한다. 본 연구에서는 여러 불변량 가운데 cross-ratio를 이용하여 패턴을 제작하고, 영상에서 불변량의 성질을 이용하여 패턴을 자동으로 찾고 인식할 수 있게 하는 방법을 제안한다.
카메라의 움직임을 알아내기 위해서는 공간상에 인식이 가능한 물체가 있어야 한다. 즉, 어느 위치에서 보더라도 영상에 나타난 특징점을 찾을 수 있고, 공간상의 어느 점에 대응되는 점인지를 알 수 있어야 한다.
패턴이 인식 가능하기 위해서는 카메라가 어느 위치, 어느 자세로 보던지 항상 같은 값을 갖는 기하적 불변량 (Geometric Invariant)이 필요하다.
R1x = 0
이상적인 렌즈의 optical axis가 영상면에 수직이고 변하지 않는다고 할 때, 영상 중심은 카메라의 줌 동작 동안 고정된 값으로 계산된다. (그러나 실제 렌즈의 불완전한 특성 때문에 카메라의 줌 동작 동안 영상 중심 역시 변하게 되는데, 이 변화량은 적용 범위 이내에서 2픽셀 이하이다. 따라서 본 연구에서는 이러한 변화를 무시하고 이상적인 렌즈를 가정하여 줌동작에 의한 영상 중심을 구하게 된다.)
For zoom lenses, the image centers vary as the camera zooms because the zooming operation is executed by a composite combination of several lenses. However, when we examined the location of the image centers, its standard deviation was about 2 pixels; thus we ignored the effect of the image center change.
Zoom lenses are zoomed by a complicated combination of several lenses so that the effective focal length and distortion coefficient vary during zooming operations.
When using the coplanar pattern with small depth variation, it turns out that focal length and z-translation cannot be separated exactly and reliably even with small noise.
카메라 변수 추출에 있어서 공간상의 특징점들이 모두 하나의 평면상에 존재할 때는 초점거리와 z 방향으로의 이동이 상호 연관 (coupling)되어 계산값의 안정성이 결여되기 쉽다.
Collinearity represents a property when the line in the world coordinate is also shown as a line in the image. This property is not preserved when the lens has a distortion.
Once the lens distortion is calculated, we can execute camera calibration using linear methods.
가상 스튜디오 구현에 있어서는 시간 지연이 항상 같은 값을 가지게 하는 것이 필수적이므로, 실제 적용에서는 예측 (prediction)이 들어가는 필터링 방법(예를 들면, Kalman filter)은 사용할 수가 없었다.
photometric stereo 09-07-03 (0) | 2009.07.06 |
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GO MC PS references (0) | 2009.07.03 |
Linear Least Squares (0) | 2009.07.03 |
Reinhard Diestel <Graph Theory> (0) | 2009.06.16 |
photometric stereo 2009-06-10 (0) | 2009.06.10 |
RoSEC 2010 winter school (0) | 2010.01.14 |
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CUDA (0) | 2009.04.24 |
음악의 경계를 넘다: (3) 음악과 소리, 그 경계의 애매함 (0) | 2008.05.11 |
Stephen Lin "Seeing the World as It Really is" (0) | 2008.05.07 |
라울 자무디오 강연 (0) | 2008.03.29 |
A tutorial on particle filters for online nonlinear/non-Gaussian Bayesian tracking
Arulampalam, M.S. Maskell, S. Gordon, N. Clapp, T.
Defence Sci. & Technol. Organ., Adelaide, SA , Australia;
sedumi
Kolman & Beck, Ch.1 Eg.1
: Activity Analysis or Product Mix
>> c = [-120; -100; 0; 0];
>> A = [ 2, 2, 1, 0; 5, 3, 0, 1];
>> b = [8, 15];
>> x= sedumi(A,b,c)
SeDuMi 1.1R3 by AdvOL, 2006 and Jos F. Sturm, 1998-2003.
Alg = 2: xz-corrector, Adaptive Step-Differentiation, theta = 0.250, beta = 0.500
eqs m = 2, order n = 5, dim = 5, blocks = 1
nnz(A) = 6 + 0, nnz(ADA) = 4, nnz(L) = 3
it : b*y gap delta rate t/tP* t/tD* feas cg cg prec
0 : 4.18E-002 0.000
1 : -5.02E+002 1.25E-002 0.000 0.2989 0.9000 0.9000 1.77 1 1 3.8E+000
2 : -4.29E+002 3.65E-003 0.000 0.2927 0.9000 0.9000 2.52 1 1 6.4E-001
3 : -4.29E+002 2.84E-004 0.000 0.0778 0.9900 0.9900 1.19 1 1 4.5E-002
4 : -4.30E+002 9.99E-007 0.000 0.0035 0.9990 0.9990 1.03 1 1
iter seconds digits c*x b*y
4 0.2 Inf -4.3000000000e+002 -4.3000000000e+002
|Ax-b| = 2.3e-015, [Ay-c]_+ = 0.0E+000, |x|= 2.9e+000, |y|= 3.6e+001
Detailed timing (sec)
Pre IPM Post
3.125E-002 1.563E-001 0.000E+000
Max-norms: ||b||=15, ||c|| = 120,
Cholesky |add|=0, |skip| = 0, ||L.L|| = 2.11427.
x =
(1,1) 1.5000
(2,1) 2.5000
>>
>> c = [5; 7; 9; 6; 7; 10; 0; 0; 0; 0; 0];
>> A = [1,1,1,0,0,0,1,0,0,0,0; 0,0,0,1,1,1,0,1,0,0,0; 1,0,0,1,0,0,0,0,-1,0,0; 0,1,0,0,1,0,0,0,0,-1,0; 0,0,1,0,0,1,0,0,0,0,-1];
>> b = [120; 140; 100; 60; 80];
>> x = sedumi(A,b,c)
SeDuMi 1.1R3 by AdvOL, 2006 and Jos F. Sturm, 1998-2003.
Alg = 2: xz-corrector, Adaptive Step-Differentiation, theta = 0.250, beta = 0.500
eqs m = 5, order n = 12, dim = 12, blocks = 1
nnz(A) = 17 + 0, nnz(ADA) = 17, nnz(L) = 12
it : b*y gap delta rate t/tP* t/tD* feas cg cg prec
0 : 3.24E+003 0.000
1 : 1.16E+003 9.69E+002 0.000 0.2991 0.9000 0.9000 2.37 1 1 1.6E+000
2 : 1.63E+003 2.05E+002 0.000 0.2114 0.9000 0.9000 1.34 1 1 3.0E-001
3 : 1.69E+003 3.84E+001 0.000 0.1875 0.9000 0.9000 1.20 1 1 5.1E-002
4 : 1.70E+003 1.08E+000 0.000 0.0282 0.9900 0.9900 1.03 1 1
iter seconds digits c*x b*y
4 0.5 15.9 1.7000000000e+003 1.7000000000e+003
|Ax-b| = 5.6e-014, [Ay-c]_+ = 7.6E-016, |x|= 1.1e+002, |y|= 1.4e+001
Detailed timing (sec)
Pre IPM Post
3.125E-001 4.531E-001 1.250E-001
Max-norms: ||b||=140, ||c|| = 10,
Cholesky |add|=0, |skip| = 0, ||L.L|| = 1.
x =
(1,1) 68.6083
(3,1) 51.3917
(4,1) 31.3917
(5,1) 60.0000
(6,1) 28.6083
(8,1) 20.0000
SeDuMi (0) | 2009.03.11 |
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[Kolman & Beck] Chapter 1 Introduction to Linear Programming (0) | 2009.03.11 |
Kolman & Beck <Elementary linear programming with applications> 2nd ed. (0) | 2009.03.09 |
[Boyd & Vandenberghe] Chapter 4 Convex Optimization Problems (0) | 2009.03.04 |
[Boyd & Vandenberghe] Chapter 3 Convex Functions (0) | 2009.02.23 |
Homework #1 (0) | 2009.03.11 |
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[Kolman & Beck] Chapter 1 Introduction to Linear Programming (0) | 2009.03.11 |
Kolman & Beck <Elementary linear programming with applications> 2nd ed. (0) | 2009.03.09 |
[Boyd & Vandenberghe] Chapter 4 Convex Optimization Problems (0) | 2009.03.04 |
[Boyd & Vandenberghe] Chapter 3 Convex Functions (0) | 2009.02.23 |
http://en.wikipedia.org/wiki/Linear_programming
1.1 The Linear Programming Problem
general linear programming problem
- objective function
- constraints
standard form
canonical form
Every linear programming problem that has unconstrained variables can be solved by solving a corresponding linear programming problem in which all the variables are constrained to be nonnegative.
Every linear programming problem can be formulated as a corresponding standard linear programming problem or as a corresponding canonical linear programming problem. (53p)
Homework #1 (0) | 2009.03.11 |
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SeDuMi (0) | 2009.03.11 |
Kolman & Beck <Elementary linear programming with applications> 2nd ed. (0) | 2009.03.09 |
[Boyd & Vandenberghe] Chapter 4 Convex Optimization Problems (0) | 2009.03.04 |
[Boyd & Vandenberghe] Chapter 3 Convex Functions (0) | 2009.02.23 |
Operations research (OR) is a scientific method for providing a quantitative basis for decision making (that can be used in almost any field of endeavor).
The techniques of OR give a logical and systematic way of formulating a problem so that the tools of mathematics can be applied to find a solution (when the established way of doing things can be improved.
A central problem in OR is the optimal allocation of scarce resources (including raw materials, labor, capital, energy, and processing time).
eg. T. C. Koopmans and L. V. Kantorovich, the 1975 Nobel Prize awardees
There are two types of mathematical models: deterministic and probabilistic.
A deterministic model will always yield the same set of output values for a given set of input values, whereas a probabilistic model will typically yield many different sets of output values according to some probability distribution.
SeDuMi (0) | 2009.03.11 |
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[Kolman & Beck] Chapter 1 Introduction to Linear Programming (0) | 2009.03.11 |
[Boyd & Vandenberghe] Chapter 4 Convex Optimization Problems (0) | 2009.03.04 |
[Boyd & Vandenberghe] Chapter 3 Convex Functions (0) | 2009.02.23 |
[Boyd & Vandenberghe] Chapter 2 Convex Sets (0) | 2009.02.23 |
ezplot('x*log(x)')
http://en.wikipedia.org/wiki/Slack_variable
4.2 Convex Optimization
4.3 Linear Optimization Problems
http://en.wikipedia.org/wiki/Linear_program
4.4 Quadratic Optimization Problems
http://en.wikipedia.org/wiki/Quadratic_program
Markowitz portfolio optimization
4.4.2 Second-order cone programming
http://en.wikipedia.org/wiki/SOCP
http://en.wikipedia.org/wiki/Minimal_surface
[Kolman & Beck] Chapter 1 Introduction to Linear Programming (0) | 2009.03.11 |
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Kolman & Beck <Elementary linear programming with applications> 2nd ed. (0) | 2009.03.09 |
[Boyd & Vandenberghe] Chapter 3 Convex Functions (0) | 2009.02.23 |
[Boyd & Vandenberghe] Chapter 2 Convex Sets (0) | 2009.02.23 |
[Boyd & Vandenberghe] Chapter 1 Introduction (0) | 2009.02.19 |
[Boyd & Vandenberghe] Chapter 2 Convex Sets (0) | 2009.02.23 |
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[Boyd & Vandenberghe] Chapter 1 Introduction (0) | 2009.02.19 |
[Boyd & Vandenberghe] Appendix C: Numerical linear algebra background (0) | 2009.02.02 |
[Boyd & Vandenberghe] Appendix B: Problems involving two quadratic functions (0) | 2009.01.22 |
[Boyd & Vandenberghe] Appendix A: Mathematical background (0) | 2009.01.09 |