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Part II Plane Equation and Epipolar Geometry
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Duality
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Grassman Coordinates
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Points on the Same line and... By Duality,
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Points and Planes in 3D
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Points and Planes in 3D(Cont’d) For a Fourth point lying on the plane,
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Linear Transformation Transformation Group Linear Transformation Classification Euclidean Transformation, Affine Transformation, Projective Transformation
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Rigid Motions - Euclidean Trans... Using Homogeneous Coordinates, Action of the euclidean group on five points
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As a Subgroup.. And, Inverse is also possible for a following suitable matrix R -1.. Transformation Group For a Euclidean Group,
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Affine Transformations Action of the affine group on five points Parallel lines are preseved. R is Replaced by a general non-singular transformation matrix A
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General Linear Transformations It preserves the collinearity of points. For general non-singular linear transformations T, We get general linear or projective group of transformations. Action of the projective group on five points
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Projection From 3D to 2D Pin-hole camera model
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The Projection Equation
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The Projection Equation(Cont’d)
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Matrix Decomposition
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Internal & External parameters Internal orientation parameters External orientation parameters A Internal camera parameters R Camera rotation P 0 Camera position(projection point) :
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Tsai’s Camera Model Ow yw xw zw z,Z P(x,y,z) =P(xw,yw,zw) O y x Y XO1 Pu(Xu,Yu) Pd(Xd,Yd)
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Tsai’s Camera Model(Cont’d) Step 1 Step 2 Step 3 Step 4, f : focal length (xw,yw,zw) 3D world coordinate (x,y,z) 3D camera coordinate system (Xu,Yu) Ideal undistorted image coordinate (Xd,Yd) Distorted Image coordinate (Xf,Yf) Computer image coordinate in frame memory
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Determining the Parameters x 0,y 0 : The Origin of the normalized image system x, x : Scaling factor from the normalized image coordinates to the original : The deviation in the normalized system
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Summary of Camera Calibration Definition The process of determining internal and external parameters Determine in the following way 1) Find the 11 parameters of the projection matrix P using at least 6 known points in space 2) Find the unique factorization. This gives the internal parameters of the matrix A and the external parameters of the camera rotation and position
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Mapping from a Planar Surface
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Epipolar Geometry
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※ This constraint relation is known as the epipolar constraints The Fundamental Matrix
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Epipolar points, lines and planes : Epipolar line U B0B0 BeBe B A AeAe A0A0 평면 UA 0 B 0 : Epipolar plane A e,B e : Epipolar point Since,
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Computing the Fundamental matrix Given 8 points we can in general compute the F-matrix using just linear equations However, if we use the non-linear singularity constraint, [F]=0, we need only 7 points at the price of a more complicated algorithm
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Calibrated Cameras If we use the first camera as the reference frame, we have 계속
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Essential Matrix E is called the essential matrix
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