problem def find straight lines images from

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Unformatted text preview: in y- direc-on }༇  Gradient Magnitude }༇  M= }༇  2 x f +f 2 y Gradient Direc-on θ = arctan fy fx Detection Stage - Threshold }༇  Gradient Magnitude }༇  Gradient Magnitude normalized b/w 0- 100 }༇  Applica-on of a threshold Gradient Magnitude Log of M to enhance visibility T = 10 T = 20 T = 40 T = 80 What about Gradient Direction? }༇  }༇  }༇  }༇  Gradient Direc-on is always perpendicular to edge Direc-on of most change of gray levels Thick edges can be eliminated using gradient direc-on Weak edges also captured in this manner Line Detection Using Edge Representation… }༇  }༇  Stereo matching problem Input: }༇  }༇  }༇  Computa-on }༇  }༇  Find corresponding features in two images Output }༇  }༇  Two images with disparity Camera Calibra-on informa-on Disparity in corresponding features is related to depth Edges and corners help in finding correspondences Finding Shapes from Edges Finding Shapes from Edges Edge Representation for Shape Analysis }༇  What about noisy edges? }༇  Problem Def.: Find straight lines… Images from: http://www.cogs.susx.ac.uk/users/davidy/teachvision/vision4.html Problems in Finding Lines Missing Data Noisy Data Mul-ple Lines Parameter Optimization: Least Squared Error Solutions }༇  Ficng a line to a set of data points… x y 1.3 5.7 2.4 7.3 3.4 10.5 4.6 11.8 5.3 13.9 6.6 16.3 6.4 15.3 8.0 17.9 8.9 20.8 9.2 20.9 }༇  Equa-on of best fit line ? Line Fitting: Least Squared Error Solution }༇  Step 1: Iden-fy the model }༇  }༇  Step 2: Set up an error term which will give the goodness of every point with respect to the (unknown) m...
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