Transcript ITK Hough Transform

ITK Hough Transform
指導教授: 張顧耀
學生: 沈仁立
2015/4/13
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Outline
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Hough Transform
◦ Find line
◦ Find circle

ITK Hough Transform(Ch9.5)
◦ itk::HoughTransform2DLinesImageFilter
測試
 疑問
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ITK Hough Transform
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Hough Transform
-Find line
b
y
y=mx+b
(2,1)
y=x-1
2 = 3m+b
(3,2)
a
1 = 2m+b
x
影像空間 x-y
參數空間 a-b
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ITK Hough Transform
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Hough Transform
-Find line
影像空間 x-y
參數空間 a-b
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累加器
(Accumulator)
ITK Hough Transform
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Hough Transform
-Find circle
影像空間
參數空間
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ITK Hough Transform
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Hough Transform
-Find circle

http://www.markschulze.net/java/hough/
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ITK Hough Transform
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Hough Transform
-Find circle
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ITK Hough Transform
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ITK Hough Transform
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itk::HoughTransform2DLinesImageFilter
◦ Find straight lines in a 2-dimensional image
◦ Step
 Load image data
 itk::GradientMagnitudeImageFilter
 To segment edges
 Threshold
 Keep only bright values
 Only high values will be used
 Hough transform
 Number of lines
 Variance of the accumulator blurring
 Radius of the disk to remove from the accumulator
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測試
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Line:50 var:5 radius:10 Line:50 var:5 radius:5
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測試
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Line:50 var:5 radius:3
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測試
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Line:50 var:3 radius:10 Line:50 var:3 radius:5
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測試
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Line:50 var:3 radius:3
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測試
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Line:50 var:7 radius:10 Line:50 var:7 radius:5
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測試
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Line:50 var:7 radius:3
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疑問
整張影像 or 部份區域
 結果的反推
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