Journal of Korea Multimedia Society (한국멀티미디어학회논문지)

Korea Multimedia Society (한국멀티미디어학회)
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Depth Measurement Method Robust against Scattering of Line Lasers

라인 레이저의 산란에 강인한 심도 측정 방법

  • Ko, Kwangjin (Department of Electrical Information Control Engineering, Hongik Univ.) ;
  • Yeon, Sungho (Department of Electrical Information Control Engineering, Hongik Univ.) ;
  • Kim, Jaemin (School of Electronic and Electrical Engineering, Hongik Univ.)
  • Received : 2018.01.10
  • Accepted : 2018.02.20
  • Published : 2018.02.28
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Abstract

Line-laser beams are used for depth measurement of welding beads along the circumference of a pipe. For this, first we project a line-laser beam on an rotating pipe and take a sequence of images of the beam projected on the pipe using a CCD camera. Second, the projected line laser beam in each image is detected, converted into a thin curve. Finally measure the distance between the thinned curve and an imaginary line. When a line-laser beam is projected to a rough metal surface such as arc welding beads, the beam is severely scattered. This severe scattering makes the thinned curve perturbed. In this paper, we propose a thinning method robust against scattering of line lasers. First, we extract a projected line laser beam region using an adaptive threshold. Second, we model a thinned curve with a spline curve with control points. Next, we adjust the control points to fit the curve to the projected line-laser beam. Finally, we take a weighted mean of thin curves on a sequence of image frames. Experiments shows that the proposed thinning method results in a thinning curve, which is smooth and fit to the projected line-laser beam with small error.

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References

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