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Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †

Laser stripe center extraction is a key step for the profile measurement of line structured light sensors (LSLS). To accurately obtain the center coordinates at sub-pixel level, an improved gray-gravity method (IGGM) was proposed. Firstly, the center points of the stripe were computed using the gray...

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Detalles Bibliográficos
Autores principales: Li, Yuehua, Zhou, Jingbo, Huang, Fengshan, Liu, Lijian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5422175/
https://www.ncbi.nlm.nih.gov/pubmed/28394288
http://dx.doi.org/10.3390/s17040814
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author Li, Yuehua
Zhou, Jingbo
Huang, Fengshan
Liu, Lijian
author_facet Li, Yuehua
Zhou, Jingbo
Huang, Fengshan
Liu, Lijian
author_sort Li, Yuehua
collection PubMed
description Laser stripe center extraction is a key step for the profile measurement of line structured light sensors (LSLS). To accurately obtain the center coordinates at sub-pixel level, an improved gray-gravity method (IGGM) was proposed. Firstly, the center points of the stripe were computed using the gray-gravity method (GGM) for all columns of the image. By fitting these points using the moving least squares algorithm, the tangential vector, the normal vector and the radius of curvature can be robustly obtained. One rectangular region could be defined around each of the center points. Its two sides that are parallel to the tangential vector could alter their lengths according to the radius of the curvature. After that, the coordinate for each center point was recalculated within the rectangular region and in the direction of the normal vector. The center uncertainty was also analyzed based on the Monte Carlo method. The obtained experimental results indicate that the IGGM is suitable for both the smooth stripes and the ones with sharp corners. The high accuracy center points can be obtained at a relatively low computation cost. The measured results of the stairs and the screw surface further demonstrate the effectiveness of the method.
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spelling pubmed-54221752017-05-12 Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method † Li, Yuehua Zhou, Jingbo Huang, Fengshan Liu, Lijian Sensors (Basel) Article Laser stripe center extraction is a key step for the profile measurement of line structured light sensors (LSLS). To accurately obtain the center coordinates at sub-pixel level, an improved gray-gravity method (IGGM) was proposed. Firstly, the center points of the stripe were computed using the gray-gravity method (GGM) for all columns of the image. By fitting these points using the moving least squares algorithm, the tangential vector, the normal vector and the radius of curvature can be robustly obtained. One rectangular region could be defined around each of the center points. Its two sides that are parallel to the tangential vector could alter their lengths according to the radius of the curvature. After that, the coordinate for each center point was recalculated within the rectangular region and in the direction of the normal vector. The center uncertainty was also analyzed based on the Monte Carlo method. The obtained experimental results indicate that the IGGM is suitable for both the smooth stripes and the ones with sharp corners. The high accuracy center points can be obtained at a relatively low computation cost. The measured results of the stairs and the screw surface further demonstrate the effectiveness of the method. MDPI 2017-04-10 /pmc/articles/PMC5422175/ /pubmed/28394288 http://dx.doi.org/10.3390/s17040814 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Li, Yuehua
Zhou, Jingbo
Huang, Fengshan
Liu, Lijian
Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †
title Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †
title_full Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †
title_fullStr Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †
title_full_unstemmed Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †
title_short Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method †
title_sort sub-pixel extraction of laser stripe center using an improved gray-gravity method †
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5422175/
https://www.ncbi.nlm.nih.gov/pubmed/28394288
http://dx.doi.org/10.3390/s17040814
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