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Applied Optics

Applied Optics


  • Editor: James C. Wyant
  • Vol. 45, Iss. 12 — Apr. 20, 2006
  • pp: 2672–2688

Use of thresholding algorithms in the processing of raindrop imagery

D. D. Saxena and J. R. Saylor  »View Author Affiliations

Applied Optics, Vol. 45, Issue 12, pp. 2672-2688 (2006)

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Several thresholding algorithms are applied to the analysis of drop images, and their performance is compared. Images were obtained by use of a digital camera setup in which drops were illuminated from behind, resulting in an image of the drop silhouette. Each algorithm was evaluated based on the accuracy of the drop diameter obtained from the thresholded image and on the size of the depth of field. Because of the difficulty associated with creating drops that have a known diameter, solid spheres composed of a glass with an index of refraction close to that of water were used in computing the depth of field and in determining the accuracy of measured diameter. The application of this study is to the automatic measurement of raindrops and images were obtained during several storms. With each thresholding algorithm this raindrop imagery was used to compute the probability density function of drop diameter, and the rain rate. The performance of each thresholding algorithm was quantified by comparison of these measurements with simultaneous measurements obtained by use of a Joss–Waldvogel disdrometer.

© 2006 Optical Society of America

OCIS Codes
(010.3920) Atmospheric and oceanic optics : Meteorology
(100.0100) Image processing : Image processing
(100.2000) Image processing : Digital image processing

Original Manuscript: June 24, 2005
Revised Manuscript: October 31, 2005
Manuscript Accepted: November 2, 2005

D. D. Saxena and J. R. Saylor, "Use of thresholding algorithms in the processing of raindrop imagery," Appl. Opt. 45, 2672-2688 (2006)

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