Extraction of Gravel Size Information from Deblurred Through Water Image

• Main Authors: Wei-ShenLo, 羅維伸
• Other Authors: Chi-Kuei Wang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/75600921501348570776

碩士 === 國立成功大學 === 測量及空間資訊學系碩博士班 === 100 === Underwater photography is useful for gathering physical information of the instream environment. Due to the wave actions at the water surface, taking high quality pictures in shallow water area (〈 40 cm) is difficult. In addition, the use of underwater camera is impossible such environment. In this thesis, a method of applying two Richardson-Lucy iterations performance on long-exposure through water image, which is constructed from continues photographs by mean-based filter, is proposed. The red point target with known physical size is placed on the river bottom at the time of image acquisition in order to obtain the combined point spread function due to the surface wave action and water media. Finally, a deblurred image is produced by an iterative scheme of Lucy-Richardson algorithm. The proposed method is effective for correcting the picture of underwater gravels in shallow water that are distorted by waves, and the particle size distribution can be calculated from the deblurred image to derive the gravel size information. The comparison between the result of mean-based filter image(blurred image), mode-based filter image, and deblurred image is conducted. The result shows that the image quality and the particle size distribution of deblurred image is better, and the deblurred image is effective in deriving the underwater gravel.