Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method
In this study, a method based on the discrete wavelet transform (DWT) and azimuth-scale expansion is presented to retrieve the sea-surface wind direction from a single X-band marine radar image. The algorithm first distinguishes rain-free and rain-contaminated radar images based on the occlusion zer...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-05-01
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| Series: | Entropy |
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| Online Access: | https://www.mdpi.com/1099-4300/24/6/747 |
| _version_ | 1797487716578885632 |
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| author | Huanyu Yu Hui Wang Zhizhong Lu |
| author_facet | Huanyu Yu Hui Wang Zhizhong Lu |
| author_sort | Huanyu Yu |
| collection | DOAJ |
| description | In this study, a method based on the discrete wavelet transform (DWT) and azimuth-scale expansion is presented to retrieve the sea-surface wind direction from a single X-band marine radar image. The algorithm first distinguishes rain-free and rain-contaminated radar images based on the occlusion zero-pixel percentage and then discards the rain-contaminated images. The radar image whose occlusion areas have been removed is decomposed into different low-frequency sub-images by the 2D DWT, and the appropriate low-frequency sub-image is selected. Images collected with a standard marine HH-polarized X-band radar operating at grazing incidence display a single intensity peak in the upwind direction. To overcome the influence of the occlusion area, before determining the wind direction, the data near the ship bow are shifted to expand the azimuth scale of the data. Finally, a harmonic function is least-square-fitted to the range-averaged radar return of the low-frequency sub-image as a function of the antenna look azimuth to determine the wind direction. Different from the wind-direction retrieval algorithms previously presented, this method is more suitable for sailing ships, as it functions well even if the radar data are heavily blocked. The results show that compared with the single-curve fitting algorithm, the algorithm based on DWT and azimuth-scale expansion can improve the wind-direction results in sailing ships, showing a reduction of 7.84° in the root-mean-square error with respect to the reference. |
| first_indexed | 2024-03-09T23:51:43Z |
| format | Article |
| id | doaj.art-8a90f39573744ffc90dd760f496892d7 |
| institution | Directory Open Access Journal |
| issn | 1099-4300 |
| language | English |
| last_indexed | 2024-03-09T23:51:43Z |
| publishDate | 2022-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Entropy |
| spelling | doaj.art-8a90f39573744ffc90dd760f496892d72023-11-23T16:32:29ZengMDPI AGEntropy1099-43002022-05-0124674710.3390/e24060747Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion MethodHuanyu Yu0Hui Wang1Zhizhong Lu2College of Intelligent Systems Science and Engineering, Harbin Engineering University, No. 145 Nantong Street, Harbin 150001, ChinaDepartment of Electronic Information, Jiangsu University of Science and Technology, Zhenjiang 212003, ChinaCollege of Intelligent Systems Science and Engineering, Harbin Engineering University, No. 145 Nantong Street, Harbin 150001, ChinaIn this study, a method based on the discrete wavelet transform (DWT) and azimuth-scale expansion is presented to retrieve the sea-surface wind direction from a single X-band marine radar image. The algorithm first distinguishes rain-free and rain-contaminated radar images based on the occlusion zero-pixel percentage and then discards the rain-contaminated images. The radar image whose occlusion areas have been removed is decomposed into different low-frequency sub-images by the 2D DWT, and the appropriate low-frequency sub-image is selected. Images collected with a standard marine HH-polarized X-band radar operating at grazing incidence display a single intensity peak in the upwind direction. To overcome the influence of the occlusion area, before determining the wind direction, the data near the ship bow are shifted to expand the azimuth scale of the data. Finally, a harmonic function is least-square-fitted to the range-averaged radar return of the low-frequency sub-image as a function of the antenna look azimuth to determine the wind direction. Different from the wind-direction retrieval algorithms previously presented, this method is more suitable for sailing ships, as it functions well even if the radar data are heavily blocked. The results show that compared with the single-curve fitting algorithm, the algorithm based on DWT and azimuth-scale expansion can improve the wind-direction results in sailing ships, showing a reduction of 7.84° in the root-mean-square error with respect to the reference.https://www.mdpi.com/1099-4300/24/6/747discrete wavelet transform (DWT)azimuth-scale expansionoccluded imageX-band marine radarwind direction |
| spellingShingle | Huanyu Yu Hui Wang Zhizhong Lu Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method Entropy discrete wavelet transform (DWT) azimuth-scale expansion occluded image X-band marine radar wind direction |
| title | Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method |
| title_full | Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method |
| title_fullStr | Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method |
| title_full_unstemmed | Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method |
| title_short | Wind-Direction Estimation from Single X-Band Marine Radar Image Improvement by Utilizing the DWT and Azimuth-Scale Expansion Method |
| title_sort | wind direction estimation from single x band marine radar image improvement by utilizing the dwt and azimuth scale expansion method |
| topic | discrete wavelet transform (DWT) azimuth-scale expansion occluded image X-band marine radar wind direction |
| url | https://www.mdpi.com/1099-4300/24/6/747 |
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