A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images
The shadow statistical method (SSM) used for extracting the significant wave height (SWH) from X-band marine radar images was further investigated because of its advantage of not requiring an external reference for calibration. Currently, a fixed shadow segmentation threshold is utilized to extract...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-11-01
|
| Series: | Remote Sensing |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-4292/15/22/5355 |
| _version_ | 1797457862542229504 |
|---|---|
| author | Yanbo Wei Yujie Wang Chendi He Huili Song Zhizhong Lu Hui Wang |
| author_facet | Yanbo Wei Yujie Wang Chendi He Huili Song Zhizhong Lu Hui Wang |
| author_sort | Yanbo Wei |
| collection | DOAJ |
| description | The shadow statistical method (SSM) used for extracting the significant wave height (SWH) from X-band marine radar images was further investigated because of its advantage of not requiring an external reference for calibration. Currently, a fixed shadow segmentation threshold is utilized to extract the SWH from a radar image based on the SSM. However, the retrieval accuracy of the SWH is not ideal for low wind speeds since the echo intensity of sea waves rapidly decays over distance. In order to solve this problem, an adaptive shadow threshold, which varies with echo intensity over distance and can accurately divide the radar image into shadow and nonshadow areas, is adopted to calculate the wave slope (WS) based on the texture feature of the edge image. Instead of using the averaged WS, the wave slope feature vector (WSFV) is constructed for retrieving the SWH since the illumination ratio and the calculated WS in the azimuth are different for shore-based radar images. In this paper, the SWH is calculated based on the constructed WSFV and classical support vector regression (SVR) technology. The collected 222 sets of X-band marine radar images with an SWH range of 1.0∼3.5 m and an average wind speed range of 5∼10 m/s were utilized to verify the performance of the proposed approach. The buoy record, which was deployed during the experiment, was used as the ground truth. For the proposed approach, the mean bias (BIAS) and the mean absolute error (MAE) were 0.03 m and 0.14 m when the ratio of the training set to the test set was 1:1. Compared to the traditional SSM, the correlation coefficient (CC) of the proposed approach increased by 0.27, and the root mean square error (RMSE) decreased by 0.28 m. |
| first_indexed | 2024-03-09T16:29:48Z |
| format | Article |
| id | doaj.art-d4401b30031440ae854933f5ee1350e5 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T16:29:48Z |
| publishDate | 2023-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-d4401b30031440ae854933f5ee1350e52023-11-24T15:04:34ZengMDPI AGRemote Sensing2072-42922023-11-011522535510.3390/rs15225355A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar ImagesYanbo Wei0Yujie Wang1Chendi He2Huili Song3Zhizhong Lu4Hui Wang5College of Physics and Electronic Information, Luoyang Normal University, No. 6 Jiqing Road, Luoyang 471934, ChinaCollege of Physics and Electronic Information, Luoyang Normal University, No. 6 Jiqing Road, Luoyang 471934, ChinaState Key Laboratory of Digital Multimedia Technology, Hisense Co., Ltd., No. 399 Songling Street, Qingdao 266000, ChinaCollege of Intelligent Systems Science and Engineering, Harbin Engineering University, No. 145 Nantong Street, Harbin 150001, ChinaCollege of Intelligent Systems Science and Engineering, Harbin Engineering University, No. 145 Nantong Street, Harbin 150001, ChinaSchool of Naval Architecture and Ocean Engineering, Guangzhou Maritime University, No. 101 Hongshan 3rd Road, Guangzhou 510725, ChinaThe shadow statistical method (SSM) used for extracting the significant wave height (SWH) from X-band marine radar images was further investigated because of its advantage of not requiring an external reference for calibration. Currently, a fixed shadow segmentation threshold is utilized to extract the SWH from a radar image based on the SSM. However, the retrieval accuracy of the SWH is not ideal for low wind speeds since the echo intensity of sea waves rapidly decays over distance. In order to solve this problem, an adaptive shadow threshold, which varies with echo intensity over distance and can accurately divide the radar image into shadow and nonshadow areas, is adopted to calculate the wave slope (WS) based on the texture feature of the edge image. Instead of using the averaged WS, the wave slope feature vector (WSFV) is constructed for retrieving the SWH since the illumination ratio and the calculated WS in the azimuth are different for shore-based radar images. In this paper, the SWH is calculated based on the constructed WSFV and classical support vector regression (SVR) technology. The collected 222 sets of X-band marine radar images with an SWH range of 1.0∼3.5 m and an average wind speed range of 5∼10 m/s were utilized to verify the performance of the proposed approach. The buoy record, which was deployed during the experiment, was used as the ground truth. For the proposed approach, the mean bias (BIAS) and the mean absolute error (MAE) were 0.03 m and 0.14 m when the ratio of the training set to the test set was 1:1. Compared to the traditional SSM, the correlation coefficient (CC) of the proposed approach increased by 0.27, and the root mean square error (RMSE) decreased by 0.28 m.https://www.mdpi.com/2072-4292/15/22/5355adaptive shadow segmentation thresholdmarine radar imagessignificant wave height (SWH)wave slope feature vector (WSFV) |
| spellingShingle | Yanbo Wei Yujie Wang Chendi He Huili Song Zhizhong Lu Hui Wang A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images Remote Sensing adaptive shadow segmentation threshold marine radar images significant wave height (SWH) wave slope feature vector (WSFV) |
| title | A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images |
| title_full | A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images |
| title_fullStr | A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images |
| title_full_unstemmed | A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images |
| title_short | A Method of Extracting the SWH Based on a Constituted Wave Slope Feature Vector (WSFV) from X-Band Marine Radar Images |
| title_sort | method of extracting the swh based on a constituted wave slope feature vector wsfv from x band marine radar images |
| topic | adaptive shadow segmentation threshold marine radar images significant wave height (SWH) wave slope feature vector (WSFV) |
| url | https://www.mdpi.com/2072-4292/15/22/5355 |
| work_keys_str_mv | AT yanbowei amethodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT yujiewang amethodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT chendihe amethodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT huilisong amethodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT zhizhonglu amethodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT huiwang amethodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT yanbowei methodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT yujiewang methodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT chendihe methodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT huilisong methodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT zhizhonglu methodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages AT huiwang methodofextractingtheswhbasedonaconstitutedwaveslopefeaturevectorwsfvfromxbandmarineradarimages |