完整后设资料纪录
DC 栏位 | 值 | 语言 |
---|---|---|
dc.contributor.author | 郑义霖 | en_US |
dc.contributor.author | Cheng, Yi-Lin | en_US |
dc.contributor.author | 张宪国 | en_US |
dc.contributor.author | Chang, Hsien-Kuo | en_US |
dc.date.accessioned | 2014-12-12T02:44:01Z | - |
dc.date.available | 2014-12-12T02:44:01Z | - |
dc.date.issued | 2013 | en_US |
dc.identifier.uri | http://140.113.39.130/cdrfb3/record/nctu/#GT070151250 | en_US |
dc.identifier.uri | http://hdl.handle.net/11536/75751 | - |
dc.description.abstract | 以船舶上的单束或多束声纳来测量海域地形水深的传统方法,需要高成本、精密仪器设备及大量人力等缺点;卫星影像具有全面性及多资讯等优点,已被广泛运用于各领域之研究,亦被本文引用来推估波长及海下的水深。本研究主要应用二维经验模态分解方法分解卫星影像,撷取杂讯较少的波浪分解影像,再运行二维快速傅立叶转换方法获得空间频谱,以决定卫星影像图中波向及波长。由切割小影像所决定的波向,连续地推进切割小影像直至近岸,即可获得波向线;若以卫星影像求得的波长及周期代入线性波浪理论的频散关系式则可推估水深。 本研究选定宜兰头城海岸及屏东县枋寮渔港海域两处当为验证本研究方法可行的基地。由本方法推算卫星影像的头城海岸的波浪周期与实测值及模式计算之误差仅为0.14秒与0.54秒,显示本方法推算波长的正确性。另外本研究选择头城海岸8个剖面,检验本法所得在水深-6m至-12m的修正水深与实测值的均方根误差的平均值为0.84m,而在枋寮海域的均方根误差的平均值为1.23m。本文以理论评估出卫星影像的空间解析度会产生本法推估水深有约1m的误差。在未来卫星影像的空间解析度提高下,本文方法可提供更精准的海域地形水深,就具有工程可行性。 | zh_TW |
dc.description.abstract | Bathymetric estimation was traditionally obtained using single/multi-beam echo sounder on boats. However, taking time-consuming, requiring high cost and precise surveying instruments are disadvantages of bathymetric surveying. In recent years, satellite images that provide multi-information of large area have been commonly used in a wide range of researches, including the investigation on wave-length and wave directions. Those sub-images from one original satellite image are decomposed by bi-dimensional empirical mode decomposition (BEMD) and fast Fourier transform (FFT), to get spatial spectra where peak indicates the wave number and direction of primary waves. The track of wave directions from a sequence of sub-images forms a wave ray. The local water depth can be derived using dispersion relation of the linear wave theory from estimated wave-length and period of a sub-image. The Fangliao coast of Pingtung county and the Toucheng coast of northern Ilan county are chosen for examining the accuracy of the proposed method by the root mean squared error between the measured and calculated water depths. Eight selected beach profiles are chosen to have a mean RMSE of 0.84m for the Fangliao coast using corrected wavelengths and a mean RMSE of 1.23m for the Toucheng coast using originally obtained wavelengths. It is proven that 2-m spatial resolution of chosen satellite images can produce an error of about 1 m in depth estimation using the proposed method. When the spatial resolution of satellite images is promoted someday, the proposed method can offer concise bathymetry and is applicable for coastal planning. | en_US |
dc.language.iso | zh_TW | en_US |
dc.subject | 二维经验模态分解 | zh_TW |
dc.subject | 水深估算 | zh_TW |
dc.subject | 卫星影像 | zh_TW |
dc.subject | BEMD | en_US |
dc.subject | bathymetry estimation | en_US |
dc.subject | satellite image | en_US |
dc.title | 应用二维经验模态分解及快速傅立叶转换 于卫星影像推算海域地形之研究 | zh_TW |
dc.title | Bathymetric estimation from satellite images using BEMD and FFT | en_US |
dc.type | Thesis | en_US |
dc.contributor.department | 土木工程系所 | zh_TW |
显示于类别: | Thesis |