在处理分析海岸水陆特征时,引入水平集理论对复杂边界纹理特征信息进行提取。首先,对海岸线边界提取的相关研究及水平集理论进行了分析总结;然后,结合区域边界信息及其区域光滑非参数密度估计,引入海岸边界区域特征分割算法,利用多种类...在处理分析海岸水陆特征时,引入水平集理论对复杂边界纹理特征信息进行提取。首先,对海岸线边界提取的相关研究及水平集理论进行了分析总结;然后,结合区域边界信息及其区域光滑非参数密度估计,引入海岸边界区域特征分割算法,利用多种类型的影像对该算法进行了验证;最后,为了说明水平集算法(level set method,LSM)对提取海岸线特征信息的有效性,对LSM算法与梯度下降方法在海岸线特征提取上的效率差异进行了比较。结果表明:LSM对海岸特征复杂纹理和噪声等信息具有一定的鲁棒性,同时对于有效边缘信息具有较强的检测灵敏度,能够迅速、有效地对其边界信息进行特征提取。展开更多
The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater top...The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater topography, the wave environment in the offshore area is complex; beach types and sediment transport characteristics vary along different coasts. The coastlines extracted from six aerial photographs in different years were compared to demonstrate the evolving features. Seven typical beach profiles were selected to study the lateral beach variation characteristics. Continuous wind and wave observation data from Beihuangcheng ocean station during 2009 were employed for the hindcast of the local wave environment using a regional spectral wave model. Then the results of the wave hindcast were incorporated into the LITDRIFT model to compute the sediment transport rates and directions along the coasts and analyze the longshore sand movement. The results show that the coastline evolution of sand beaches in the southern Bohai Strait has spatial and temporal variations and the coast can be divided into four typical regions. Region （1）, the north coast of Qimudao, is a slightly eroded and dissipative beach with a large sediment transport rate; Region （II）, the southwest coast of Gangluan Port, is a slightly deposited and dissipative beach with moderate sediment transport rate; Region （III）, in the central area, is a beach that is gradually transformed from a slightly eroded dissipative beach to a moderately or slightly strong eroded bar-trough beach from west to east with a relatively moderate sediment transport rate. Region （IV）, on the east coast, is a strongly eroded and reflective beach with a weak sediment transport rate. The wave conditions exhibit an increasing trend from west to east in the off- shore area. The distribution of the wave-induced current inside the wave breaking region and the littoral sediment transport in the nearshore region exhibit a gradual weakening tendency from west t展开更多
文摘在处理分析海岸水陆特征时,引入水平集理论对复杂边界纹理特征信息进行提取。首先,对海岸线边界提取的相关研究及水平集理论进行了分析总结;然后,结合区域边界信息及其区域光滑非参数密度估计,引入海岸边界区域特征分割算法,利用多种类型的影像对该算法进行了验证;最后,为了说明水平集算法(level set method,LSM)对提取海岸线特征信息的有效性,对LSM算法与梯度下降方法在海岸线特征提取上的效率差异进行了比较。结果表明:LSM对海岸特征复杂纹理和噪声等信息具有一定的鲁棒性,同时对于有效边缘信息具有较强的检测灵敏度,能够迅速、有效地对其边界信息进行特征提取。
基金supported by the National Natural Science Foundation for the Youth(No.41106039)
文摘The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater topography, the wave environment in the offshore area is complex; beach types and sediment transport characteristics vary along different coasts. The coastlines extracted from six aerial photographs in different years were compared to demonstrate the evolving features. Seven typical beach profiles were selected to study the lateral beach variation characteristics. Continuous wind and wave observation data from Beihuangcheng ocean station during 2009 were employed for the hindcast of the local wave environment using a regional spectral wave model. Then the results of the wave hindcast were incorporated into the LITDRIFT model to compute the sediment transport rates and directions along the coasts and analyze the longshore sand movement. The results show that the coastline evolution of sand beaches in the southern Bohai Strait has spatial and temporal variations and the coast can be divided into four typical regions. Region （1）, the north coast of Qimudao, is a slightly eroded and dissipative beach with a large sediment transport rate; Region （II）, the southwest coast of Gangluan Port, is a slightly deposited and dissipative beach with moderate sediment transport rate; Region （III）, in the central area, is a beach that is gradually transformed from a slightly eroded dissipative beach to a moderately or slightly strong eroded bar-trough beach from west to east with a relatively moderate sediment transport rate. Region （IV）, on the east coast, is a strongly eroded and reflective beach with a weak sediment transport rate. The wave conditions exhibit an increasing trend from west to east in the off- shore area. The distribution of the wave-induced current inside the wave breaking region and the littoral sediment transport in the nearshore region exhibit a gradual weakening tendency from west t
