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海岸线变迁的研究,有着较为重要的现实意义。当前,对于涉及两个时期间海岸线蚀退型和淤积型区域的构建研究,尚缺乏较为自动准确的方法。将两个时期的海岸线视为有向且无自相交的曲线,相互打断为若干有向折线段。通过总结各类型区域边界的构成规律,得出若干结论,继而提出两时期海岸线间变迁区域的自动构建算法。构成变迁区域边界的海岸线折线段,总是两个时期间隔出现,且有相同的起点或终点,移除构成某一变迁区域的所有折线段后,对其它区域的提取没有影响。据此规律,提取某一变迁区域边界上的所有折线段,利用其中的点构建区域,根据早期海岸线的方向(顺时针或逆时针),判断变迁区域的具体类型。随后编写功能模块,以实际海岸线数据进行验证实验,结果符合预期。借助该算法,可根据两个时期的海岸线,快速准确地提取出由水域变为陆地的淤积型区域和由陆地变为水域的蚀退型区域,为分析海岸线的时空变化特性提供辅助作用。
The study of coastline change has more important practical significance. At present, there is a lack of a more automatic and accurate method for the study of the construction of eroded and silted coastal areas during the two periods. The coastlines of both periods are treated as directed and non-self-intersecting curves, which are interrupted into several directed polyline segments. By summarizing the formation rules of various types of regional boundaries, a number of conclusions are drawn, and then an automatic construction algorithm for the transitional areas between the coastlines in two periods is proposed. The polyline segments of the coastline that form the boundary of the transition region always appear at two time intervals with the same starting point or end point. After removing all the polyline segments that constitute a transition zone, they have no effect on the extraction of other regions. According to this rule, all the polyline segments on the boundary of a changing region are extracted, and the regions are used to construct the region. The specific type of the transition region is judged according to the direction of the early coastline (clockwise or anticlockwise). Then write functional modules to verify the actual coastline data experiments, the results in line with expectations. With the aid of this algorithm, the silting area from the water area to the land and the eroded area from the land area to the water area can be quickly and accurately extracted according to the coastline in two periods, which can be used to assist in analyzing the spatio-temporal variation characteristics of the coastline.