基于多时相遥感数据的九段沙潮滩高程获取

JIUDUANSHA INTERTIDAL ELEVATION ACQUISITION BASED ON MULTI-TEMPORAL REMOTE SENSING IMAGES

潮滩高程获取是掌握潮滩冲淤变化、合理开发潮滩资源的一项基础工作。针对潮滩高程常规测量成本高、工作量大的问题,讨论了基于多时相遥感数据的九段沙潮滩高程获取方法。该方法主要包括遥感影像选择、水边线自动提取,以及水边点的高程计算3个步骤。遥感水边线通常被当作等高线,但对于范围宽广的九段沙潮滩而言,水边线具有明显的起伏特征,不应该被简单地当作等高线。从九段沙2004年3个时相的LandsatTM影像中提取了3组不同高程水平的水边线;以水边线的顶点为水边点,依据九段沙周围4个潮位站在遥感影像采集时刻的瞬时潮位,采用简单趋势面插值法计算了所有水边点的高程。与潮滩实测数据对比分析的结果表明:水边点高程的平均绝对误差约为0.138m,精度约为93.74%。

Intertidal elevation acquisition is the fundamental work in understanding the intertidal sedimentation/erosion trend and reasonably developing intertidal resources.To counter the problem of high cost and effort to measure the intertidal elevation on the spot,this paper reports the development of an elevation acquisition method based on multi-temporal remote sensing images.The method mainly consists of three steps,i.e.remote sensing images selection,waterline extraction and waterpoint elevation calculation.Usually,the waterline is assumed as a contour.But Jiuduansha intertidal mudflat is so wide that the waterline is not horizontal completely and shouldn＇t be assumed simply as a contour.In this paper,three groups of waterlines are extracted from three Landsat TM images acquired under different tidal conditions in 2004.Taking all vertexes of one waterline group as a group of waterpoints,the authors calculate their elevations by using a simple trend surface interpolation based on the instantaneous tide levels of four tide stations around Jiuduansha.These waterpoint elevations are compared with the in situ measurement elevations.It is revealed that the average absolute error of the waterpoint elevations is about 0.138 m,and the precision is about 93.74%.