本文基于Morphing连续变形技术的一种技术探讨河网的多尺度变换方法,主要涉及对应河流间的Morphing变换和无对应河流的河流删除这两类问题.本文首先对两个不同比例尺的对应河网进行河流匹配,确定河流的对应情况,然后以较大比例尺河网向较小比例尺河网变化的方式进行河网的多尺度变换.对于在两个不同比例尺河网中对应存在的河流,采用顾及交汇点信息及河流结构信息的形状内插方法进行Morphing变换;对于仅在较大比例尺河网中存在而在较小比例尺河网中不存在的河流,则以河流的干支总长作为其重要性标准,进而依据给定的变换程度参数删除重要性较小的河流.最后,通过实验分析与对比,验证了本文方法能够有效改善河流间的Morphing变换效果,提高河流选取的准确性.

River network is a typical spatial entity in the real world and its multi-scale transformation is a hot issue in the field of cartography and geographical information science. This paper proposes a multi-scale transformation approach for river network, which is based on morphing technology. This approach involves two cases. One is to make transformation between two corresponding rivers, and the other is for some rivers represented only on the larger-scale map. As for the first case, shape interpolation is utilized for morphing, where the intersections between rivers and the structures of rivers themselves are considered. For the second case, an indicator is defined by the total length of a river and its tributaries, and is employed to measure the importance of the river. By this indicator, some rivers of low importance, which are represented only on the larger-scale map, may be deleted in the process of multi-scale transformation. Through the case study, it is shown that the approach proposed in this paper can improve the results of morphing between rivers as well as the accuracy of river selection in the process of multi-scale transformation.