**EXTRACTING THE INFORMATION OF COASTLINE SHAPE AND ITS
MULTIPLE REPRESENTATION**

Y. Liu, Y. Zheng, G. Li, S. Li

*Department of hydrography and cartography, Dalian, China*

*liuyingwmt@163.com*

With the spread of GIS application field continually, an exigent
demand has been produced that is analysis and display the multiple scale
spatial data, and it has become the key problem in GIS. In order to realize the
true multiple representation of spatial data, we can solve it only by map
automatic generalization thoroughly. This paper researches the coastline and puts
forward the valid way of multiple representation. Simulating human thinking way
when they generalized, building the appropriate math model and describing the
coastline with graphics, extracting all kinds of the coastline shape
information, the coastline automatic generalization will be finished based on
the knowledge rules and arithmetic operators. The main contents as follows:

1.Showing the information of coastline shape with math method. We can express the information by building the curve Douglas binary tree directly and vividly. The curve Douglas binary tree can reveal the shape character of coastline not only microcosmically but also macroscopically.

2. Extracting the information of coastline. It concludes the local characteristic point and its orientation, the curve structure and the topology trait. The curve structure can be divided the single curve and the curve cluster.

3. The multiple scale representation of the coastline. By confirming the knowledge rules of the coastline generalization, the generalized scale and its shape parameter, the coastline automatic generalization model is established finally.

The method of the
multiple representation of coastline in this paper has some strong points. It
is human’s thinking mode and can keep
the nature character of the curve prototype. The binary tree structure can
control the coastline comparability, avoid the self-intersect phenomenon and
hold the unanimous topology relationship.