摘要
根据拓扑学和图论的有关定义及符号构形的知觉阈值 ,提出符号清晰描绘和表示的下极限———极限圆概念 ,通过地物在平面上投影的图上面积与极限圆的比较 ,推导了依比例符号、不依比例符号和半依比例符号的数学定义 ,从而使这三类地图符号的基本概念获得了精密的数学形式和定量描述。探讨了这三类地图符号的依存关系和相互转化的条件 ,使不依比例符号和半依比例符号随地图比例尺的缩小而数量倍增的规律得到了理论解释。
According to the scaled relation in the concerned catographic literatures,the cartographic symbols are classified into scale symbol,non_scale symbol and semi_scale symbol,whose mathematical definitions are produced in this paper.(1) The basic concepts applied in this paperThe internal point and external point in the topology;the trail and cycle in the graph theory;the consciousness thershold value of symbolic configuration in the map perception;the limit circle minO and the area S xt of plane projection of surface feature on map,etc.(2) The definition of scale symbolicIf the boundary W x of S xt suffices the following condition: W x={P|P∈ Ext min O∧S xt =f (w x)} ,then the S xt calls the scale symbol with W x as boundary.(3) The definition of Non_scale symbolicIf S xt <min O condition is sufficed and the median point of S xt is the centre of limit circle min O ,then the median point of S xt is called the characteristic point of non_scale symbol and the cartographic symbol with it as localized centre is called the non_scale symbol. (4) The definition of semi_scale symbolicAfter the characteristic point and localized line of semi_scale symbol were definde i.e.the cartographic symbol with semi_scale symbol localized line as its central line and indication x surface feature is called the semi_scale symbol.The relation of three classes cartographic symbol and their transformation condition are discussed in this paper.
出处
《武汉大学学报（信息科学版）》
EI
CSCD
北大核心
2001年第5期465-468,共4页
Geomatics and Information Science of Wuhan University
基金
广西自然科学基金资助项目 ( 9912 0 1)
