Abstract:
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
Sxt of plane projection of surface feature on map,etc.(2) The definition of scale symbolicIf the boundary
Wx of
Sxt suffices the following condition:
Wx=
P|
P∈ Ext min
O∧
Sxt=
f(
wx),then the
Sxt calls the scale symbol with
Wx as boundary.(3) The definition of Non-scale symbolicIf
Sxt min
O condition is sufficed and the median point of
Sxt is the centre of limit circle min
O,then the median point of
Sxt 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.