MapObjects中扩展地图注记功能的算法设计与实现

The Algorithm Design and Implementation of Broadening Map Annotation Functions With MO

地图注记是地图制图领域的重要内容,能够增强地图内容的易理解性。不论是普通地图还是专用地图,注记都起着联系制图者和使用者的桥梁和纽带作用。本文结合实际项目"河南省航道基础地理信息系统"的研发研究了利用Visual Basic和MapObjects扩展地图注记功能的有关原理、算法和步骤。文字注记主要由MapObjects的注记对象LabelPlacer Object来实现。在地物符号的开发过程中,用Font Creator字体工具设计点符号来实现点状符号的绘制和建库过程,平行线和铁路符号的开发则通过创建类模块分别采用角平分线法和平行线法实现。

Map annotation is an indispensable composition of cartography and it is helpful for users to understand lnap content quickly.Annotation either in ordinary maps or in special maps is a bridge between the mappers and the users. In this paper, it is studied the principle, arithmetic and approaches of broadening map annotation functions with VB and MO for the project of Water Way Basic Geography Information System in He＇nan. The character annotation function has been realized by the LabelPlacer Object which is provided by MapObjects, the discreteness of ESRI. During development of object symbols, the customized point symbols are created by Font Creator tools. The parallel and rail symbols are created by constructing the class modules with the angular bisector algorithm and the parallel algorithm separately.