基于变焦数据模型的数字地图的研制

数字地图作为一种新型的地图受到人们越来越广泛的关注。数字地图包含着各种地图数据,为了在多种比例尺范围内能快速地检索地图数据,需要把地图数据分层存贮变焦。作者通过变焦数据模型原理,探讨如何建立多层存贮结构,将数字地图中的大比例尺地图数据库自动导出小比例尺图形。变焦数据模型是一种动态的数据模型, 在该模型中,图形比例尺的变化不是简单的图形尺寸的缩放,而是伴随着各个物体的细节和物体数量而增减。这种基于变焦数据模型建立的数字地图可以提高数据检索与图形表示的灵活性,减少大量不必要的用于重复获取数据而消耗的人力物力,广泛应用于各个领域。

Research and Application of Digital Map Based on Changed-focuses Datum Model

A newfashioned map, Digital Map, has aroused more and more public concern. It corresponds to Mapping Database, which includes all kinds of map datum. For rapidly searching map data at various scales, map data needs storing layeredly by "changing focuses". The Primary Problem of Changed-focuses Model is about establishing many layers stored-frame. This paper discusses how to establish multilayer storage structure and automatically reduce small scale graph from large scale mapping database by theory of changed-focuses Datum Model. Changed-focuses Datum Model is dynamic datum model, in which the change of graph scale is not only the zoom in graph measurement but the increase and decrease with object details and quantities. Digital Map Based on Changed-focuses Datum Model heightens agility in searching datum and graph expression, which reduces much unnecessary manpower and material resources used for repeatedly capturing data. So it is used in many fields.