摘要
地形图CAD数据是GIS应用与开发的重要数据源,而相应空间参考缺失的情况却并不鲜见。该文分析了CAD数据的特点,并指出在实际应用中对空间参考缺失的处理存在一些不科学的方法;针对我国及地方数字地形图坐标系建立的一般规律,提出了CAD数据空间参考判断及其参数获取的方法:以大地基准及地图投影已知(高斯-克吕格投影)为前提,通过对比实际地图坐标和标准地图坐标在数值上的差异,确定北伪偏移量和东伪偏移量这两个地图空间参考的重要参数;针对不同的CAD地形图数据,用不同的实例说明了该方法的具体实施过程。
Digital topographic map in CAD format is an important data source for applications and development of GIS. However,the spatial reference information, which is the location basis of GIS data, is always neglected in CAD files. In this paper, a method is presented to determine the spatial reference and estimate the mapping parameters of CAD data. Firstly, the features of CAD maps are elaborated and some false means when using them as GIS data are analyzed. Then, the method is proposed based on the assumption that the Geodetic Datum and Map Projection（Gauss Kruger Projection）are already known and by using the criterion of reference frames for topographic maps in China. Considering the diverse coverage regions of the data, two significant map parameters, namely, False Northing and False Easting, are estimated by comparing the actual coordinates to the standard ones. Different types of digital topographic map in CAD format are selected as examples to illustrate the procedures and to assess the accuracy of the method. The results show that this method is efficient and effective in the spatial reference determination and parameters estimation of CAD data.
出处
《地理与地理信息科学》
CSSCI
CSCD
北大核心
2010年第2期35-37,84,共4页
Geography and Geo-Information Science
关键词
GIS
坐标系
空间参考
元数据
GIS
reference frame
spatial reference
metadata
