期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2001
卷号：XXXIV-4/W5
页码：61-68
出版社：Copernicus Publications
摘要：This paper introduces the author's work on the compression of vector geospatial data intended for transport on the Internet. WebGIS vector data format is shifting to ASCII code such as XML. In some applications, however, the technique of vector map data compression is still needed. The author proposes four innovations regarding WebGIS vector spatial data compression. (1) Not only integer, but also short data can be used to replace traditional double or float data of WebGIS. (2) A formula to calculated width of 'virtual screen' is proposed, (the formula is 'vituralScreenWidth = dispWidthPixel*maxEnlargeRatio / stepWidth'). The 'virtual screen' is used to map the original double or float geographic coordinate data to short data. In this formula, if stepWidth equals 1, the compression has no loss in precision. If stepWidth is larger than 1, the compression is less precise. (3) Three ways of dealing with the special case of long segments are proposed in the paper. The first is 'long segment add points', which fits in with having only few long segments. The second is 'long-short segments grouping', the third is 'respective deal with on layer', the second and third ways fit in the case many long segments, such as a traffic route map or street block map. After these operations a vector data map may be compressed to 1/5 or less than the original data. And (4) when the 'vituralScreenWidth' is given different values, it can form a 'hierarchy' of geospatial data versions, somewhat like cartographic generalization, but having the problem of feature selection
关键词：WebGIS; vector geospatial data; data compression; cartography generalization
