准确、定量地把握土地利用及其变化状况具有重要的意义。全球定位系统(GPS) 在土地利用动态监测中既是遥感技术的辅助定位手段,也可以作为独立的数据获取手段。介绍了GPS定位方式和特点,结合中国国家“九五”攻关项目,讨论了县级土地利用动态监测中的GPS选型思路和综合考虑GIS功能的GPS数据获取方法。通过实验证明了2D异常数据处理方法和GPS数据处理中“假54”代替“真54”的可行性。这些结论将有效地提高内、外业工作效率和数据精度。

Withthe advance ofthesociety and economy, land is decreasing rapidly.Governmentneedsexactand quan titative data aboutlanduse statusto make reasonable decisions. However, traditional methods concerning dynamic moni toring oflanduse havelow efficiency and poor precision.Therefore, a better method tosolvethis problem isneeded.The developmentof Space Science gives us a chance. Remote Sensing can forwardly find the changed regions, Global Posi tioning System can determinethe accuratelocations oftheregions, and GeographicalInformation System can manage vari ous data asa platform.GPScan notonlyserve asan auxiliary positioning meansafterhavingfoundthetargetregionsfrom remote sensing data, butalso actas an independent data acquisition method.This paperfirstlyintroduces several basic GPSpositioning methods and their precision, and then, discusses the requirements of dynamic monitoring oflanduse at countylevel, which decidesthe modelselection of GPSreceiverand working pattern of GPS'outdoorsurveying.Combin ing a key projectof"the Ninth Five year Plan", the authors describefive kindsof GPSacquiring data methods with com prehensive consideration of GIS'functions.The disadvantageoussurveyingconditions willleadthecreation of"2Dabnor mal data", which can notreflectthetrue world. Deletingthe "2Dabnormal data"from original data set can provide an alternative with good authenticity.Deletingthe "2Dabnormal data"meansthe loss of acquired data.But under certain conditions, thisloss will notaffectthe computation results'precision and reality.The data acquired by GPSreceiversis based on WGS 84, but our basic databaseis on Beijing 54.Rationalresolventis "true 54"theoretically.Here, "pseu do 54"thoughtis proposed and proved feasible in Jiaoqu County, Baotou City by a large number oftests.The conclu sions could effectivelyimprovethe efficiency ofindoorand outdoor work, and improve data precision.