欢迎来到天天文库
浏览记录
ID:28470947
大小:76.50 KB
页数:11页
时间:2018-12-10
《测绘专业英语曲建光1lessonone翻译》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、LessononeIntroductiontoSurveyingSurveyingistheartofmakingsuchmeasurementsoftherelativepositionsofpointsonthesurfaceofEarththat,ondrawingthemtoscale,naturalandartificialfeaturesmaybeexhibitedintheircorrecthorizontalorverticalrelationships.测量是一种技术,它测定地球表酣上各点的相对位置,并按照比例绘制出来,使得天然和人工地物能以正确的水平或垂直关系展示出来。Le
2、sscomprehensively,theterm,“Surveying”,maybelimitedtooperationsdirectedtotherepresentationofgroundfeaturesinplan.Methodswherebyrelativealtitudesareascertainedaredistinguishedas“leveling”,theresultsbeingshowneitherasverticalsectionorbyconventionalsymbolsonaplan.较为全谢地说,“测量”这个词可以局限于在平面图上表示山地貌的操作。确定相对高度的
3、操作区别为水准测量,其结果或以纵断面显示或是在平面图上用惯用符号表示。Plane,AerialandGeodeticSurveyingAplanisprojectionuponahorizontalsurface,andinitsconstructionalllinearandangularquantitiesusedmustbehorizontaldimensions.Itisimpossibletogiveacompleterepresentationofdistancesfollowingtheundulationsofthegroundotherthanbyascalemodel.No
4、wahorizontalsurfaceisnormaltothedirectionofgravityasindicatedbyaplumpline,but,onaccountoftheformoftheEarth,thedirectionofplumplinessuspendedatdifferentpointsinasurveyarenotstrictlyparallel,andtheplanehorizontalatonepointdoesnotpreciselycoincidewiththatthroughanyotherpoint.Itisnottheirregularshapeoft
5、heEarth’sphysicalsurfacethatisrefferedtohere,butthealmostregularcurvatureofalevelsurfacewhichisnecessarilyperpendiculartotheverticaleverywhere.平面测量,航空测量,大地测量平面图是在水平面上的投影,在绘制吋使用的长度和角度的量值必须是水平分呈。除了用一个比例模型,完整地表示出地面的起伏下的距离是不可能的。一个水平面与铅锤线指示出的重力方叫是養直的,但是,由于地球的形状,在测M屮,不同点悬挂的铅锤线的方向不是严格平行的,并且一点的水平面不会精确地与其它任一
6、点的水平面重合。在此谈及的不是地球的物质表面的不规则形状,而是水准面的近乎规则的曲率。在任何地方,其必然垂直于竖直面。Insurveysofsmallextenttheeffectofcurvanceisquitenegligible,anditisjustifiabletoassumethatalevelsurfaceoftheEarthisahorizontalplanewithintheareacovered.SurveyingmethodsbasedonthissuppositionarecomprisedundertheheadofPlaneSurveying.Theassumpti
7、onbecomesinvalidintheaccuratesurveyofanareaofsuchextentthatitformsanappreciablepartoftheEarth’surface.Allowancemustbemadefortheeffectofcurvature,andtheoperationsbelongtoGeodeticSurveying.在小范围的测量中,曲率的影
此文档下载收益归作者所有