测绘专业英语教案5.docx

1、测绘专业英语教案5 教 案2008 2009 学年第 一 学期主 讲 教 师周 保 兴课 程 名 称测 绘 专 业 英 语 课程类别专 业 选 修 课学时及学分45学时 3个学分授 课 班 级测绘061062使 用 教 材测 绘 工 程 专 业 英 语系(院、部)土木工程系教研室(实验室)测绘工程教研室课时授课计划课次序号： 5 一、课题：Unit5 Traversing二、课型： 讲 授三、目的要求：To determine horizontal positions of arbitrary points on the earths surface and elevation of poin

2、ts above or below a referenc surface are known as a control survey. The generally used methods are triangulation, trilateration, traversing, intersection, resection and GPS.The main topic of this text refers to the traversing:(1) Triangulation Defined(2) Trilateration Defined(3) Traversing Defined四、

3、重点、难点：(1) Triangulation (2) Trilateration (3) Traversing 五、教学方法及手段：本次课程的教学内容为导线测量方法的英文表达方式，在理解测绘专业知识的基础上，着重学习测绘专业知识的英文表达方式和写作方式，根据以上教学内容和教学目的本次课采用讲授的教学方式。同时为了提高学生的学习积极性，达到预定的教学效果，拟采用课堂讲授和课堂提问相结合的教学方式。六、参考资料：(1)测绘工程专业英语 尹 晖等 武汉大学出版社七、作业：(1) 预习 Unit6 Methods of Elevating Determination八、授课记录：授课日期2008.1

4、0.20班次测绘061、062九、授课效果分析： 通过对Traversing的内容的学习，使学生掌握了文章中涉及到的重点的测绘专业词语、词组、表达方式和测绘专业英语的翻译方式，对导线测量有了基一步的理解，同时，掌握了导线测量的英文表达方式。十、教学进程（教学内容、教学环节及时间分配等）1、导入课题：由前面学习的大地测量、平面测量、距离及角度测量的基础知识及其英文的表达方式，根据大地测量和平面测量的定义，导线测量是确定地面点位的基本方法之一。2、教学内容：本次课的内容为Traversing，包括导线测量概述、三角测量和三边测量概念、导线测量确定点位的方法。 (1) 预习一下Words and E

5、xpressions、Terms Highlights了解有导线测量的定义和方法的词汇和专业的表达方式。(2) 预习课程中正文的内容,让学生熟悉一下课程内容。(3) 结合测绘工程专业知识，对课文的内容进行讲解，在讲解的过程中结合课堂提问，以便使学生能主动的结合所学的专业知识和英语理解能力，对测绘专业英语有深刻的理解。Unit 5 Traversing （导线测量）The purpose of the surveying is to locate the positions of points on or near the surface of the earth.（测量的目的是确定地表或接近地

6、表的点的点位。）To determine horizontal positions of arbitrary points on the earths surface and elevation of points above or below a reference surface are known as a control survey.（确定地表任一【arbitrary任意的】点的平面位置和确定点高于或低于一个参考面的高程的工作被称为控制测量）The positions and elevations of the points make up a control network.（这些

7、点的平面位置和高程组成了一个控制网）There are different types of control networks depending on where and why they are established.（依照它们建立的地点和目的不同，有不同的控制网类型）A control network may have very accurate positions but no elevations (called a Horizontal Control Network) or very accurate elevations but no positions (called a

8、Vertical Control Network).（一个控制网可能有精确的平面位置而没有高程（称为平面控制网），或者有精确的高程而没有平面位置（称为高程控制网）Some points in a control network have both accurate positions and elevations.（有些控制网的点既有精确的平面位置也有精确的高程）Control networks range from small, simple and inexpensive to large and complex and very expensive to establish.（控制网的范

9、围从小的、简单的、便宜的网到大的、复杂的、昂贵的网）A control network may cover a small area by using a “local” coordinate system that allows you to position the features in relation to the control network but doesnt tell you where the features are on the surface of the earth, or cover a large area by consisting of a few wel

10、l-placed and precise-established control points, which is sometimes called the primary control.（一个控制网可以是覆盖小范围，使用区域坐标系统，允许你相对于控制网确定地貌特征【feature】，但却不告诉你它们在地表的什么地方；或者覆盖一个广大区域，由少数被适当安置并精确测设的控制点组成，有时被称为基础控制）The horizontal positions of points in a network can be obtained in a number of different ways.（控制网

11、的点的平面位置可以由许多不同方法来获得）The generally used methods are triangulation, trilateration, traversing, intersection, resection and GPS.（一般使用的方法有，三角测量、三边测量、导线测量、交会测量、后方交会测量、和GPS测量）The main topic of this text refers to the traversing.（这篇课文主要讲的是导线测量）Triangulation（三角测量）The method of surveying called triangulation

12、 is based on the trigonometric proposition that if one side and three angles of a triangle are known, the remaining sides can be computed by the law of sines.（这种测量方法称为三角测量，基于三角【trigonometric三角法的】法则【proposition命题】，【that引导的宾语从句】如果三角形的一条边和三个角已知，剩下的边可以用正弦定理【law of sines】计算出）Furthermore, if the direction

13、 of one side is known, the direction of the remaining sides can be determined.（而且，如果一条边的方向已知，余下的边的方向也可以确定）And then coordinates of unknown points can be computed by application of trigonometry.（那么未知点的坐标就可以使用三角法计算出来）Trilateration（三边测量）Since the advent of long-range EDM instrument, a method of surveyin

14、g called trilateration was adopted to combine with triangulation.（自从远距EDM出现【advent出现】以来，一种叫做三边测量的方法用来和三角测量联合使用。）The trilateration is based on the trigonometric proposition that if the three sides of a triangle are known, the three angles can be computed by the law of cosines.（三边测量基于三角法则如果三角形的三条边已知，那

15、么三个角可以由余弦定理【law of cosines】计算出）Trilateration possesses some advantages over triangulation because the measurement of the distances with EDM instrument is so quick, precise and economical while the measurement of the angles needed for triangulation may be more difficult and expensive.（三边测量具有【possess拥

16、有、具有】一些相对于三角测量的优势，EDM测距快速、准确、经济，而三角测量所需的角度测量则相对困难和昂贵）For some precise projects, the combination of triangulation and trilateration which is called triangulateration is applied.（在一些精密工程当中，三角测量和三边测量联合使用，被称为边角测量）Traversing（导线测量）A survey traverse is a sequence of lengths and directions of lines between

17、points on the earth, obtained by or from field angle and distance measurements and used in determining positions of the point.（【测量工作中的】导线是一系列【sequence次序、系列】地球上点之间的有长度和方向的直线，【导线】由野外角度和距离测量获得，用来确定点位）The angles are measured using transits, theodolites, or total stations, whereas the distances can be me

18、asured using steel tapes or EDM instruments.（角度可以使用经纬仪或全站仪来测，而【whereas】距离可以使用卷尺或EDM来测）A survey traverse may determine the relative positions of the points that if connects in series, and if tied to control stations based on some coordinate system, the positions may be referred to that system.（导线可以用来

19、确定互相连接点的相对位置【relative position】，如果想控制某些坐标系中的站点【以某坐标系的点为站点】，其【指stations】位置应参考该坐标系）From these computed relative positions, additional data can be measured for layout of new features, such as buildings and roads.（从这些计算出的相对位置，另外的数据可以量出来，用以放样【layout】新的地物【features特征，理解为地物】，如：建筑物和道路。）Since the advent of ED

20、M equipment, traversing has emerged as the most popular method to establish control networks such as basic area control, mapping, control of hydrographic surveys and construction projects.（自从EDM的出现【advent】，导线测量作为最常用的建立控制网的方法显现【emerge显现】出来，例如基础区域控制、图根控制、水道测量控制和建筑工程控制【建筑施工控制】）In engineering surveying,

21、 it is ideal way to surveys and dimensional control of route-type projects such as highway, railroad, and pipeline construction. （在工程测量当中，导线测量是线型工程测量和立体【dimensional空间的】控制的理想方法，线型工程例如公路、铁路、和管线建筑） In general, a traverse is always classified as either an open traverse or a closed traverse.（总体上【In gener

22、al】，导线总是分为支导线和闭路导线【按说open traverse是支导线，closed traverse是闭合导线，而connecting traverse是附合导线】）An open traverse originates either at a point of known horizontal position with respect to a horizontal datum or at an assumed horizontal position, and terminates at a station whose relative position is not previo

23、usly known.（支导线起始于【originate起源】一个水平位置已知（相对于一个水平基准【水平坐标系】）或水平位置假定的点，终止【terminate】于相对位置【relative position】事先未知的站点。）The open traverse provides no check against mistakes and large errors for its termination at an unknown horizontal position and lack of geometric closure.（由于其终点位置未知并且缺乏图形闭合【geometric几何的】【

24、closure闭合n.】，支导线不能提供对错误和较大误差的检核）This lack of geometric closure means that there is no geometric verification possible with respect to the actual positioning of the traverse stations.（这种图形闭合的缺少意味着没有几何上的检核【verification检核】可能性【possible可能性n.】，对于实际的导线点的确定。【对于实际导线点的测量来说，这种图形闭合的缺少意味着没有几何检核条件】）Thus, the meas

25、uring technique must be refined to provide for field verification.（因而，这种测量技术应当提供野外的检核使之精确【refine精炼】。）【字面的意思是该技术应当被精确化提供给野外确认【verification确认、核实】At a minimum, distances are measured twice and angles are doubled.（至少【minimum最小值】，距离测两遍，角度测两个测回。）Open traverses are often used for preliminary survey for a r

26、oad or railroad.（支导线经常用于道路或铁路的初测【preliminary survey】）A closed traverse can be described in any one of the following two ways:（闭路导线可以由下面两种方式的任一种描述：）A closed loop traverse, as the name implies, forms a continuous loop, enclosing an area.（闭合环路导线，正如名字所示，呈一个连续的环，围绕【enclose】一个区域）This type of closed traver

27、se starts at assumed horizontal position or at a known horizontal position with respect to a horizontal datum and ends at the same point.（这种闭路导线起始于一个平面位置假设或相对于一个水平基准【坐标系统】已知的点，并终止于该点）A connecting traverse starts and ends at separate points, whose relative positions have been determined by a survey o

28、f equal or higher order accuracy.（附合导线起始和终止于不同【separate】的点，它们【起点与终点】由等于或高于规定精度的测量测设）A known horizontal position is defined by its geographic latitude and longitude, or by its X and Y coordinates on a grid system.（一个已知的水平位置是由它的大地经纬度【geographic latitude大地纬度；geographic longitude大地精度】或格网系的X Y坐标表示【define

29、】）Closed traverses, whether they return to the starting point or not, provide checks on the measured angles and distances.（闭合导线，无论它们是否回到起始点，都能提供角度和距离检核。）In both cases, the angles can be closed geometrically, and the position closure can be determined mathematically.（在两种情况中，角度可以在几何上闭合，位置闭合可以数学的确定【计算出

30、来】）Therefore they are more desirable and used extensively in control, construction, property, and topographic surveys. （因此它们更理想【desirable理想的】，在控制测量、建筑测量、房地产测量和地形测量使用更广泛）As we mentioned above, a closed traverse provides checks on the measured angles and distances.（正如我们上面所提到的【如上所述】，闭合导线可以提供角度和距离的检核）Fo

31、r example, the geometric sum of the interior angles in an n-side closed figure should be (n-2)180, but due to systematic and random errors of the measurements, when all the interior angles of a closed traverse are summed, they may or may not total the number of degrees required for geometric closure

32、.（例如，在一个n边闭合图形当中，内角【interior angle】和【geometric几何的 可不翻译】应该是：(n-2)180，但是由于【due to】测量中系统误差和偶然误差的存在，当闭合导线所有的内角加起来后，其角度和【total】可能等于或不等于其几何理论闭合差值）The difference between the geometric sum and actual field sum of the interior angles is called angular closure.（内角和的理论值【geometric几何的】和实际值的差值被称为角度闭合差【angular关于角的】【closure闭合度】）The total error of angular closure should be distributed evenly to each angle (if all angles were measured with the same