测绘工程专业英语翻译Unit 6.pdf

Unit 6 Methods of Elevation Determination 高程测量方法 An elevation is a vertical distance above or below a reference datum 高程是高于或 低于一个参考基 准的一个垂直距离 Although vertical distance can be referenced to any datum in surveying the reference datum that is universally employed is that of mean sea level MSL 虽然 垂直距离可以参考任何一个基准 但是在测 量上 这个参考基准一般使用 employ 使用 雇佣 的是平均海平面 MSL MSL is assigned a vertical value elevation of 0 000 ft or 0 000 m MSL 被赋予 assign 一个 0 000 英尺或 0 000 米的高程 All other points on the earth can be described by the elevations above or below zero 地球上所有 其它点可以用高于或低于 0 的高程来描述 Permanent points whose elevations have been precisely determined benchmarks are available in most areas for survey use 高程精确测出的永久点 水准点 被用于 available 可利用 可用到的 大多数区 域的测量工作 In China 7 years of observations at tidal stations in Qingdao from 1950 to 1956 were reduced and adjusted to provide the Huanghai vertical datum of 1956 在中国 利用青岛验潮站 tidal stations in Qingdao 从 1950 年到 1956 年 7 年的观测数据处理 reduce 处理 分析 减少 和平差 建立了 56 黄海高程系统 In the 1987 this datum was further refined to reflect long periodical ocean tide change to provide a new national vertical datum of 1985 according to the observations at tidal stations from 1952 to 1979 1987 年 在依照了 according to 验潮站 1952 到 1979 年的观测资料后 这个基准 56 基准 被进一 步精确 refine 精确 精制 v 反映长时期海潮变化的 85 国家高程基准建立 起来 Although strictly speaking the national vertical datum may not precisely agree with the MSL at specific points on the earth s surface the term MSL is generally used to describe the datum 虽 然 严格说来 strictly speaking 国家高程基准在特殊的 specific 特定的 特殊的 点上与 MSL 并不恰 好 precisely 吻合 术语 MSL 一般 generally 还是用来描述它 国家高程基 准 MSL is assigned a vertical value elevation of 0 000 ft or 0 000 m MSL 高程的 赋值为 0 000 英尺或 米 Difference in elevation may be measured by the following methods James M Anderson and Edward M Mikhail 1998 高程的差异 高差 可以由下列方法测得 詹姆斯 安德森和爱德华 1 Direct or spirit leveling by measuring vertical distances directly 水准测量 Direct leveling spirit leveling 都是水准测量的意思 直接测得垂直距离 高程 Direct leveling is most precise method of determining elevations and the one commonly used 水准 测量是高程测量方法中精度最高 使用最普遍的方法 2 Indirect or trigonometric leveling by measuring vertical angles and horizontal or slope distances 三角高程测量 利用测量竖直角和水平或斜距来测高程 3 Stadia leveling in which vertical distances are determined by tacheometry using engineer s transit and level rod plane table and alidade and level rod or self reducing tacheometer and level rod 视距高程测量 利用视距测量 tacheometry 使用工程经纬仪和水准尺 平板仪和照准仪和水准尺 或者自 处 理视距仪 tacheometer 视距仪 准距仪 和水准尺测得垂直距离 高程 4 Barometric leveling by measuring the differences in atmospheric pressure at various stations by means of a barometer 气压水准测量 Barometric 大气压力 通过使用气压计 barometer 测量不同站点 大气压力的差值来测高程 5 Gravimetric leveling by measuring the differences in gravity at various stations by means of a gravimeter for geodetic purposes 重力水准测量 通过使用 by means of 重力计测量不同站点的重力值 差值来测高程 用于大地测量学的目的 6 Inertial positioning system in which an inertial platform has tree mutually perpendicular axes one of which is up so that the system yields elevation as one of the outputs 惯 性定位系统 含有一个惯性平台 具有三个互相 mutually 相互地 垂直 perpendicular 垂直的 轴 其中一个是 向上 的 所以这个系统产生 yield 产生 v 的输出 output 输出 n 其中一个就是高 程 Vertical accuracies from 15 to 50 cm in distances of 60 and 100 km respectively have been reported 各自地 respectively 据相关报告 在 60 和 100km 的距离上 其精度能达到 15 到 50cm The equipment cost is extremely high and applications are restricted to very large projects where terrain weather time and access impose special constraints on traditional methods 这种装置成 本极 extremely 极端地 高 只限于 restricted 受限的 非常大的项目 这些项 目地质 气象 授时 以及 施加 impose 特殊限制 constraints 在传统方 法上 即 在这些项目上传统测量方法受限 7 GPS survey elevations are referenced to the ellipsoid but can be corrected to the datum if a sufficient number of points with datum elevations are located in the region surveyed GPS 高程测量 它的参考 面是地球椭球面 但是如果在测区有充 分的高程点 可以修正至高程基准上来 Standard deviations in elevation differences of 0 053 to 0 094 m are possible under these conditions 在这种情况下 上句中的情况 其高差的标准差 Standard deviation 能够达到 0 053 到 0 094 米 Spirit leveling 水准测量 The most precise method of determining elevations and most commonly use method is direct leveling or spirit leveling which means measuring the vertical distance directly 精度最高 使用最普遍的高程 测量方法就是直接测垂直距离的水准测量方 法 Differential leveling is used to determine differences in elevation between points that are remote from each other by using a surveyor s level together with a graduated measuring rod 微差水准测 量是利用测量者的水准仪 level 水准仪 水平仪 和 together with 有刻度的 graduated 尺来测定远距 离的 remote 遥远的 相 隔点的高差 For example to determine the elevations of desired point B with respect to a point of known elevation A see Figure 1 the elevation of which BM is known to be above sea level the level is set up at intermediate point between A and B and rod readings are taken at both locations as a and b respectively 例如 确定欲测 desired 想 得到的 关于点 A 的点 B 的高程 如图 1 A 点的高程已知 BM 点 above sea level 不用翻译 在 A 和 B 点之间的中 intermediate 居中的 点处安置水 准尺 分别 respectively 分别地 以 a 和 b 代表在这两处水准尺上的读数 Then the elevation of the line of sight of the instrument being horizontal is known to be the line of sight of the instrument HA a 那么 仪器 整平后 的视线高程 就是 HA a 怀疑这句话不对 the line of sight of the instrument 多余了 The elevation of point B can be determined by equation B 点的高程可以由方程 equation 来确定 HB HA a b In addition to determining the elevation of point B the elevations of any other points lower than the line of sight and visible from the level can be determined in a similar manner 除确定 B 点的 高程之外 In addition to 除 之外 其它点的高程 低于视线的 高于视线的点 水准仪无法测得读数 和水准仪可以看见的点 都可以 以相似的方法得到 But some terms should be mentioned from above 但是上面的一些术语需要提一下 a is called Backsight BS which is a rod reading taken on a point of known elevation in order to establish the elevation of the instrument line of sight a 被称为 Backsight 后尺读数 是一个放在已知高程 点上的尺的读数 用来求得 establish 建立 仪器视线的高程 b is called Foresight FS which is a rod reading taken on a turning point benchmark or temporary 是一个放在转点 turning 水准点 或者是临时水准点之上的尺的读数 用来确定该点的高程 HA a refers to the Height of Instrument HI which is the elevation of the line of sight through the level HA a 指的是仪器高度 HI 是过水准仪的视线的高程 Owing to refraction actually the line of sight is slightly curved the effects of curvature and refraction for the horizontal distance can be reduced to a negligible amount and no correction for curvature and refraction is necessary if backsight and foresight distances are balanced in practical operation 由于 Owing to 因 的缘故 大气折光 refraction 折光 的缘故 实际上视线是有些 slightly 些微地 弯曲的 曲率 地球曲率 和折光的影响可以被当作 be reduced to 被处 理为 可忽略的 negligible 可忽略的 值 amount 数量 不必 necessary 必要的 加入球气改正 如果在实 际 practical 工作 operation 中后视距和前视距是相等的 可提前到本句中间 Trigonometric Leveling 三角高程测量 Trigonometric leveling is used where difficult terrain such as mountainous areas precludes the use of conventional differential leveling 三角高程测量适用于困难地 形 例如在山区 不能 preclude 排 除 v 使用常规的 conventional 微差水 准测量 The modern approach is to measure the slope distance and vertical angle to the point in question 现代的三角高程测量方法是测量到未知点 the point in question 的斜距和垂直角 Slope distance is measured using electromagnetic distance measurers and the vertical or zenith angle using a theodolite or the total station that integrate these two instruments into a single instrument 斜距由电磁波测距仪 measurer 测量器 测得 垂直角 或天顶距 由经纬仪测得 或者利用整合 integrate 整合 v 了这 两种仪器为一体的全站仪来测 Total stations contain built in microprocessors that calculate and display the horizontal distance from the measured slope distance and vertical height 全站仪 包含了 contain 内置的 built in 内 置的 微处理器 用来根据测得的斜距和垂 直角计算和显示水平距离 This latter facility has resulted in trigonometrical leveling being used for a wide variety of heighting procedures including contouring 这种后来的 latter 设备 facility 工具 设备 熟练 容易 敏捷 导致了 result in 导致 三角高程测 量被广泛用于多种 a variety of 多种的 高度测量工作 procedure 程 序 手 续 包括测绘等高线 contour 等高线 The basic concept of trigonometrical leveling can be seen from Figure 2 三 角高程测量的基本原理 concept 概念 可以看图 2 When measuring the vertical angle and the horizontal distance S is used then the difference in elevation hAB between ground points A and B is therefore 当我们用 和 S 分别表示垂直角和水平距离 时 A 点和 B 点之间的高差为 hAB S tan i v where i is the vertical height of the measuring center of the instrument above A and v is the vertical height of the center of the target above B i 是 A 点上仪器中心的高度 v 是 B 点 上目标中心的垂直高 度 The vertical angles are positive for angles of elevation and negative for angles of depression 垂 直角为仰角 elevation 仰角 时为正 俯角 depression 俯角 时为负 The zenith angles are always positive but naturally when greater than 90 they will produce a negative result 天顶距总是正的 但是自然的当超过了 90 时 它们将产生一个相反的结 果 指的是相对于地平线 来说 Trigonometrical leveling method of determining difference in elevation is limited to horizontal distance less than 300 m when moderate precision is sufficient and to proportionately shorter distances as high precision is desired 普通 moderate 普 通的 精度要求下 sufficient 充足的 precision 精 度 三角高程测量方法测高差水平距离不能超过 300m 如果要求高的精度 则要相 应 proportionately 相应 地 缩短距离 For the distance beyond 300 m the effects of curvature and refraction must be considered and applied 因为超过 300m 时 地球曲率和折光影响必需考虑 apply 应用 可以不翻译 To eliminate the uncertainty in the curvature and refraction correction vertical angle observations are made at both ends of the line as close in point of time as possible