【正文】 that is, it is measured or designed to the right or to the left, or 。 to 360176。 .（它的范圍是從 0 到 180 度） Obviously the zenith angle is equal to 90176。） It is thus between 0176。 .（豎直角位于【 lie 位于】 0～ 90 度之間） Zenith is the term describing points on a celestial sphere that is a sphere of infinitely large radius with its center at the center of the earth.（天頂方向是一個(gè)術(shù)語(yǔ)，用來(lái)描述在天球【 celestial sphere 天球】上的點(diǎn)，天球是一個(gè)半徑無(wú)限【 infinitely 無(wú)限地】大的球，其中心在地球中心。 and 177。） The horizontal angle is used primarily to obtain relative direction to a survey control point, or topographic detail points, or to points to be set out.（水平角主要【 primarily】用來(lái)由聯(lián)測(cè)控制點(diǎn)獲 得 相對(duì)方向，或者地形測(cè)量碎部點(diǎn)、或者放樣點(diǎn)【 or to points to be set out 應(yīng)該是 or points to be set out 才對(duì)吧？？？ direction to a survey control point、 topographic detail points、 points to be set out 并列都是 obtain 的賓語(yǔ)。） At any point there are an unlimited number of horizontal lines.（過(guò)任一點(diǎn)的水平線有無(wú)數(shù)【 unlimited】 條。） At a given point there is only one vertical line.（在給定的一個(gè)點(diǎn)上只有一條垂線。 (3)Infrared systems with range up to 3 km, limited to line of sight and limited by rain, fog, other airborne particles. （ EDM 使用三種不同波長(zhǎng)的波段： (1)微波系統(tǒng)【波段】，其測(cè)距范圍達(dá) 150km，波長(zhǎng) 3cm，不受 限于視線范圍，也不受可見(jiàn)度的影響； (2)可見(jiàn)光波段，有效范圍 5km（小型儀器），可見(jiàn)光、激光， 其距離受可見(jiàn)度的影響會(huì)降低； (3)紅外線【 Infrared】波段，測(cè)程 3km，受限于視線范圍，并且受 限于空氣中的微粒影響） Although there is a wide variety of EDM instruments available with different wavelengths, there are basically only two methods of measurement employed which may divide the instruments into two classification as electrooptical (light waves) and microwaves (radio waves) instruments.（盡管不同的 EDM 用到不同的波長(zhǎng)，基 本上只有兩種測(cè)量方法在使用，可以將其【即 EDM】分為光電測(cè)距儀和 微波測(cè)距儀） These two basic methods are namely the pulse method and more popular phase different method. （這兩種 基本方法即【 namely 即】脈沖【 pulse】法和更流行的相位【 phase different 相位的不同】法） They function by sending light waves or microwaves along the path to be measured and measuring the time differences between transmitted and received signals, or in measuring the phase differences between transmitted and received signals in returning the reflecting light wave to source. （沿著要測(cè)的路徑發(fā)射 光波或微波，并測(cè)出發(fā)射和收到反射信 號(hào)之間的時(shí)間間隔，或者是測(cè)出發(fā)射和接受反射信號(hào)之間的 相差【 phase differences】，它們通過(guò)這種方法來(lái)運(yùn)行【 function v.】） Modern EDM instruments are fully automatic to such an extent that, after the instruments, set up on one station, emits a modulated light beam to a passive reflector set up on the other end of the line to be measured.（現(xiàn)代的 EDM 全自動(dòng)化到這樣的程度【 to such an extent that 到這樣的程度】，在一個(gè)站 點(diǎn)安置，需測(cè)距離線的另一處安置有反射棱鏡，發(fā)射一束已調(diào)制【 modulated 已調(diào)制的】的光束到 棱鏡上） The operator need only depress a button, and the slope distance is automatically displayed. （操作者僅僅 需要按一個(gè)鍵，斜距就自動(dòng) 顯示出來(lái)。） EDM instruments use three different wavelength bands: (1)Microwave systems with range up to 150km, wave length 3 cm, not limited to line of sight and unaffected by visibility。 （它們?cè)谡婵罩卸加幸粯拥乃俣? 299,177?！?emphasis 側(cè)重點(diǎn)】） Distance can now be measured easily, quickly and with great accuracy, regardless of terrain conditions. （現(xiàn)在距離可以被很容易、快速和精確的測(cè)量，而又不受地形【 terrain】影響。） Most instruments now used for stadia are equipped with internalfocusing telescopes.（現(xiàn)在大多數(shù)視距 儀器都使用內(nèi)調(diào)焦望遠(yuǎn)鏡） Applications of tacheometry include traversing and leveling for the topographic surveys, location of detail surveys, leveling and field pletion surveys for the topographic mapping, and hydrographic mapping. （視距測(cè)量的應(yīng)用包括地形測(cè)量【 topographic survey】中的導(dǎo)線測(cè)量【 traversing】和水準(zhǔn)測(cè)量 【 leveling】工作，細(xì)部測(cè)量【 detail survey】中的定位，繪制地形圖工作中的水準(zhǔn)測(cè)量和野外完全 化測(cè)量，以及水道測(cè)圖） The relative precision is 1:1000 to 1:5000.（其相對(duì)精度為 1:1000 到 1:5000） Stadia is a form of tacheometry that uses a telescopic crosshair configuration to assist in determining distances.（視距儀是視距測(cè)量的一種形式，利用望遠(yuǎn)鏡的十字絲結(jié)構(gòu)幫助測(cè)距） A series of rod readings is taken with a theodolite and the resultant intervals are used to determine distances. （一系列的標(biāo)尺讀數(shù)由經(jīng)緯儀測(cè)出，并且籍此而得到視距間隔，用來(lái)確定距離 【 resultant 由此產(chǎn)生的】） Electronic Distance Measurement(EDM) （電子測(cè)距儀） The Electronic Distance Measurement(EDM) was first introduced in 1950s by the founders of Geodimeter Inc.（電子測(cè)距儀的概念是由 Geodimeter【“光電測(cè)距儀”――商標(biāo)名】公司的創(chuàng)始人在 20 世紀(jì) 50 年代引入的。） Internalfocusing telescopes are so constructed that C is 0 or nearly so。） By reading the top and bottom stadia hairs on the telescope view and then the horizontal distance from center of instrument to rod can be obtained by multiplying the stadia interval factor K by the stadia interval and plus the distance C which is from the center of instrument to principal focus, . D=Ks + C. （通過(guò)望遠(yuǎn)鏡視野【 view】里的上下視距絲讀數(shù)，從儀器到尺的平距可以用視距常數(shù)【 stadia interval factor】 K 乘視距間隔【 stadia interval】加上從儀器中心到主焦點(diǎn)【 principal focus】的距離 C 得到。） Tacheometry and Stadia （視距測(cè)量和視距儀） Tacheometry is an optical solution to the measurement of distance.（視距測(cè)量是一個(gè)光學(xué)【 optical】測(cè) 距方法） The word is derived from the Greek Tas, meaning “ swift” , and metrot, meaning “ a measure” .（這個(gè)詞 源自于【 is derived from 源自于】希臘語(yǔ)的 Tas，意思 是“迅速的”，和 metrot【同樣是希臘語(yǔ)】， 意思是“方法”。） Such tapes have low precision in distance measurements with about 1/3000~1/5000.（這種尺的精度低， 測(cè)距精度只有 1/3000 到 1/5000） The precise taping refers to the steel tapes and which are much more expensive than the plastic tape and have higher precision of 1/10000~1/30000.（精密尺距測(cè)量使用的是比塑膠尺貴的多的鋼尺，并具有 更高的精度―― 1/10000 到 1/30000） Invar tapes are posed 35% nickel and 65% steel.（因瓦尺是由 35％的鎳和 65％的鋼組成） This alloy has a very low coefficient of thermal expansion, making the tapes useful in precise distance measurement. （這種合金具有非常低的熱膨脹【 thermal expansion】系數(shù)【 coefficient】，使得這種 尺利于精密距離測(cè)量） Many tapes are now graduated with foot units on one side and metric units on the reverse side. （現(xiàn)在許多 尺上都在正面標(biāo)刻【 graduate 標(biāo)刻、刻】了英尺計(jì)量單位，而在反面標(biāo)刻了米制計(jì)量單位） Metric units are in meters, centimeter and minimeter with the total length of 20 m, 30 m, 50 m and 100 m. （米制計(jì)量單位是米，厘米和毫米，尺的總長(zhǎng)為 20m、 30m、 50m 或 100m） If we want to measure the horizontal distance between the two points A