【正文】 向上下移動尺子， 我們在尺上將得到不同的的讀數(shù)【changes of reading 讀數(shù)的變化】）The shortest reading of the tape is the horizontal distance.（尺子最小的讀數(shù)就是平距）If the distance is longer than the length of tape, then we can divide the long distance into several segments and get the total distance by plus each segment together.（如果距離比尺長要長，那么【then】我們可 以將其分成幾段【segment】，把每段長加起來獲得總長。）Tacheometry and Stadia （視距測量和視距儀）Tacheometry is an optical solution to the measurement of distance.（視距測量是一個光學(xué)【optical】測 距方法）The word is derived from the Greek Tas, meaning “swift”, and metrot, meaning “a measure”.（這個詞 源自于【is derived from 源自于】希臘語的 Tas，意思是“迅速的”，和 metrot【同樣是希臘語】， 意思是“方法”。）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 stadiainterval and plus the distance C which is from the center of instrument to principal focus, . D=Ks + C. （通過望遠(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【principal focus】的距離 C 得到。） Internalfocusing telescopes are so constructed that C is 0 or nearly so。）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. （視距測量的應(yīng)用包括地形測量【topographic survey】中的導(dǎo)線測量【traversing】和水準(zhǔn)測量【leveling】工作，細(xì)部測量【detail survey】中的定位，繪制地形圖工作中的水準(zhǔn)測量和野外完全 化測量，以及水道測圖）The relative precision is 1:1000 to 1:5000.（其相對精度為 1:1000 到 1:5000）Stadia is a form of tacheometry that uses a telescopic crosshair configuration to assist in determining distances.（視距儀是視距測量的一種形式，利用望遠(yuǎn)鏡的十字絲結(jié)構(gòu)幫助測距）A series of rod readings is taken with a theodolite and the resultant intervals are used to determinedistances. （一系列的標(biāo)尺讀數(shù)由經(jīng)緯儀測出，并且籍此而得到視距間隔，用來確定距離【resultant 由此產(chǎn)生的】）Electronic Distance Measurement(EDM) （電子測距儀）The Electronic Distance Measurement(EDM) was first introduced in 1950s by the founders ofGeodimeter Inc.（電子測距儀的概念是由 Geodimeter【“光電測距儀”――商標(biāo)名】公司的創(chuàng)始人在 20 世紀(jì) 50 年代引入的。【emphasis 側(cè)重點】）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、快速和精確的測量，而又不受地形【terrain】影響。（它們在真空中都有一樣的速度 299,177。）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。 (3)Infrared systems with range up to 3 km, limited to line of sight and limited by rain, fog, other airborne particles.（EDM 使用三種不同波長的波段：(1)微波系統(tǒng)【波段】，其測距范圍達(dá) 150km，波長 3cm，不受 限于視線范圍，也不受可見度的影響；(2)可見光波段，有效范圍 5km（小型儀器），可見光、激光， 其距離受可見度的影響會降低；(3)紅外線【Infrared】波段，測程 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 arebasically only two methods of measurement employed which may divide the instruments into twoclassification as electrooptical (light waves) and microwaves (radio waves) instruments.（盡管不同的EDM 用到不同的波長，基本上只有兩種測量方法在使用，可以將其【即 EDM】分為光電測距儀和 微波測距儀）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 thetime 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. （沿著要測的路徑發(fā)射 光波或微波，并測出發(fā)射和收到反射信號之間的時間間隔，或者是測出發(fā)射和接受反射信號之間的 相差【phase differences】，它們通過這種方法來運(yùn)行【function v.】）Modern EDM instruments are fully automatic to such an extent that, after the instruments, set up on onestation, emits a modulated light beam to a passive reflector set up on the other end of the line to bemeasured.（現(xiàn)代的 EDM 全自動化到這樣的程度【to such an extent that 到這樣的程度】，在一個站 點安置，需測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 需要按一個鍵，斜距就自動顯示出來。）At a given point there is only one vertical line.（在給定的一個點上只有一條垂線。）At any point there are an unlimited number of horizontal lines.（過任一點的水平線有無數(shù)【unlimited】 條。）The horizontal angle is used primarily to obtain relative direction to a survey control point, ortopographic detail points, or to points to be set out.（水平角主要【primarily】用來由聯(lián)測控制點獲得相對方向，或者地形測量碎部點、或者放樣點【or to points to be set out 應(yīng)該是 or points to be set out才對吧？？？direction to a survey control point、topographic detail points、points to be set out并列都是 obtain 的賓語。 and 177。.（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 radiuswith its center at the center of the earth.（天頂方向是一個術(shù)語，用來描述在天球【celestial sphere天球】上的點，天球是一個半徑無限【infinitely 無限地】大的球，其中心在地球中心。）It is thus between 0176。.（它的范圍是從 0 到 180 度）Obviously the zenith angle is equal to 90176。 to 360176。 that is, it is measured or designed to theright or to the left, or it is considered clockwise or counterclockwise.（在測的水平角有方向【direction、sense 這里都是方向的意思】，就是說【that is】它是向左測還是向右測，或者是說，順時針測還是逆時針測） In the above figure, the angle at A from B to C is clockwise and the angle from C to B is counterclockwise.（如上圖所示，在 A 點由 B 到 C 就是順時針角，而從 C 到 B 就是逆時針角）With the theodolite set up, centered, and leveled over at station A, then a simple horizontal anglemeasurement between surveying point B, A and C would be taken as follows:（經(jīng)緯儀在 A 點安置、對中、 整平后，在 B、A 和 C 測量點間的簡單的水平角測量可以按下列步驟進(jìn)行：）⑴Commencing on, say, “face left”, the target set at survey point B is carefully bisected and thereading on horizontal scale is 25176。（水平度盤制動螺旋松開，順時針轉(zhuǎn)動望遠(yuǎn)鏡至 C 點，水平度盤讀數(shù) 75 度） ⑶The horizontal angle is then the difference of the two directions, . (75176。) =50176。25176。）⑷Change face and observe point C on “face right”, and note the reading=255176