4角度和方向测量

4角度和方向测量 Unit 4 Angle and Direction Measurement(角度和方向测量) Horizontal and vertical angles are fundamental measurements in surveying.(水平角和竖直角是测量的基本测量工作) It is necessary to be familiar with the meanings of certain basic terms before describing angle and direction measurement. (在描述角度和方向测量之前，有必要熟悉【be familiar with熟悉】几个【certain某些】基本术语的含义【meaning】) The terms discussed here have reference to the actual figure of the earth.(这里讨论的这些术语与地球的真实形状有关【have reference to与„„有关】) Basic Terms(基本术语) A vertical line at any point on the earth’s surface is the line that follows the direction of gravity at that point.(地球表面任一点的垂线是指这点上沿着重力的方向的线【可译为:地球表面任一点的垂线方向是过该点的重力方向】) It is the direction that a string will assume if a weight is attached at that point and the string is suspended freely at the point. (如果在这点上用线悬挂一个重物，当线自由【即无干扰】静止【suspended暂停的、悬浮的】时，这条线所呈现【assume呈现】的方向即重力方向。) At a given point there is only one vertical line.(在给定的一个点上只有一条垂线。) A horizontal line at a point is any line that is perpendicular to the vertical line at the point. (一点上的水平线是垂直【perpendicular垂直的】于过该点的垂线的直线。) At any point there are an unlimited number of horizontal lines.(过任一点的水平线有无数【unlimited】条。) A horizontal plane at a point is the plane that is perpendicular to the vertical line at the point.(过一点的水平面是垂直于过该点的垂线的平面) There is only one horizontal plane through a given point.(过给定的一个点只有一个水平面) A vertical plane at a point is any plane that contains the vertical line at the point.(过一点的竖直面是包含【contain】过该点的垂线的任一平面) There are an unlimited number of vertical planes at a given point.(过给定的一点有无数个竖直面) Horizontal Angle and Vertical Angle(水平角和竖直角) A horizontal angle is the angle formed in a horizontal plane by two intersecting vertical planes, or a horizontal angle between two lines is the angle between the projections of the lines onto a horizontal plane.(水平角是指在一个水平面内由两相交【intersect相交v.】的竖直面形成的角，或者说，两条线之间的水平角是这两条线在水平面上的投影线的夹角) For example, observations to different elevation points B and C from A will give the horizontal angle ?bac which is the angle between the projections of two lines (AB and AC) onto the horizontal plane.(例如，在A点观测不同高度的B和C点，其水平角?bac是由AB和AC两条线在水平面上的投影构成的) It follows that, although the points observed are at different elevations, it is always the horizontal angle and not the space angle that is measured (Figure 1).(由此得出结论【It follows that由此得出结论】，虽然被观测的点在不同的高度上，测出的总是水平角而不是空间角。) 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】用来由联测控制点获得相对方向，或者地形测量碎部点、或者放样点【or to points to be set out应该是or points to be set out才对吧,,,direction to a survey control point、topographic detail points、points to be set out并列都是obtain的宾语。】) A vertical angle is an angle measured in a vertical plane which is referenced to a horizontal line by plus (up) or minus (down) angles, or to a vertical line from the zenith direction.(竖直角是在一个竖直面内参考于【reference参考】水平线的正(仰)角或负(俯)角，或者相对于一个天顶方向的垂线的角) Plus and minus vertical angles are sometimes referred to as elevation or depression angles, respectively.(正负竖直角有时分别【respectively分别地】被称为仰角【elevation angle】或俯角【depression angle】) A vertical angle thus lies between 0? and ?90?.(竖直角位于【lie位于】0,90度之间) 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.(天顶方向是一个术语，用来描述在天球【celestial sphere天球】上的点，天球是一个半径无限 【infinitely无限地】大的球，其中心在地球中心。) The zenith is an angle measured in a vertical plane downward from an upward directed vertical line through the instrument.(天顶距是一个在竖直面内从一个过仪器的被定向为向上的竖直方向线 向下测量的角。) It is thus between 0? and 180?.(它的范围是从0到180度) Obviously the zenith angle is equal to 90? minus the vertical angles.(显然，天顶距等于90度减去竖直角) Vertical angles or zeniths are used in the correction of slope distance to the horizontal or in height determined.(竖直角或 天顶距用于斜距化平距的改正或者高程的测量) For the most part, the instrument used in the measurement of angles is called a transit or theodolite, although angles can be measured with clinometers, sextants (hydrographic surveys), or compasses.(在极大程度上【for the most part】，用 来测角的工具被称为经纬仪，虽然角度可以用倾斜仪【一种测量物体随时间的倾斜变化和铅垂线随时间变化的仪 器】、六分仪(用于海道测量)、或罗盘仪来测) The theodolite contains a horizontal and vertical circles of either glass or silver.(经纬仪有一个玻璃的或镀银的水平度 盘和竖直度盘) The horizontal and vertical circles of theodolite can be linked to circular protractors graduated from 0? to 360? in a clockwise manner set in horizontal and vertical plane.(经纬仪的水平度盘和竖直度盘与顺时针刻【graduate】了0 到360度刻划的圆分度器【circular protractor】相连) The horizontal circle is used when measuring or laying off horizontal angles and the vertical circle is used to measure or lay off vertical angles or zenith angles.(测或拨水平角时用水平度盘，测或拨竖直角或天顶距时用竖直度盘【lay off 翻译为拨、放样的意思】) Usually the units of angular measurement employed in practice are degrees, minutes, and seconds, the sexagesimal system.(通常角度测量法【angular measurement角度测量法】使用的单位是六十进制【sexagesimal六十进制的】 的度、分、秒) Angle Measurement (角度测量) A horizontal angle in surveying has a direction or sense; that is, it is measured or designed to the right or to the left, or it is considered clockwise or counterclockwise.(在测的水平角有方向【direction、sense这里都是方向的意思】，就是 说【that is】它是向左测还是向右测，或者是说，顺时针测还是逆时针测) In the above figure, the angle at A from B to C is clockwise and the angle from C to B is counterclockwise.(如上图所 示，在A点由B到C就是顺时针角，而从C到B就是逆时针角) With the theodolite set up, centered, and leveled over at station A, then a simple horizontal angle measurement between surveying point B, A and C would be taken as follows:(经纬仪在A点安置、对中、整平后，在B、A和C测量点 间的简单的水平角测量可以按下列步骤进行:) ?Commencing on, say, “face left”, the target set at survey point B is carefully bisected and the reading on horizontal scale is 25?.(着手，说【示意】，“盘左”，【用竖丝】将B点的目标仔细分中，水平度盘读数为25度) ?The upper plate clamp is released and telescope is turned clockwise to survey point C. The reading on horizontal circle is 75?(水平度盘制动螺旋松开，顺时针转动望远镜至C点，水平度盘读数75度) ?The horizontal angle is then the difference of the two directions, i.e. (75?-25?) =50?(水平角就是两个方向值的 差值，即， (75?-25?) =50?) ?Change face and observe point C on “face right”, and note the reading=255?(换度盘方向至盘右并照准C点，记 下读数为255度) ?Release upper plate and swing counterclockwise to point B and note the reading =205?(松开水平度盘，逆时针旋 转【swing】至B点并记下读数为205度) ?The reading or the direction must be subtracted in the same order as 255?-205?=50?(读数或者说是方向值按同 样的法则【order】相减，255?-205?=50?) ?The mean of two values would be accepted if they are in acceptable agreement.(如果两个减出来的值的一致性是可 接受的【在误差范围之内】，取两个值的平均值。) Modern electronic digital theodolites contain circular encoders that sense the rotations of the spindles and the telescope, convert these rotations into horizontal and vertical (or zenith) angles electronically, and display the value of the angles on liquid crystal displays (LCDs) or light-emitting diode displays (LEDs).(现代的电子数字经纬仪包含编码【encoder编码】度盘，能够感知轴【spindle轴、纺锤】和望远镜的旋转，并使之电子地转换为水平角度和竖直角度，并在液晶显示器【LCDs】或发光二极管显示器【LEDs】上显示出来) These readouts can be recorded in a conventional field book or can be stored in a data collector for future printout or computation.(这些显示可以被一个传统的【conventional】野外电子手簿或数据收集器【存储卡】，以便日后打印或计算) The instrument contains a pendulum compensator or some other provision for indexing the vertical circle readings to an absolute vertical direction. (这种仪器具有一个悬挂【pendulum钟摆】补偿器【compensator】或其它装置，使竖盘指标【indexing指标】读数指向一个绝对竖直方向) The circle can be set to zero readings by a simple press of a button or initialized to any value on the instrument.(这个度盘可以通过简单的按一个键就将其置零，或初始化成任一值) Azimuth is the horizontal angle measured in a clockwise direction from the plane of the meridian, which is a line on the mean surface of the earth joining the north and south poles. (方位角是从子午面【plane of the meridian 】起算按顺时针旋转的角，子午线是在地球平均表面连接北极与南极的线) Azimuth ranges in magnitude from 0? to 360?, values in excess of 360?, which are sometimes encountered in computations, are simply reduced by 360? before final listing.(方位角的取值范围从0度到360度，超过360的值――有时会在计算时遇到【encounter遭遇】，只需减去360度即可) Bearing is the traditional way of stating the orientation of the line.(方向角是一种传统的描述【state说明】直线方向【orientation方向、方位】的) It is actually the angle measured from the north or south.(实际上，它是从南或北方向开始量测的角) The bearing, which can be measured clockwise or counterclockwise from the north or south end of the meridian, is always accompanied by letters that locate the quadrant in which the line falls.(方向角可以从子午线【meridian】北端或南端以顺时针或逆时针量测，总是伴【accompany】以字母，用来标明【locate定位】直线所落在的象限【quadrant】) For example, bearing N32W indicates a line trending 32? west of the north. (例如:方向角N32W代表【indicate】一条直线从北方向转向【trend通向、转向】西方向32度) It is equal to an azimuth of 328?.(它等于方位角328度) Bearing S12W indicates a line trending 12? west of the south. (方向角S12W代表一条直线从南方向转向西方向12度) It is equal to an azimuth of 192?.(它等于方位角192度) It is important to state that the bearing and azimuth are respect to true north.(需要重点说明的是，方向角和方位角所用的【respect关于、有关、尊重】是真北方向。)