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[资料]角度测量
作者:成都新瑞测绘  来源:新瑞测绘  浏览:3299次  更新:2009/10/11 9:46:41

第一节 角度测量原理
   角度测量是确定地面点位的基本工作之一,经纬仪是最常用的测角仪器。角度测量分为水平角测量和竖直角测量。测量水平角的目的主要是用于求算地面点的平面位置,而竖直角测量则主要用于测定两点之间的高差,或将两点间的倾斜距离改化成水平距离。
   一、水平角测量原理
   地面上一点到两目标的方向线垂直投影到水平面上的夹角称为水平角。如图5—1-1所示,直线OA和OB的水平角是它们在水平面H上的投影O'A'、O'B'所构成的夹角β。β亦即包含OA和OB的两个竖面间的二面角∠A'O'B'。两竖面的交线为铅垂线,在此交线上任选一点O”,水平地放置一个顺时针刻划的圆度盘(0°—360°),O”为度盘中心。在度盘上方,过度盘直径方向装置一个可上下、左右转动的望远镜,当望远镜作上下转动时,其视线划出一个竖面,在同一竖面内视线无论处在什么位置,度盘上的读数不变;若保持度盘不动,使望远镜作左右转动,先后照准A、B两点,可得度盘的相应读数分别为a和b,OA、OB在水平面H上形成的水平角β为:
   β= b-a  (5-1-1)

二、竖直角测量原理
   竖直角是一点至目标方向线与水平线之间的夹角,用。表示,其角值为0°-±90°,当观测视线在水平线之上时,称为仰角,符号为正;当观测视线在水平线之下时,称为俯角,符号为负。如图5-1-1所示,OA视线的竖直角为仰角,OB视线的竖直角为俯角。
   若在望远镜的一侧装置一个可随望远镜一起旋转的竖直度盘(简称竖盘),望远镜安装在竖盘的直径方向上,当望远镜照准某目标时,借助一个固定不动的读数指标,可读得竖盘上的一个读数,此读数与望远镜水平时的竖盘读数之差,即为该直线的竖直角。可以写成:
   a=目标视线读数-水平视线读数  (5-1-2)或:
   a=水平视线读数-目标视线凑数  (5-1-3)
   由此可见,测量竖直角与测量水平角一样,其角值也是度盘上两个力’向读数之差。所不同的是两个方向中必须有一个是水平方向。不过任何注记形式的竖直度盘,当视线水平时,其竖盘读数应为定值,一般是90°的整数倍。
   第二节 DJ6型光学经纬仪
   经纬仪是测量角度的仪器,可用来观测水平角和竖直角,主要分光学经纬仪和电子经纬仪两种类型。按“野外—测回水平方向中误差”这一精度高低可分为若千等级,我国经纬仪系列标准划分为PJ07、DJ1、DJ2、DJ6及DJl5等。“D”和“J”分别是“大地测量”和“经纬仪”的汉语拼音第一个字母,数字代表该仪器一测回方向观测中误差的秒值。光学经纬仪按其精度不同,又可分为普通光学经纬仪和精密光学经纬仪两种。这里仅介绍DJ6型普通光学经纬仪。
   一、DJ6型光学经纬仪的构造
   各种光学经纬仪构造基本相同,如图5-2-1所示。图5-2-2是它的结构分解图。从图中可以看出,DJ6型光学经纬仪主要由照准部、水平度盘、基座三部分组成。

 

 

 

 

 

Section angle measuring principle
Angle measurement is to determine the basic work on the ground point and one of the most commonly used theodolite angle measuring apparatus. Angle measurement is divided into horizontal angle measurements and vertical angles were measured. The main purpose of measuring horizontal angle for Calculating the location of the ground plane points, while the vertical angle measurement is mainly used to measure the elevation difference between two points, or tilt the distance between two points changed into the horizontal distance.
First, horizontal angle measuring principle
Target on the ground that the direction of the two vertical lines projected onto the horizontal plane is called the angle between the horizontal angle. As shown in Figure 5-1-1, straight-line OA and OB of the horizontal angle of their projection on H in the horizontal plane O'A ', O'B' posed by the angle β. β which contains the OA and OB of the dihedral angle between the two vertical surfaces ∠ A'O'B '. Two vertical side cross-line plumb line, in this cross-line optional 1:00 O ", horizontally placed a circle depicts the dial clockwise (0 ° -360 °), O" as the dial center. In the dial at the top, over the direction of installation of a disc diameter can be up and down, turning left and right of the telescope, when the telescope to rotate up and down, his line of sight to draw a vertical surface, in the same vertical plane at the line of sight no matter what position on the dial readings of the same; if the retention plate fixed to the telescope to make turning left and right, has awarded A, B two points, the availability of the corresponding dial readings were a and b, OA, OB in the horizontal plane H formed on the horizontal angle β as follows:
β = b-a (5-1-1)


Second, the vertical angle measurement principle
Point to the target vertical angle is the direction of the angle between the line and the horizontal, with. That its angle value of 0 ° - ± 90 °, when the observation line of sight above the sea level, called the angle of elevation, sign is positive; when the observation line of sight below the horizon when the angle of depression is called, a negative sign. Figure 5-1-1 shows, OA line of sight of the vertical angle of elevation, OB line of sight of the vertical angle of depression angle.
If the telescope with the telescope side of the device with a vertical rotating dial (the vertical plate), a telescope installed in the vertical disc diameter direction, when the telescope awarded a goal, with a stationary indicator readings , was read on a vertical plate reading, this reading level with the telescope, the difference between the readings of the vertical plate shall be the vertical angle of the straight line. Can be written as:
a = target sight reading - the level of sight reading (5-1-2) or:
a = level of sight reading - make up the target line of sight (5-1-3)
Thus, measuring the vertical angle and horizontal angle measurements, like the angle value is also dial the last two forces' to the difference between the readings. The difference is that in both directions must have a horizontal direction. Note, however that any form of vertical dial, when the eye level, its vertical plate reading should be valued, is generally an integer multiple of 90 °.
Section DJ6 type optical theodolite
Theodolite instruments for measuring angles can be used to observe the horizontal angle and vertical angle, the main sub-optical theodolite and electronic theodolite types. Click "field - measurement error in the horizontal direction back to" This level of accuracy can be divided if the 1000 level, China's theodolite series of standards is divided into PJ07, DJ1, DJ2, DJ6 and DJl5 so. "D" and "J" are the "geodetic" and "theodolite" in Pinyin first letters, numbers, on behalf of the instrument back to the direction of a measuring error of the second value of observation. Optical Theodolite different according to their accuracy, can be divided into ordinary optical theodolite and two kinds of precision optical theodolite. Here describes only DJ6 type of common optical theodolite.
1, DJ6-type construction of optical theodolite
Various optical theodolite is basically the same structure, as shown in Figure 5-2-1. Figure 5-2-2 is its structural decomposition diagram. As can be seen from the figure, DJ6-type optical theodolite awarded mainly by the Ministry of the horizontal dial, the base of three parts.

 

 
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