第三测绘工程专业英语课文全部翻译

Section 2 The Reliability of a Survey and Errors

测量误差的可靠性

Since every technique of measurement is subject to unavoidable error, surveyors must be aware

of

all

sources

and

types

of

error

and

how

they

combine.

If

the

accuracy

of

a

measurement

is

defined

as the nearness of that value to its true value (a quantity we can never know) then a surveyor

must ensure that the techniques he chooses will produce a result that is sufficiently accurate.

He must know, therefore, how accurate he needs to be, how to achieve this accuracy and how to

check that the required accuracy has been achieved.

< /p>

由于每个测量技术是不可避免的误差，测量员必须知道的所有误差的来源和类型，以及它们 是如何结合。

如果测量的准确性，其真正的值（我们可以永远不知道的数量）的接近程度 ，该值被定义为，然后测量员

必须确保他选择的技术将产生一个结果，是足够精确的。因 此，他必须知道他需要的精度如何，如何实现

这一目标的准确性和如何检查所要求的精度 已经达到。

Accuracy required

When

surveying

to

produce

a

plan,

the

accuracy

required

is

defined

by

the

scale

of

the

plot,

since

there

should

be

no

plottable

error

in

the

survey

data.

A

good

draughtsman

can

plot

a

length

to within 0.25 mm and so, if a plan of an area is required at a scale of 1/1000, i.e., 1 mm on

the plan represents 1 m on the ground, the smallest plottable distance is 0.25 m. Thus, for a

survey at 1/1000 scale, all the measurements must be taken such that the relative positions of

any point with respect to any other must be determined to 0.25 m or better.

当测量一个平面时

,

< br>精度通常是根据展图比例决定的，因为在绘图中不能有测量误差。一个好的绘图

员 可以在大约

0.25

毫米的范围内画图，假如一个地区的图纸比 例尺要求是

1/1000

，即

1

毫米图上距离代

表

1

米实地距离，那么最小的测距应该是

0.25

米。因此，对于< /p>

1/1000

比例尺的测量，所有测量必须保证

< br>任意一点与其他任一点的相对位置不得大于

0.25

米。

The specifications of surveys for other purposes such as engineering works or property

boundary definition might well be determined by engineering tolerances or legal standards.

基于测量规范可 能被用于其他目的，如工程测量或财产边界的测量将由工程限差和合法的基准决定。

Achieving the specification

To ensure that the specification is achieved the equipment and methods must be chosen such

that, not

only will they collect

the right sort of data, i.e., the correct

combination

of

angles

and distances, but that the data will be to the required accuracy. There are several types of

error that occur and a knowledge of their importance and characteristics is essential in the

understanding of the limitations of the techniques of measurement. The salient features will be

stated now but further information is given in later chapters.

为了确保测量符合规范，仪器和数据应按照以下要求进行，并 不是只是得到正确的数据，即更正角和边的

关系，从而得到的数据满足精度的要求。在测 量中有几种类型的误差，掌握它们的重要性和特性对于理解

测量技术的限差是必不可少的 。本章主要讲解这些误差的主要特征，后面的章节将提供进一步的阐述。

Mistakes

粗差

Blunders or mistakes are often inaccurately referred to as gross errors. Miscounting the

number of tape lengths when measuring a long distance or transposing numbers when booking are

two very simple, but all too common, examples of mistakes. These types of mistakes can occur at

any stage of a survey, when observing, booking, computing or plotting, and they would obviously

have a very damaging effect on the results if left uncorrected. However, by following strictly

a well-planned observing procedure it is possible to reduce the number that occur and then

independent

checks

at

each

stage

should

show

up

those

that

have

been

made.

In

practice,

none

should

ever go undetected and uncorrected.

错误经常不准确的理解为粗差。

当测 量

很长一段距离时，

读错尺的读数或记录两个简单的数时颠倒它 们的

位置，这些都是很常见的错误例子。这些类型的误差可以发生在测量任何阶段，当观 测，记录，计算和绘

图，如果不纠正这些错误，他们在结果上显然有一个非常有害的影响 。但是，通过严格周详的观测过程，

可能杜绝这些错误的产生，然后在每个阶段应独立检 测可以是这些错误显现出来。在实践中，没有不可发

现和不可纠正的粗差。

Systematic errors

系统误差

Systematic errors arise from sources which act in a similar manner on observations. The method

of

measurement,

the

instruments

used

and

the

physical

conditions

at

the

time

of

measurement

must

all

be

considered

in

this

respect.

Expansion

of

steel

tapes,

frequency

changes

in

electromagnetic

distance

measuring

(EDM)

instruments

and

collimation

in

a

level

are

just

a

few

examples

of

possible

sources of systematic errors.

系统误差的来源于以 相同的观测方式。测量时要考虑这些方面，测量的方法、测量仪器和外界环境。钢尺

的膨 胀，电磁测距仪的频率变化和水准仪的照准情况都是系统误差的可能来源。

These

errors

are

of

vital

importance

in

activities

which

consist

of

adding

together

a

succession

of individual observations (see sections on leveling and traversing). If all the individual

measurements contain the same type of systematic error, which by their nature always act in the

same direction, then the total effect is the sum of them all.

< br>这些误差在由一系列独立观测（参见水准测量和导线测量部分）累加在一起组成的测量值中极为重要，如< /p>

果所有的独立测量包含相同类型的系统误差，且这些系统误差总是表现出相同的性质，那么 总影响是所有

这些的总和。

It must be ensured that measurements are as accurate as required by removing the effects

of

all

factors

that,

if

neglected,

would

result

in

a

significant

error.

The

errors

caused

by

some

factors can be eliminated with the correct observing procedure and others countered by applying

corrections. Systematic errors are not revealed by taking the same measurement again with the

same instruments. The only way to check adequately for systematic error is to remeasure the

quantity by an entirely different method using different instruments.

通过消除所有因素的影响确保精度满足要求。如何忽略这些因素将会导致重大的错误。通过正确 的观测程

序以及纠正计算可以消除误差。通过同样的仪器用同样的方法测量是检测不出系 统误差的。唯一能充分检

测系统误差就是重测这些量通过使用完全不同的测量方法和测量 仪器。

Random errors

Random errors are really all those discrepancies remaining once the blunders and systematic

errors have been removed. Even if a quantity is measured many times with the same instrument in

the

same

way,

and

if

all

sources

of

systematic

error

have

been

removed,

it

is

still

highly

unlikely

that

all

results

will

be

identical.

The

differences,

caused

mainly

by

limitations

of

instruments

and observers, are random errors.

随机误差事

实上是除去粗差和系统误差后。

即使测定数量很多次以同样的方式与相同 的仪器，

和已被删除，

如果所有系统误差的来源，它仍然是极不 可能的，所有的结果将是相同的。的差异，主要仪器和观察员的

限制造成的，是随机的误 差。

It is found in practice that these errors, although called random, have the following

characteristics:

(1) small errors occur more frequently than large ones

(2) positive and negative errors are equally likely to occur

(3) very large errors seldom occur.

在实践中发现，这些误差，虽然称为随机的，具有以下特点：

（

1

）小误差发生的频率比大

（

2

）正面和负面的 误差发生的可能性相同

（

3

）非常大的误差很少发生。

These

characteristics

are

typical

of

errors

which

are

normally

distributed

and

it

is

assumed

that

we

can

use the

mathematical

theory

based

on

the normal distribution to

deal

with the

errors

met with in surveying.

正态分布是这些误差典型的特点是，我们可以用基于正态分布的数学理论来处理这些测量中的误差 。

Understanding the errors that limit the accuracy of the measurement techniques is but one

step to ensuring specifications are achieved, as will be seen when the methods of survey are

described:

了解限定测量方法精度的误差仅仅是确保满足测量规范的一步，按照如下的测量方法进行：< /p>

(a)

The

survey

area

is

always

totally

covered

with

the

simplest

possible

framework

of

high

quality

measurements. If the rest of the survey work is carried out within this control the possible

damaging

accumulation

of

errors

can

be

contained.

This

is

often

termed

'working

from

the

whole

to the part',

（

a

< br>）测区总是由高精度的测量框架所覆盖。

如果剩下的测量工作在这个控制网内进行 的话，

累积误差就可

以得到有效地控制。这通常被称为“从整体 到的部分的工作，

(b) Observing

procedures

are designed

so

that

(i) most mistakes

that

occur are

discovered

immediately and (ii) possible sources of systematic errors eliminated.

（

b

）观 测程序设计，

（ⅰ）大多数误差及时被发现，

（

ii

）系统误差得到有效地控制。

(c) Additional, or redundant, observations are taken so that all data can be checked for the

mistakes, systematic errors and random errors that do occur. For example, the three angles

of

a

triangle

would

be

observed

although

only

two

are

required

to

define

the

shape.

The

third

angle could be deduced but, when measured, acts as a check.

（

c

）多余的观测是用 来检测粗差、系统误差、偶然误差的。例如，一个三角形观测中，只要观测两个

角就能决 定其形状。但第三角度的观测是用来检核的。

(d) Many quantities are observed several times. These repeated measurements and the observation

of redundant data serve both as checks and to improve on the precision of the final results.

（

d

）许多数据 需要多次观测。重复观测是用来检核并提高最终精度的。

Checking the survey

Even with all the checking procedures the surveyor employs, errors can still occur in the

finished plan and for this reason final independent checks are required. For simple work this

would involve inspecting the final plan in the field and comparing some measurements scaled off

the plan with their equivalents on the ground.

虽然测量员按照检核步骤进 行检核，但是误差仍然可以出现在最后的平面图中所以最后还需要进行独立检

核。对于这 项简单的测量工作，需要到野外进行最后的平面图纸的检核和图纸距离放到实地进行比对。

Angle and Direction Measurement

角度和方向测量

Horizontaland vertical angles are fundamental measurements in is necessary to be

familiar

withthe

meanings

of

certain

basic

terms

before

describing

angle

and

direction

measurement.

The terms discussed here have reference to the actual figure of the earth.

水平角和竖直角是测量的基本测量工作

< br>,

在描述角度和方向测量之前，有必要熟悉几个基本术语的含义

< br>,

这

里讨论的这些术语与地球的真实形状有关

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. 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. At a given point there is only one

vertical

line.A

horizontal

line

at

a

point

is

any

line

that

is

perpendicular

to

the

vertical

line

at the point. At any point there are an unlimited number of horizontal lines.A horizontal plane

at a point is the plane that is perpendicular to the vertical line at the is only

one

horizontal

plane

through

a

given

point.

A

vertical

plane

at

a

point

is

any

plane

that

contains

the

vertical

line

at

the

point.

There

are

an

unlimited

number

of

vertical

planes

at

a

given

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

,

如果在这点上用线悬挂一个重物，

当线自由静止时，

这条线所呈现的方向即重力方向。在给定的一个点上只有一条垂线 。一点上的水平线是垂直于过该点的垂

线的直线。

过任一点的水 平线有无数条。

过一点的水平面是垂直于过该点的垂线的平面

,

过给定的一个点只

有一个水平面

.

过一点的竖直面是包含过该点的垂线的任一平面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. 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. 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 .The

horizontal angle is used primarily to obtain relative direction to a survey control point, or

topographic detail points, or points to be set out. 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.

Plus

and

minus

vertical

angles

are

sometimes

referred

to as elevation or depression angles respectively. A vertical angle thus lies between 0

°

and

±

90

°

.Zeni th

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. The zenith is an angle measured in a

vertical

plane

downward

from

an

upward

directed

vertical

line

through

the

instrument.

It

is

thus

between 0

°

and 180

°

.

水平角是指在一个水平面 内由两相交的竖直面形成的角，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

.

例如，在

A

点观测不同高度的

B

和

C< /p>

点，其水平角∠

bac

是由

AB

和

AC

两条线在水平< /p>

面上的投影构成的

.

由此得出结论结论，

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。

水平角主要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

,

竖直角是在一个 竖直面内

参考于水平线的正（仰）角或负（俯）角，或者相对于一个天顶方向的垂线的角

.

正负竖直角有时分别被称

为仰角或俯 角

.

Obviously

the

zenith

angle

is

equal

to

90

°

minus

the

vertical

angles.

Vertical

angles

or

zeniths

are used in the correction of slope distance to the horizontal or in height determined. 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.

The

theodolite

contains

a

horizontal

and

vertical

circles

of

either

glass

or

silver.

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. 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.

Usually

the

units

of

angular

measurement

employed

in

practice

are degrees, minutes, and seconds, the sexagesimal system.

竖直角位于

0

～< /p>

90

度之间

.

天 顶方向是一个术语，用来描述在天球上的点，

天球是一个半径无限大的球，

其

中心在地球中心。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。它

的范围是从

0

到

180

度。显然，天顶距等于

9 0

度减去竖直角

.

竖直角或天顶距用于 斜距化平距的改正或者

高程的测量

.

在 极大程度上，用来测角的工具被称为经纬仪，虽然角度可以用倾斜仪、六分仪、或罗盘仪来

测，经纬仪有一个玻璃的或镀银的水平度盘和竖直度盘

.

经纬 仪的水平度盘和竖直度盘与顺时针刻了

0

到

360

度刻划的圆分度器相连。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，通常角

度测量法使用的单位是六十进制的度、分、秒。

< br>

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.

In

the

above

figure,

the angle at A from B to C is clockwise and the angle from C to B is counterclockwise. 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:

在测的水平角有方向，就是说它是向左测还是向右测，或者是说，顺 时针测还是逆时针测

.

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，经纬仪在

A

点安置、对中、整平后，在

B

、

A< /p>

和

C

测量点间的简单的水平角测量可以按 下列步骤进行：

⑴

Commencing on , say,

“

face left

”

, the target set at survey point B is carefully bisected

and the reading on horizontal scale is 25

°

.

⑵

The upper plate clamp is released and telescope is turned clockwise to survey point C. The

reading on horizontal circle is 75

°

⑶

The horizontal angle is then the difference of the two directions, i.e. (7 5

°

-25

°

) =50

°

⑴说示意，