-
Topographic Surveying
地形测量
Introduction
序言
Topographic
surveys
are
made
to
determine
configuration
(relief)
of
the
earth's
surface and to locate nature and
cultural features on it .By means of various lines
and
conventional
symbols,topographic
maps
are
produced
from
survey
data.
A
topographic
map
is
a
large-scale
representation
of
a
portion
of
the
earth's
surface
showing
culture,relief,hydrography,and
perhaps
al
（
artificial
）
features
are
the
products
of
people,such
as
roads,trails,buildings,bridges,canals,a
nd
boundary and legends on maps
identify the features.
地形图地形测量用来确定地球表面的
形状，
定位自然
和人文地物。
通过各种
线条
和规定的符号，
就可以根据测量数据绘制地形图。
地形图是大比例表示部分地球
表面的人工建筑，救灾，水文，也许植被。
人文建筑是人类的产物，例如道路，
小径，建筑，桥梁，运河和边界线。地图上的名称和
图例是识别的特征。
Topographic maps
are made and used
by
engineers to
determine the
most
desirable
and
economical locations of
highways,railro
ads,canals,pipelines,transmission
lines,reservoirs,and other
facilities
；
by
geologists
to
investigate
mineral,oil,water,and
other
resources
；
by
foresters
to
locate fire-control roads and
towers
；
by architects in
housing and landscape
design
；
by
agriculturists
in
soil
conservation
work
；
and
by
archeologists,geographers,and
scientists in numerous fields.
< br>地形图是工程技术人员用来确定公路，铁路，管，管道，线路，水库，和其他设施最可取的
和经济的位置；地质学家用来研究矿物，油，水，和其他资源；林务员用来定位消防道路和
塔；建筑师用来设计住房和景观；农学家用来水土保持工作；考古学家，地理学家，许多领
域的科学家也都有运用。
A
planimetric
map
depicts
natural
and
natural
features
in
plan
only.A
hypsometric
map shows relief by conventions such as
contours,hachures,shading,and tinting.
一幅平面图仅仅在平面中描绘了人文建筑及其特征。一幅地形图则显示了地形，
例如等高
线、晕线、阴影和着色。
Methods for
Topographic Surveying
地形测量方法
Topographic
surveys
are
conducted
by
either
aerial
（
photogrammetric
）
or
ground
（
field
）
methods,and often a combination
of d equipment and procedures
available
today have made photogrammetry accurate and
economical
；
hence,almost
all topographic mapping projects
covering large areas now employ this method.
地形测绘是由空中（摄影测量
)
或地面方法完成的
，而且经常是两者的结合。现
今精良的设备和程序使得摄影测量很精确、
经济，
因此，
现在几乎所有覆盖大面
< br>积地区的地形测图工程都使用这种方法。
Ground
surveys are still frequently
used,however,especially for preparing large-scale
maps
of
small
areas.
Even
when
photogrammetry
is
utilized,ground
surveys
are
necessary
to
establish
control
and
to
field-
check
mapped
features
for
chapter
concentrates
on
ground
l
feild
procedures
for
locating
topographic
features,both horizontally and vertically,will be
described.
地面测量仍是经常使用的
,
然而
,
尤其是准备对大比例尺地图的小区域测图。
即使使用摄影测
量
,
地面测量为测量建
立控制和现场检查仍然是必要的
,
。本章集中于地面的方法。一
些行业
程序定位地形特征
,
在水平方向
和垂直方向
,
将被描述。
Control for Topographic Surveys
The first requirement of
any topographic survey is good control,whether the
survey is
done by ground or aerial l is
classified as either horizontal or vertical.
地形测量无论调查是用地面还是空中的方法，第一个要求都是良好的控制
,
。控
制是分为水平或垂直控制。
Horizontal control is provided by two
or more points on the ground,precisely fixed in
position
horizontally
by
distance
and
is
the
basis
for
map
scale
and
locating
topographic
ntal
control
is
usually
established
by
traversing,triangulation,
trilateration,or inertial and satellite
methods,and can be filled
in
photogrammetrically for
large areas.
平面控制由地面上的两个或多个点来确定，
精度由平面坐标位置的距离和方向来
固定。
地图比例尺
和地形特征是基本的要素。
平面控制通常由导线测量，
三角测<
/p>
量，三边测量，重力和卫星的方法和大区域的摄影测量来确定。
For small areas, horizontal control for
topographic work is generally established by
a
traverse,
although
a
single
line
may
suffice
in
some
cases.
Triangulation
and
trilateration
furnish
themost
economical
basic
control
for
surveys
extending
over
a
state
or
the
entire
United
States.
These
techniques
may,
however,
give
way
in
the
future
to
inertial
systems
and
Satellite
Doppler
receivers.
Monuments
of
the
state
plane coordinate
systems are excellent for all types of work ,but
unfortunately more
are needed in most areas
地形测
量中，
对于一些小面积的水平控制测量工作，
尽管在某些情况下
单导线
就可以满足精度要求，
但是通常还是用导线测量。
在一个州甚至整个美国，
三角
测量和三边测量
是最经济的基础控制测量方式。
无论怎样，
这些方技术给未来重
力系统和卫星多普勒接收器提供了方法。
州的平面坐标系统的埋
石对测量的各种
类型是有必要的，但是不幸的是大多数区域的埋石太少。
Specified
maximum
allowable
closure
errors
for
both
horizontal
and
vertical
control should be
established in advance of field work
在外
业之前，为了平面和高程控制的建立要指定最大的允许限差。
Vertical control is provided by bench
marks in or near the tract to be surveyed. .It
becomes the foundation for correctly
portraying relief on a map A vertical control net
is established by lines of levels
starting form and closing on bench marks.
Elevations
are
ascertained
for
all
traverse
hubs,
with
provision
in
some
cases
for
marks
set
nearby and out of the
way of construction. A lake surface is a
continuous turning point
or bench mark
and may sometimes be used .Even a gently flowing
stream may serve
as supplementary
control. Trigonometric and barometric leveling can
be employed to
extend vertical control
in rugged terrain, but the latter is less
accurate.
高程控制由测区的水准基点提供。
在地形
图上它成了正确描绘地形的基础。
一
个高程控制网由起止于水准
基点的水准路线构成。
导线中心确定了高程，
在一些
情况下，
规定要在建筑物附近或外面做标记。
湖的
表面是一个连续的转折点或标
记，
有时会使用。
即使轻轻流淌的河水可作为辅助控制。
在崎岖的地形三角高程
< br>和气压水准可以用来延长高程控制，但后者是不准确的。
Topographic
details
are
usually
built
upon
a
framework
of
traverse
hubs
whose