[Surveying] Quick Summary - Excerpt from Gaoshu Gang

Surveying Fundamentals

1.What is the concept of measurement？

测量学：Study the shape and size of the Earth,and the science of determining ground locations

包括测定和测设两部分：

测定：Use measuring instruments and tools,Obtain a series of measurement data through measurement and calculation,Or the topography of the earth's surface, a topographic map

测设：Plan and design the building on the drawings、The location of the structure is marked on the ground,作为施工的依据

2.Briefly describe the definition of level and its characteristics？

Static water form a gravitational equipotential surface,This surface is called the level surface

其特性：And everywhereThe direction of gravity is verticalcontinuous surface of

3.What is the geoid？

由平均Sea level instead of still water,formed by extending to the continent不规则closed surface of.

4.What are the datum planes and datum lines for measuring field work?？

大地水准面和铅垂线

5.Measuring calculation of reference plane and the reference line is in the industry？

参考椭球面和法线

6.What is absolute elevation（海拔）,What is relative elevation？

height from a point to the datum,The distance from a point to the geoid in the direction of the plumb line,usually called absolute elevation（海拔）->珠峰测量

distance from a level,relative elevation

7.What is the difference between the plane rectangular coordinate system used in measurement and the mathematical coordinate system？为什么？

答：In the plane Cartesian coordinate system used on the measurement,Let the north-south line through the origin be the ordinate axisX,与XThe direction perpendicular to the axis is the abscissaY,The axes divide the plane into4个象限,The order is clockwise,The coordinates of each point are specified from the origin up,向右为正

数学上：坐标系中,The north-south line through the origin is the ordinateY,与YThe direction perpendicular to the axis is the abscissa axisX,The axes divide the plane into4个象限,The order is in anti-clockwise order.

Because the measurement work stipulates that the direction of all straight lines is measured clockwise from the north end of the ordinate axis,After this transformation,neither change the mathematical formula,It is also convenient for the calculation of directions and coordinates in the measurement

 8.高斯投影的特点：

The angle on the ellipsoid surface is projected onto the plane after the angle is projected onto the plane,its angles are equal;

The central meridian is projected as a straight line with the same length,All other meridian projections are concave to the central meridian axis of symmetry

The equator is also projected as a straight line,and perpendicular to the central meridian,The projections of the remaining parallels are all symmetrical curves concave to the equator

 

 9.How the Gaussian projection is divided into bands

6°带：从0°子午线起,每隔经差6°Zone from west to east,依次用1~60编号.

带号Nwith the corresponding central meridianL0的关系是：L0=6N-3;N=[L/6°]+1;式中L——longitude of a place.

3°带：从1.5°子午线起,每隔经差3°Zone from west to east,依次用1~120编号,带号nwith the corresponding central meridianL'0的关系是：L'0=3°n;n=[L/3°+1]

 

 11.What are the names of the elevation system and the geodetic coordinate system that are used uniformly in our country?？Where is the origin of elevation in my country?？

The elevation system adopted uniformly in my country is called“1985年国家高程基准”

The geodetic coordinate system is called“2000国家大地坐标系”,The origin of elevation is atQingdao Guanxiang Mountain

12.1956年和1985What is the height datum respectively in country？

72.289m,72.260m

13.What is the significance of using the water plane instead of the level plane in the survey work?,what is the limit？

在半径为10km的范围内,When taking distance measurements,可以用水平面代替水准面,without having to account for the effect of the Earth's curvature on distance.（10Kilometers don't matter）

当面积P为100Km²时,When taking horizontal angle measurements,可以用水平面代替水准面,without having to account for the effect of the Earth's curvature on distance.（100Square kilometer doesn't matter）

用水平面代替水准面,The effect on the elevation is still very large

因此,再During the leveling,instant distance is short,The effect of Earth's curvature on elevation should also be taken into account

14.Regardless of any measurement work,The basic elements of in-situ measurements are：

距离、角度、高程,These quantities become positioning elements

It can be used to determine the plane position and three-dimensional space position of the point.

高程测量、Horizontal angle measurement and distance measurementis the basic content of surveying,

Elevation、Horizontal angle and distance are the basic work of measurement

15.To limit the propagation of errors,Usually measured in accordance with the：

“从整体到局部”,“先控制后碎部”,“The previous measurement work has not been checked and the next measurement work will not be carried out”的原则

高程测量

1.高程测量：Survey work for determining the elevation of ground points;

分为水准测量,三角高程测量,GPS高程测量,其中水准测量精度最高

2.水准测量：Use the horizontal line provided by the level to measure the height difference between two points on the ground

Calculate the elevation of the unknown point based on the elevation of the known point

when eye level,在A、BTwo points on the scale of read readingsa和b,则A、BThe height difference of the bright spot is equal to the difference between the two scale readings.即：hab=a-b.如果AThe elevation of the point is known,Bfor the point whose elevation is to be sought,则B点的高程为：Hb=Ha+hab,令HA+a=Hi,instrument line-of-sight elevation,high sight

 3.How to use the level：

粗平->瞄准->精平->读数

4.How parallax arises？To eliminate the parallax steps？

When observing the eyes move up and down slightly,If the ruler and reticle move relative to each other,i.e. the reading has changed,It means that there is parallax.

The reason for the parallax is that the plane of the target image and the plane of the reticle do not coincide,尺像没有落在十字丝平面上.

To eliminate the parallax steps：Telescope aimed at bright background,Rotate the eyepiece focusing screw（Turn the eye side first）,Make the crosshairs very clear;照准目标,Rotate the objective focusing screw（After the target side）,Make the target image very clear

5.水准路线：Route for levelling station observation.

分为：Echo level line,闭合水准路线,支水准路线.

闭合水准路线：starting and ending at the same known level环形水准路线;

 

Echo level line：start and endBetween two known high-level benchmarkslevel route;

 

支水准路线：from a known point,A route whose end is neither closed nor attached to another known benchmark

 6.There are calculation checks for leveling checks、Test station inspection、Results check.

Test station inspection通常有两种：1、change instrument high law;2、Double foot method（one side red,one side black）

 

角度测量

Distance measurement and straight line orientation

The Basics of Measurement Error

控制测量

Large scale digital mapping

测设