# Arrangement of geodetic knowledge points

2022-05-15 07:28:07

Chapter one
Geodetic definition
In a broad sense ： Geodesy is at a certain time - In spatial reference system , The science of Surveying and mapping the earth and other planetary bodies .
narrow sense ： Geodesy is the science of Surveying and describing the earth's surface . Including measuring the shape and size of the earth , Determine the geometric position of ground points , Determine the earth's gravity field , And those measurements on the earth that must take into account the curvature of the earth .

The most basic task of geodesy is to measure and describe the earth and monitor its changes , Provide human activities with spatial information about planetary bodies such as the earth .
P1 P4 P6( Understand several stages 、 Understanding the outlook )
The position and function of Geodesy ：
1、 Geodesy plays an important guarantee role in the construction of national economy and social development
2、 Geodesy in disaster prevention 、 disaster reduction 、 Disaster relief and environmental monitoring 、 It plays a unique role in evaluation and protection
3、 Geodesy is an important guarantee for the development of space technology and national defense construction
4、 The position of Geodesy in contemporary geoscience research is becoming more and more important
5、 Geodesy is a branch of Surveying and mapping （ This includes geodesy 、 Engineering survey 、 Ocean Survey 、 Mine survey 、 Aerial photogrammetry and remote sensing 、 Cartography and GIS, etc ） Basic science

There are three basic branches of modern geodesy ： Geometric geodesy 、 Physical geodesy 、 Space geodesy
Chapter two
Kepler's laws of motion of the three planets ：
1、 The orbit of the planet is an ellipse , The sun is at a focal point of the ellipse
2、 In planetary motion , The area swept in unit time is equal to that of the sun
3、 The ratio of the square of the period of planetary motion around the orbit to the cubic of the long half axis of the orbit is constant

The change in the direction of the earth's axis relative to space （ Precession and nutation ）（ Short answer questions ）
The relative position change of the earth axis relative to the internal structure of the earth body （ Pole shift ）

Epoch ： For satellite systems or astronomy , The corresponding moment of an event .

A description of time , One dimensional time axis can be used , There is a time origin 、 Unit of measure （ scale ） Two elements , The origin can be specified as needed , The unit of measurement is in the form of time and time interval .

Any periodic motion , If the following three requirements are met , It can be used as a method of measuring time ：
1、 Motion is continuous
2、 The period of motion has sufficient stability
3、 Motion is observable

Multiple time systems
Based on the rotation of the earth ： Stellar time and universal time
Based on the earth's revolution ： In the almanac → The centroid mechanics of the solar system 、 When the earth's center of mass mechanics
Based on the motion characteristics of atoms in matter ： Atomic time
Coordinated universal time （P23）
Geodetic datum ： Establishing geodetic datum is to determine the parameters and orientation of rotating ellipsoid （ The axis of rotation of the ellipsoid is parallel to the axis of rotation of the earth , The initial meridional plane of the ellipsoid is parallel to the initial meridional plane of the earth ） And positioning （ The relative relationship between the center of the rotating ellipsoid and the center of the earth ）.

Celestial sphere ： Centered on the center of mass of the earth , An imaginary sphere with a radius of infinity .
The celestial axis 、 Celestial pole 、 The equatorial plane of the celestial sphere 、 celestial equator 、 Time circle 、 Ecliptic 、 Huangji 、 Spring equinox

Geodetic reference system
1、 Coordinate reference system ： Celestial coordinate system and earth coordinate system （ Geodetic coordinate system (P26 I can draw )、 Space rectangular coordinate system ）.
2、 Elevation reference system ： It's high 、 Normal high
3、 Gravity reference system

Geodetic datum → Geodetic reference system → Geodetic reference frame （ coordinate 、 Altitude 、 gravity ）（ The relationship between the three P27）

Ellipsoid positioning and orientation
A rotating ellipsoid is a body formed by the rotation of an ellipse around its minor axis , By selecting the long half axis and oblateness of the ellipse , You can get a rotating ellipsoid very close to the earth , The rotating ellipsoid is a mathematical surface with regular shape , On which rigorous calculations can be made , And the calculated elements （ Such as length and angle ） Very close to the corresponding elements on the geoid , This kind of ellipsoid used to represent the shape of the earth is called the earth ellipsoid , It is the reference datum of the earth coordinate system .

Ellipsoid positioning ： Locate the center of the ellipsoid （ Local positioning and geocentric positioning ）.

Ellipsoidal orientation ： Determine the direction of the axis of rotation of the ellipsoid .
Meet the conditions （1） The minor axis of the ellipsoid is parallel to the earth's axis of rotation （2） The earth starting meridian plane is parallel to the astronomical starting meridian plane

Reference ellipsoid ： With definite parameters （ Long half axis a Flattening rate α）, After local positioning and orientation , The earth ellipsoid that best fits the geoid of a certain area .
Total earth ellipsoid ： In addition to satisfying the geocentric positioning and double parallel conditions , When determining the parameters of the ellipsoid, it can make it the earth's ellipsoid which is the closest to the earth in the world .

Reference center coordinate system ( Different from geocentric coordinates P31)： The origin coincides with the center of the reference ellipsoid .（ Based on the reference ellipsoid ）
The geocentric coordinate system ： The origin coincides with the center of mass of the earth .（ Based on the total earth ellipsoid ）

The geocentric geodetic coordinate system ： The center of the earth's ellipsoid coincides with the earth's center of mass , Ellipsoid and geoid are in the best agreement in the world , The minor axis of the ellipsoid coincides with the earth's rotation axis （ Cross the earth's center of mass and point to the north pole ）, The geodetic latitude is the angle between the normal of the ellipsoid passing through the ground point and the equatorial plane of the ellipsoid , The earth longitude is the angle between the ellipsoid meridian passing through the ground store and the great earth meridian in Greenwich , The geodetic height is the distance from the ground point along the ellipsoidal normal to the ellipsoidal surface .

The establishment method of geocentric and geostationary coordinate system (P37)： direct method （ Get the coordinates directly ） And indirect method （ Find the conversion parameters ）
World geodetic coordinate system （WGS-84,CGCS2000（P40））
International Earth reference system （ITRS） International Earth reference framework （ITRE）（P39）

Angle Euler ： The rotation angle of two rectangular coordinate systems .（ How did the rotation matrix come from ？P44）
For existing rotations 、 The zoom , Coordinate conversion of two space rectangular coordinate systems with translation , There is 3 Translation parameters ,3 Two rotation parameters and 1 A scale change parameter , There are 7 Parameters .
For the conversion of different geodetic coordinate systems （ Know the process P47）, It also includes 2 A variation parameter of earth ellipsoid element , common 9 Conversion parameters .
The third chapter
P50 P55 understand
Basic parameters of the earth （3.1.3 P57）
In Geodesy , The significance of the gravity field outside the earth ：
1、 The gravity field outside the earth is the reference frame of most observations in geodesy , therefore , In order to reduce the observation to the reference system defined by geometry , You have to know the gravitational field
2、 If the distribution of ground gravity value is known , It can be combined with other observations in geodesy , To determine the shape of the earth's surface
3、 For elevation survey , The most important reference plane —— Geoid , That is, the most ideal ocean surface is a level in the gravity field
4、 Through the in-depth analysis of the earth's external gravity field ,, People can get information about the structure and properties of the earth's interior , Therefore, the corresponding gravity field parameters are applied , Geodesy has become an auxiliary science of geophysics
5、 The gravity field outside the earth is the theoretical basis of modern space exploration technology , Especially for the launch and control of space detectors , It plays an important role in lunar geodesy and deep space geodesy of other planets in the solar system

gravity ： The resultant force of the lunar calendar and centrifugal force （ Basically determined by gravity ）
The centrifugal force reaches... At the equator MAX, Its value is higher than that of the earth's gravity 1/200 lower .
There are two levels of gravity MAX, The equator MIN, Only point to the center of the earth at two levels .

Gravitational potential and centrifugal force potential （ How did it come from ？P59）
Gravitational potential （ How to express ?P62）
A line that coincides with the direction of gravity is called a plumb line .

Normal gravitational potential ： A function is simple 、 The auxiliary gravitational potential of the approximate value of the earth's gravitational potential that can be calculated directly without involving the earth's shape and density （ Why introduce ？P64）
P70 The earth's normal gravitational potential
Normal gravity formula （ expression Symbolic meaning P71）
Further understanding of the normal gravitational potential constant P74
Normal ellipsoid and horizontal ellipsoid , The relationship between the total earth ellipsoid and the reference ellipsoid P75
Can draw and explain Positive altitude system P76 Normal high system P77

Force is high （ Concept 、 difference P80）

3.3.5 National height datum
Geoid ： The surface of the sea when the ocean is supposed to be completely at rest and in equilibrium , And extends below the continental surface .（ Average sea surface ）
P82 Leveling origin
P82 1956 Yellow Sea elevation system
P83 1985 National height datum

Vertical deviation ： The vector of gravity at a point on the ground g And the normal vector on the corresponding ellipsoid n The Angle between .
Determine the method ： Astrogeodetic method 、 Gravity measurement method 、 Astronomical gravimetry 、GPS Method .

Determine the geoid difference （P86） Several ways to ： Earth gravity field model method 、 Stokes method 、 Satellite radio altimetry method 、GPS Elevation fitting method 、 Least squares collocation method .

The basic method of determining the shape of the earth ： Astrogeodetic method 、 Gravity measurement method 、 Space geodetic method （ understand ）

Chapter four （ drawing ）
The basic geometric parameters of the earth's ellipsoid （P99 chart 4-1）：2 A length element 、3 A flat element

Geodetic coordinate system P（L,B,h）P101
Space rectangular coordinate system P（X,Y,Z）P102
Meridian rectangular coordinate system P（L,x,y）P102
Geodetic polar coordinate system P（S,A）P103

The relationship between coordinate systems （P103-104）( Comprehensiveness 、 a key )

Normal section ： Through any point on the ellipsoid, a normal perpendicular to the ellipsoid can be made , The plane containing this normal .
French intercept （ Normal arc cutting ）： Intersection of normal section and ellipsoid .

Radius of curvature of meridional circle （P108 P109 surface 4-2）
Radius of curvature of the unitary circle （P109 P110 surface 4-3）

Ground wire （ Definition 、 nature 、 Relative normal intercept P121-123）

The reference ellipsoid is the datum plane for measurement and calculation . But all kinds of measurements in the field are carried out on the ground , The observed datum line is not the normal of the ellipsoid corresponding to each point , But the vertical line of each point , There is a vertical deviation between the vertical line of each point and the normal line .
The observation results cannot be processed directly on the ground , Instead, ground observation elements should be （ Distance, etc ） Reduce to ellipsoid . There are two basic requirements in the reduction （1、 Based on the normal of the ellipsoid （2、 The ground observation elements are transformed into the corresponding elements of the geodesic on the ellipsoid .

Reduce the horizontal direction to the ellipsoid , Including correction of vertical deviation 、 Elevation difference correction 、 Section error correction （ Why? ？P125）

Earth elements ： The geodetic longitude of a point on an ellipsoid L、 Latitude of the earth B, The length of the earth wire between two points S Extremely positive 、 Anti large local potential angle A12,A21
Positive solution of Earth Theme ： It is known that P1 Geodetic coordinates of points L1 B1,P1 to P2 The length of the main ground wire S And its large local potential angle A12, Calculation P2 Geodetic coordinates of points L2 B2 And ground wire S stay P2 The inverse potential angle of the point A21.
Earth Theme inverse solution ： It is known that P1 Geodetic coordinates of points L1 B1,P2 Geodetic coordinates of points L2 B2, Calculation P1 to P2 The length of the earth line S Extremely positive 、 Anti azimuth angle A12、A21.

The essence of the positive and negative solutions of the Earth Theme ： In terms of meaning , Study the mutual transformation between great polar coordinates and geodetic coordinates .

Map mathematical projection ： Put the elements on the ellipsoid （ Including coordinates 、 Azimuth and distance ） Project onto a plane according to certain mathematical rules .
Map projection ： Study the elements on the ellipsoid （ Including coordinates 、 Azimuth and distance ） A specialized subject projected onto a plane according to certain mathematical rules .

Measure the deformation of map projection ：1） Length ratio 2） Main direction and deformation ellipse

Type of projection deformation 1） Length deformation 2） Directional deformation 3） Angular deformation 4） Area deformation

Map projection classification
1、 Classification according to deformation properties ： Isometric projection 、 Isometric projection 、 Arbitrary projection
2、 Classified according to the projection shape of longitude and latitude network ： Azimuth projection 、 Conic projection 、 Cylinder （ Or an elliptical column ） Projection
3、 Classified according to the relative position relationship between the projection plane and the original plane ： Orthaxial projection 、 Transverse projection 、 Oblique projection 、 Cut the cylinder 、 Cut cone projection

Gauss plane rectangular coordinate system （ How did it come from ？P158）
P160 chart 4-40
The fifth chapter
Basic principles of establishing national plane Geodetic Control Network ：
1、 The geodetic control network shall be arranged in grades 、 Step by step control
2、 The geodetic control network shall have sufficient accuracy
3、 The geodetic control network should have a certain density
4、 The geodetic control network shall have unified technical specifications and requirements

Layout principle of national elevation control network ：
1、 From high to low 、 Step by step control
2、 The distribution of benchmarks shall meet a certain density
3、 The leveling reaches sufficient accuracy
4、 The first-class leveling network shall be retested regularly

These are the knowledge points I sorted out before , You can refer to , But I don't have it all , A lot of understanding, I marked the page and didn't write （ Because it's complicated ）, Now let me tell you what he emphasized in class . The following are important ！！！
1、 There are three basic branches of modern geodesy ： Geometric geodesy 、 Physical geodesy 、 Space geodesy （ Fill in the blanks ）
2、 Precession and nutation （ Give a short answer , So the concept should be clear ）
3、P26 The map of geodetic coordinate system should be able to draw （ Short answer exam ）
4、 And did you copy me P49 That picture , He said he would have a big problem , If you don't, I'll send it to you （ This is very important , He said many times that he would work out a big problem , So remember ）
5、P81 The concept of geoid （ I think the explanation of nouns must test this , According to my own understanding ）
6、 The fourth chapter is mainly drawing , Except for the geodetic coordinate system , also P99 chart 4-1
7、P104 Relationship between space rectangular coordinate system and geodetic coordinate system （4-25）（4-26） Two sets of formulas , All remember
8、P124 4.6 The following passage （ I think it's possible to fill in the blanks , Of course, you'd better memorize it ）
9、P159-160 The Gauss projection zone calculates those sections , Because I don't know if he can calculate , You'd better have a look
10、P210 Four basic principles and methods of establishing national plane geodetic control network P227 Four layout principles of elevation network （ The fifth chapter is about these two points , I feel sure I will pass the exam ）
Well, these are the contents of his HKCEE, which I think should be close to ten , I didn't say otherwise , But these must be remembered .