Surveying and mapping is ancient and modern, and painting is now developing into a new discipline-geospatial science. Surveying and mapping is an ancient discipline with a long history. The development of surveying and mapping in ancient times, there is a legend that after the Nile flooded, surveying and mapping reorganized the farmland boundary. In the 7th century BC, Guan Zhong had collected 27 early maps in his book Guanzi. From the 5th century BC to the 3rd century BC, China recorded the earliest guide tool "Sina" made of magnets. In BC 130, topographic maps and garrison maps appeared in the early Western Han Dynasty, which were the earliest maps found in China. With the progress of human society and the continuous development of science and technology, great changes have taken place in the theory, technology, methods and subject connotation of surveying and mapping. Especially in the contemporary era, due to the development of space technology, computer technology, communication technology and geographic information technology, the theoretical basis, engineering technology system, research fields and scientific objectives of surveying and mapping are very different from those of traditional surveying and mapping. Surveying and mapping is increasingly becoming a new discipline at home and abroad-Geospatial Information Science (Geomatics for short).
The main research object of surveying and mapping is the earth (of course, it will develop into outer space and study other planets in the future). The gradual deepening of human understanding of the shape of the earth requires accurate determination of the shape and size of the earth, thus promoting the development of surveying and mapping. Therefore, surveying and mapping can be said to be a branch of earth science. Surveying and mapping research results are information products represented by maps, and the evolution of maps and their production processes and methods is a major symbol of surveying and mapping progress. Measuring instruments are tools for measuring and obtaining observation data, and the development of measurement depends largely on the creation and reform of measuring methods and measuring instruments. The development of surveying and mapping instruments has gone through the early vernier theodolite to small flat plate, large flat plate, level, aerial camera, pendulum, gravimeter, total station, measuring robot and digital plotter. The results have also changed from hand-drawn maps to digital maps, from the original two-dimensional maps to the current three-dimensional maps and four-dimensional maps. The "Sky Map" recently developed by the State Key Laboratory of Surveying, Mapping, Remote Sensing and Information Engineering of Wuhan University is a good representative.
The scientific position and function of surveying and mapping are of great significance. Function in scientific research: Measurement plays an important role in exploring the mysteries and laws of the earth and deeply understanding and studying various problems of the earth. At present, the measurement technology can provide almost arbitrary time-domain resolution series, and can detect instantaneous geographical events such as crustal movement, temporal and spatial changes of gravity field, tides and earth rotation. These observations can be used to study the materials in the earth, especially to solve geophysical problems. Surveying and mapping plays an extensive role in the national economy. Abundant geographic information is an important foundation of national economy and social informatization, which provides important resources for building a "digital city" and a "digital China". In today's modern war, surveying and mapping plays an irreplaceable role in the positioning, launching and precise guidance of weapons. In addition, surveying and mapping has played an indelible role in disaster prevention and mitigation. In the 2008 Wenchuan earthquake, the station map played a guiding role in disaster relief and reduced the heavy losses caused by the disaster. In the future, surveying and mapping will still play a role in disaster prevention and mitigation, and the Civil Affairs Bureau attaches great importance to the role of surveying and mapping.
Surveying and mapping classification. With the development of surveying and mapping technology and the passage of time, sub-disciplines such as geodesy, general surveying, photogrammetry, engineering surveying and marine surveying and mapping have been formed in the process of development. Geodesy is a theory and method to study and determine the shape, size and gravity field of the earth, as well as the geometric position of ground points. General surveying studies the theory and method of control survey and topographic mapping in local areas of the earth's surface. Local area means that when surveying and mapping in this area, the curvature of the earth can be ignored and treated as a plane without affecting the accuracy of surveying and mapping. Photogrammetry studies the theory and method of collecting the image information of the measured object by camera or other sensors, and then processing and analyzing it to determine the shape, size and position of the measured object and judge its properties. Surveying and mapping a large area of surface morphology mainly depends on aerial photography. Engineering surveying studies the surveying theories, techniques and methods at all stages of design, construction and management in engineering construction. Provide accurate survey data and large-scale maps for engineering construction, and ensure reasonable site selection, design construction and effective management. Marine surveying and mapping studies the theory and technology of surveying and mapping marine water bodies and seabed. It provides guarantee for ship navigation safety and marine engineering construction. Cartography studies the theory and method of maps and their compilation. I will briefly describe these branches according to my understanding.
geodesy
Geodesy is a branch of surveying and mapping. Study and determine the shape, size and gravity field of the earth, and determine the geometric position of ground points. Determining the size of the earth in geodesy refers to determining the size of the earth ellipsoid; Studying the shape of the earth is studying the shape of the geoid; Determining the geometric position of the ground point refers to determining the position of the ground point with reference to the ellipsoid of the earth. The ground point is projected onto the ellipsoid of the earth along the normal direction. The horizontal position of the point is expressed by the geodetic latitude and longitude of the projection point on the ellipsoid, and the geodetic elevation of the point is expressed by the normal distance from the ground point to the projection point. The geometric position of this point can also be expressed by three-dimensional coordinates in the spatial rectangular coordinate system with the center of mass of the earth as the origin. Geodetic survey provides horizontal position control network and elevation control network for large-scale topographic mapping, gravity control point for underground mineral exploration, and accurate coordinates of ground stations and data of earth gravity field for launching artificial earth satellites, missiles and various spacecraft.
The basic task of geodesy is 1, to study the whole world, to establish a time-varying earth reference frame, to study the theory and method of the earth's shape and its external gravity field, to study the geodynamic problems such as describing the polar shift solid tide and crustal movement, and to study the theory and method of high-precision positioning. 2. Determine the shape of the earth and its external gravity field and its changes with time, establish a unified geodetic coordinate system, study crustal deformation (including vertical fluctuation and horizontal displacement of the crust), and determine the polar shift, ocean surface topography and its changes. Study the shape and gravity field of the moon and planets of the solar system. 3. Establish and maintain national and global astronomical leveling networks, precision leveling networks and marine geodetic control networks with high technical level to meet the needs of national economy and national defense construction. 4. Research instruments and methods to obtain high-precision measurement results. 5. Study the mathematical transformation of the projection of the earth's surface onto ellipsoid or plane and the related geodetic calculation. 6. Study the theory and method of large-scale, high-precision, multi-category ground network, space network and their combined networks, as well as the establishment and application of survey database.
Geometric geodesy. Since19th century, many countries have carried out national astrogeodesy, the purpose of which is not only to determine the size of the ellipsoid of the earth, but also to provide accurate geometric positions of a large number of ground points for the mapping of national topographic maps. In order to achieve this goal, a series of theoretical and technical problems need to be solved, thus promoting the development of geometric geodesy. First of all, in order to check a large number of astronomical geodetic observation data, eliminate contradictions among them, get the most reliable results and evaluate the observation accuracy, French A.M.Legendre published the least squares theory for the first time in 1806. In fact, German mathematician and geodetic scientist C·F· Gauss had applied this theory to calculate the orbit of asteroids as early as 1794. After that, he used the least square method to process the astronomical geodetic results, which developed to a quite perfect degree, resulting in the survey adjustment method, which is still widely used in geodesy. Secondly, the calculation of triangle and geodetic coordinates should be carried out on ellipsoid. 1828, Gauss proposed the solution of ellipsoid triangle in his book "General Theory of Surfaces". Many scholars have put forward many formulas for calculating geodetic coordinates. 1822, Gauss also published a conformal projection method for projecting an ellipsoid onto a plane, which is the best method to convert geodetic coordinates into plane coordinates and is still widely used today. In addition, in order to calculate the major semi-axis and oblateness of the earth ellipsoid by using the results of astrogeodesy, Helmert proposed a method to calculate the ellipsoid parameters that are most suitable for the geoid and its position on the earth under the condition that the sum of the squares of the vertical deviations of all astronomical points in the astrogeodesy network is minimum. This method is called area method later.
Physical geodesy. France's A.M.Legendre first published the least squares theory in 1806. In fact, German mathematician and geodetic scientist C·F· Gauss had applied this theory to calculate the orbit of asteroids as early as 1794. After that, he used the least square method to process the astronomical geodetic results, which developed to a quite perfect degree, resulting in the survey adjustment method, which is still widely used in geodesy. Secondly, the calculation of triangle and geodetic coordinates should be carried out on ellipsoid. Many scholars have put forward many formulas for calculating geodetic coordinates. 1822, Gauss also published a conformal projection method for projecting an ellipsoid onto a plane, which is the best method to convert geodetic coordinates into plane coordinates and is still widely used today. In addition, in order to calculate the major semi-axis and oblateness of the earth ellipsoid by using the results of astrogeodesy, Helmert proposed a method to calculate the ellipsoid parameters that are most suitable for the geoid and its position on the earth under the condition that the sum of the squares of the vertical deviations of all astronomical points in the astrogeodesy network is minimum. This method is called area method later.
Satellite geodesy. By the middle of the 20th century, both geometric geodesy and physical geodesy had developed to a fairly perfect level. However, because astronomical geodesy can only be carried out on land, it cannot cross the ocean; Gravity survey has only a small amount of data in ocean, mountain and desert areas, so the determination of the earth's shape and gravity field has not been satisfactory. It was not until 1957 that the first artificial earth satellite was successfully launched that satellite geodesy came into being, which made geodesy develop to a brand-new stage.
Photogrammetry
Photogrammetry studies the theory and method of collecting the image information of the measured object by camera or other sensors, and then processing and analyzing it to determine the shape, size and position of the measured object and judge its properties. Surveying and mapping a large area of surface morphology, mainly using aerial photogrammetry. Photogrammetry can be divided into aerial photogrammetry, space photogrammetry and ground photogrammetry according to the different positions of cameras when obtaining ground images. Aerial photogrammetry: It is the most commonly used photography method to put a camera on a plane to photograph the ground. Aerial photogrammetry uses a special large format camera, also known as aerial camera. Space photogrammetry: Photogrammetry technology developed with the development of space, satellite and remote sensing technology, in which a camera is installed on the satellite. In recent years, the successful application of high-resolution satellite photography has become an important resource for national basic surveying and mapping, urban and territorial planning. Near-earth photogrammetry is a kind of photogrammetry with cameras installed on the ground.
Some basic principles of photogrammetry include the basic relationship between images and objects, the relationship between images and pictures, the internal and external orientation elements of the camera, the * * * line equation, the stereoscopic observation method and so on. The measurement and interpretation of images are mainly carried out indoors, without touching the object itself, so they are rarely limited by climate, geography and other conditions; The photographed image is a true reflection of the objective object or target, with rich information and intuitive image, from which people can obtain a lot of geometric and physical information of the studied object; It can take instantaneous images of dynamic objects and complete the measurement work that is difficult to achieve by conventional methods; Suitable for large-scale topographic mapping, with high speed and efficiency; The products have various forms, and can produce paper topographic maps, digital line drawings, digital elevation models, digital orthophoto maps, etc.
Research direction of photogrammetry. 1. digital photogrammetry: based on aerial images and satellite meters high-resolution images, expand the theory and algorithm of computer stereo correlation, develop new methods for determining and refining stereo geometric models, and study new technologies for digital stereo mapping in difficult areas; A new fast calibration algorithm of digital camera in close-range photogrammetry, the accurate matching of digital images, and the problems in automatic monitoring of industrial production process and deformation monitoring of civil engineering buildings (such as bridges and tunnels) are studied. 2. Remote sensing technology and application: a new remote sensing method based on multi-spectral, multi-resolution and multi-temporal satellite images to study land surface change and geological survey; To study effective methods to detect changes in earth resources (such as land use) and develop semi-automatic or full-automatic remote sensing monitoring means; Develop practical remote sensing systems to monitor urban environmental pollution and natural disasters (such as floods, forests, crop diseases and insect pests) and so on. Based on synthetic aperture radar images, three-dimensional surface reconstruction, large-scale precise surface deformation detection (including landslide, urban subsidence and crustal deformation) and interferometric radar (InSAR) meteorological change monitoring are carried out. 3.3S technology and application Study the method and algorithm of vehicle-mounted CCD sequence image mapping, and provide fast and effective ground remote sensing measurement means for linear engineering survey; This paper studies the mode and method of 3S technology integration, including remote sensing (RS), global positioning system (GPS) and geographic information system (GIS), and explores a brand-new survey and design method for western railway and highway construction.
graphics
Map cartography is a subject that studies maps, their compilation and application. It studies the spatial distribution, interrelation and dynamic changes of various phenomena in nature and human society with map graphics, and has the duality of regional discipline and technical discipline, also known as cartography.
Theory and technology of cartography. Map compilation studies the theory and technology of making maps. It mainly includes: the selection, analysis and evaluation of cartographic data, the geographical study of cartographic area, the determination of map scope and scale, the selection and calculation of map projection, the representation of various elements of map content, the principle and implementation method of map synthesis, the technology and procedure of map making, and the drafting of map editing outline. Map decoration studies the manifestation of maps. Including map symbols and color design, three-dimensional representation of landforms, drawing of published original maps and atlas binding design. Map printing studies the theory and technology of map reproduction. Including map copying, copying, painting, plate making, proofing, printing, binding and other technologies. In addition, map application has become an integral part of cartography. Mainly study map analysis, map evaluation, map reading, map measurement and map making.
The development trend of cartography With the development of modern science and technology, cartography has entered a new stage of development. Its main characteristics and trends are as follows: ① Cartography, as a regional discipline, has shifted its research focus from general cartography to thematic cartography, and has developed into comprehensive cartography, practical cartography and systematic cartography. Cartography, as a technical subject, is developing in the direction of computer-aided mapping, which may gradually replace the manual mapping method that has lasted for thousands of years. ③ With the mutual penetration of cartography and other disciplines, some new concepts and theories have emerged. Such as map information theory and map transmission theory, focus on the display, transmission, conversion, storage, processing and utilization of map graphic spatial information; The map mode theory of establishing map mathematical model and digital model through map graphic modeling is studied. Map perception theory is to study the process and effect of users' perception of map graphics and colors; Study and establish map semiotics of map language, and so on.
engineering survey
Engineering survey is a subject that studies the theory and technology of control, topographic mapping, construction lofting and deformation monitoring in various stages of engineering construction and natural resources development. Surveying and mapping science and technology (or surveying and mapping) is a first-class discipline with a long history and modern development. No matter how the discipline develops, how the service field is broadened, how the intersection with other disciplines is increased or strengthened, how the discipline is integrated and subdivided, and how the name of the discipline is changed, the nature and characteristics of the discipline will not change.
Theoretical adjustment theory of engineering survey. Least square method is widely used in survey adjustment. Least square configuration includes adjustment, filtering and estimation. Conditional adjustment model with constraints is called generalized adjustment model, which is a unified model of various classical and modern adjustment models. The theory of measurement error is mainly manifested in the study of model error, which mainly includes: identification or diagnosis of functional model error and random model error in adjustment; The influence of model error on parameter estimation and the statistical properties of parameters and residuals; Relationship between ill-conditioned equation and control network design and its observation scheme. Because of the need to check the stability of datum points of deformation monitoring network, free network adjustment and quasi-stable adjustment have appeared and developed. The study of gross error of observation value promotes the research and development of reliability theory of control network and the theory of distinguishing gross error between deformation and observation value of deformation monitoring network. In view of the objective fact that there are gross errors in the observed values, robust estimation (or robust estimation) appears; Aiming at the possibility of ill-conditioned coefficient matrix of normal equation, a biased estimation is proposed. Unlike least squares estimation, robust estimation and biased estimation are called non-least squares estimation.
Marine geodesy and mapping
Marine surveying and mapping is the surveying and mapping of marine water body and seabed. It mainly includes hydrographic survey, marine geodesy, submarine topographic survey and marine thematic survey, as well as the compilation of nautical charts, submarine topographic maps, various marine thematic maps and marine atlas.
Basic theories and methods of marine surveying and mapping. The survey methods mainly include marine seismic survey, marine gravity survey, marine magnetic survey, submarine heat flow survey, marine electrical survey and marine radioactivity survey. Because of the existence of marine water bodies, it is necessary to use marine survey vessels and special measuring instruments for rapid and continuous observation, with one vessel for multiple purposes and comprehensive investigation. Basic survey methods include: ① route survey. Which is the profile. Understand the basic characteristics of geological structure and geophysical field in this sea area. ② Area measurement. According to the mapping scale set by the task, a measuring network with a certain distance is arranged. The larger the scale, the denser the network density. Radio positioning system and satellite navigation positioning system are widely used in marine survey. Compared with land survey, the basic theory, technical methods and measuring instruments and equipment of marine survey have many characteristics of their own. The main reason is that the measurement content is comprehensive, which requires a variety of instruments to cooperate with the measurement and complete a variety of observation items at the same time; The conditions in the survey area are complex, and the sea surface fluctuates due to the influence of tides and meteorology. Most of them are dynamic operations, and the surveyors can't see the bottom of the water area with naked eyes, so it is difficult to measure accurately. Generally, radio navigation system, electromagnetic wave range finder, underwater acoustic positioning system, satellite integrated navigation system, inertial navigation integrated system and astronomical method are used to determine control points and positioning measuring points. Using underwater acoustic instruments, laser instruments and underwater photogrammetry methods to measure water depth and seabed topography; Marine geophysical survey adopts satellite technology, aerial survey, marine gravity survey and magnetic survey.
Modern surveying and mapping new technology
With the rapid development of electronic information technology, communication technology and network technology, surveying and mapping is also facing opportunities and challenges. The improvement of surveying theory, methods and instruments has promoted the development of surveying and mapping. Nowadays, surveying and mapping not only greatly improves the measurement accuracy, shortens the measurement time and reduces the labor intensity, but also makes surveying and mapping workers no longer "migrant workers" in people's eyes. These new technologies include: 1, satellite navigation and positioning technology. The positioning systems represented by American GPS, Russian GLONASS, China Beidou and Galileo, which are under construction in the European Union, have brought great convenience to surveying and mapping and improved the accuracy. 2. Remote Sensing is a modern science and technology. Without touching the object itself, the electromagnetic wave information of the target is collected by sensors, and the target is identified after processing and analysis. Our remote sensing in Wuhan University is very strong, ranking first in Asia. 3. Digital map drawing technology. 4.GIS (Geographic Information System) GIS geographic information system is a technical system based on geospatial database, supported by computer software and hardware, and applying the theory of system engineering and information science to scientifically manage and comprehensively analyze geographic data with spatial connotation, thus providing information needed for management and decision-making. Simply put, geographic information system is a technical system that comprehensively processes and analyzes geospatial data. 5, 3S integration technology. That is, the integration of GPS, GIS and RS technology is the current development trend at home and abroad. In the integration of 3S technology, GPS is mainly used to provide the spatial position of objects in real time and quickly. RS is used to provide large-scale geometric and physical information of surface materials and their environment in real time and quickly, as well as their various changes; GIS is a platform for comprehensive processing, analysis and application of spatio-temporal data from multiple sources. 6. Virtual reality modeling technology is an advanced man-machine communication system composed of computers.
Surveying and mapping is extensive and profound, and our understanding of it is still superficial, but I believe that in the future study, we will have a deeper understanding of it. In the near future, we will devote ourselves to surveying and mapping and the construction of the motherland, and become qualified surveying and mapping workers and successors of the construction of the motherland in the 2/kloc-0 century!