I'd like some detailed information about GIS.

Digital globe

First of all, the proposal of "digital earth"

As a complete term, digital earth first appeared in the scientific and technological circles in the second half of 1997. 1998 65438+1October 3 1 day, US Vice President Al Gore delivered a speech entitled "Digital Earth-Understanding our Earth in the 2 1 century" at the California Science Center, and took the lead in shouting the word "Digital Earth" in public. He said, "I believe we need a' digital earth', a kind of earth that can embed massive data." Since then, Gore has mentioned the digital earth in many public occasions. In fact, NASA started a project called DIGITA EARTH in the second half of last year. After Gore's speech was made public on June 5438+1October 365438+1October 0, NASA started another Digital Earth project.

Generally speaking, the digital earth is to input the earth, its activities and the temporal and spatial changes of the whole earth environment into the computer by digital means, realize online circulation, and make it serve human survival, sustainable development and daily work, study, life and entertainment to the maximum extent.

Strictly speaking, digital earth is a multi-resolution, multi-scale, multi-temporal and multi-variety description of the earth based on computer technology, multimedia technology and mass storage technology, with broadband network as the link, and using mass earth information, and it is used as a tool to support and improve human activities and quality of life.

The core idea of digital earth is to deal with the natural and social activities of the whole earth by digital means, make maximum use of resources, and enable ordinary people to conveniently obtain the information about the earth they want to know in a certain way; It is characterized by embedding massive geographic data to realize multi-resolution and three-dimensional description of the earth, that is, virtual earth.

Second, the meaning of "digital earth"

In Gore's own words, his definition of "digital earth" is "a multi-resolution three-dimensional description of our planet that can embed massive geospatial information". This expresses the main characteristics of the "digital earth": First, it takes massive geospatial information as the main object. It includes not only space earth information, but also huge satellite image information. It includes both public space information and business information. These spatial information are multi-resolution and distributed all over the world. The second is the global information infrastructure that supports the integration of massive spatial image information and multi-source earth information and real-time network application, that is, the running environment. Network users can extract multi-source earth information and image information distributed in any different nodes in the world and integrate them in cyberspace. Thirdly, information processing technology based on object-oriented intelligent virtual reality computing, three-dimensional description and multimedia display of earth phenomena, helps human beings to better understand their own planet in a way that human beings can understand, and even opens up a "laboratory without walls" for all kinds of network users to understand "our planet", and also serves to solve a series of sustainable development problems and promote economic development. Therefore, "digital earth" is a social project involving a wide range, which needs the joint construction of various network users such as government, enterprises, scientific research and teaching units.

Gore put forward six key technologies, such as computing science, mass storage, satellite images, broadband network, interoperability and metadata, which are needed to build a "digital earth", and put forward the indicators for the beginning of the next century around the above characteristics. Judging from the key technologies put forward at present and their goals to be achieved at the beginning of the next century, there are specific technical aspects. For example, a series of new technologies, such as establishing a standardized spatial data framework, realizing real-time transmission, sharing and processing technology of spatial information network based on spatial data warehouse and high-resolution satellite data, and developing online intelligent virtual reality computing based on object-oriented network, all belong to the frontier fields facing 2 1 century, and are also the focus of the "Digital Earth" plan of the United States. The technical research focuses on the network application integration of Shanghai spatial image information and multi-source earth information on the "information superhighway", that is, with the support of multi-resolution remote sensing (mainly satellite) images and NSDI, the application environment is built on NII and GII to provide intelligent virtual reality calculation, multi-resolution three-dimensional description and decision-making support for various applications. The first step is to realize the network integration and * * * sharing of massive space image information and earth information.

Third, the role of "digital earth"

Digital Earth is one of the most important signs of the world entering the information age, and it plays a very important role in developing the global information industry.

Using digital earth on computer can describe the process, law, influence and countermeasures of global change in multi-resolution, multi-scale, multi-time and various three-dimensional descriptions and various simulations, thus improving human's ability to cope with global change.

Through the digital earth, people can know the latest and most comprehensive implementation situation anywhere in the world, and it has a wide application prospect in ecological environment protection, climate change prediction, earthquake prediction, land use planning, precision agriculture, disaster reduction, combating criminal activities, diplomacy, national defense and government macro-decision.

Relying on the digital earth, farmers can obtain the growth signs of their farmland, make action plans through GIS analysis, and then carry out farmland operations under the guidance of on-board GPS and electronic maps to prevent pests and diseases in time, and use pesticides, fertilizers and water where they must be used.

In terms of water conservancy construction, digital earth can simulate the environmental changes around the reservoir area and upstream and downstream after the completion of large reservoirs. On the one hand, it can provide decision-making basis for reservoir construction, and at the same time, it can clearly understand the possible problems after the completion of reservoirs, so as to formulate corresponding countermeasures.

In modern war and national defense construction, digital earth is of great significance. Establish various military geographic information systems serving strategy, tactics and campaigns, and use virtual technology to establish a digital battlefield, so as to grasp the initiative of the battlefield.

Ordinary people can study, shop, visit and travel on the digital earth, and they can also appreciate the local customs, literature and art, natural landscape, plants and animals and weather through the changes of time and space, as if they were there. Relying on the digital earth, users can see the earth emerging from space as long as they wear the display helmet, and open the window of the user interface to enlarge the digital image; With the continuous improvement of resolution, he saw the mainland, then the countryside, cities, and finally private houses, shops, trees and other natural and man-made landscapes; When he is interested in goods, he can enter the store, admire the clothes in the mall, and construct a virtual fit dress according to his body shape.

The arrival of the information age will change the way of human existence and development. The future distribution of benefits will be closely related to the digital earth. In the future conflicts of interest (including military conflicts), we will rely on the control of the digital earth to a great extent, and the leading party on the digital earth will launch diplomatic offensive, news dissemination, psychological warfare, political subversion, cultural aggression, data destruction and so on.

Fourthly, the background of the development of "Digital Earth"

From the development history of American information infrastructure, "Digital Earth" is a natural extension of the development of American national and global information infrastructure (NII and GII). As early as 198 1, American scholars proposed the concept of NII. 1992 during Clinton's presidential campaign, NII construction in the United States was put on the agenda as a national development strategy. It is planned to build a high-speed communication network connecting the United States in about 20 years (to 20 10), with a total investment of 400 billion US dollars, including 20 billion US dollars invested by the government. From 65438 to 0993, the US government further clarified five basic principles for developing NII: encouraging private investment, promoting competition protection, low price for the public, flexible and orderly environment, and high quality service to the world. From 65438 to 0994, the United States applied these principles to the construction of global information infrastructure (GII). As early as the early 1990s, the concept of "digital earth" was put forward in the documents about national information infrastructure (NII) in the United States, but it was not put on the agenda under the conditions of network technology at that time as the application field of NII development prospect.

1994, by issuing a presidential decree, the United States began to incorporate all kinds of technologies, policies, standards and human resources development necessary for the acquisition, processing, storage and distribution of geospatial data as part of the National Spatial Data Infrastructure (NSDI), and established the National Geospatial Data Exchange Network (NGDC), which is a network system supporting the operation of NSDI. The spatial data exchange center is located in USGS, and the Federal Geographic Data Committee (FGDC) relies on NGDC to coordinate the standardization and network sharing of geospatial information. This network system connects the producers, managers and users of global spatial data through spatial metadata technology, initially forms a distributed network system, and accelerates the standardization of global data and the integration and sharing of network applications through national coordination. NGDC has played an important role in strengthening the exchange of geographic information data in the United States and even the world. In fact, it has become a retrieval network linking the whole geospatial data (mainly in the United States at present) on the Internet, and any organization that can provide geospatial retrieval data (not metadata) through the Internet can become a member. However, in view of the network technical conditions in the early 1990s in the United States, the data involved in NSDI are mainly geospatial data, and a large number of spatial data from aerospace, aerial remote sensing (RS) and global positioning (GPS) and their network applications and integration have not been put on the agenda.

In the late 1990s, NII made remarkable progress and became an important factor for the sustained economic growth in the United States. Through the democratization of the Internet, the United States gradually unified the network address and transmission protocol standards, and formulated policies (data policy, technical policy and economic policy) to promote data sharing and network application, which accelerated the development of NII technology and application, and also provided conditions for the network application integration of massive spatial data. Its important symbol is the successful implementation of the second generation Internet, which is rapidly popularized all over the world, and its bandwidth reaches 10G per second. On the other hand, the application of global geographic information system and spatial information technology developed rapidly during this period, and developed countries such as the United States made remarkable progress in the digitization of earth data and the accumulation and application of spatial data. A considerable number of countries (especially developed countries) have established a large number of basic geographic databases and formed a system of regular updating and publishing. For example, the National Surveying and Mapping Department under the U.S. Geological Survey has completed the nationwide1:200,000 terrain database,1:0,000 terrain database and1:250,000 land use database, and is establishing the national 1:24000 terrain database and/kloc-0. Developed countries, especially the United States, still maintain a leading and monopoly position in the space technology and data market. "Digital Earth" was put forward under the above background.

To sum up, it is not difficult to see that the expansion from NII or GII to NSDI and then to Germany represents different technological development stages of NII or GII development in the United States. The types and scope of information supported by NII (GII) are constantly expanding, and the information processing function and technical level are constantly improving. That is, the "goods" on the "information superhighway" extend to geospatial data and the massive information of high-resolution satellite remote sensing; Processing technology extends to the high-speed transmission of geospatial information and multimedia information, and then develops in the direction of network integration and real-time (online interoperability) transmission, intelligent processing (virtual reality) and three-dimensional display of multi-source geospatial information and massive spatial information. At present, the production and management of conventional basic geographic data often mentioned in the discussion of "digital earth" belongs to the category of NSDI in the United States; For satellite images, the emphasis is on the application, especially the application of existing spatial information. Gore's speech on "Digital Earth" didn't even describe the key technologies of new spacecraft and sensors. The task of further improving the "construction of remote sensing earth observation satellite system" has always been done by the American space field. It can be seen that the proposal of "Digital Earth" in the United States has its specific economic, social and technical background, and is the product of the development of American space technology, information technology, network communication technology and their applications. From the perspective of space technology, "digital earth" is based on the abundant global earth observation data obtained by American satellites, aviation and ground stations. From the perspective of information technology and the construction and application of "information superhighway", it can be considered that "digital earth" has basically solved the standardization and standardization of Internet network transmission and management. Major breakthroughs have been made in the development of key technologies such as network bandwidth, large-capacity data storage and management, multimedia information network transmission processing and integration, and online operation of virtual reality and artificial intelligence technology in wide-area network environment. Under the background of the second generation Internet, a new round of NII and GII development planning with higher technical level is put forward, with the focus on promoting the development and utilization of existing spatial information resources (especially satellite data resources). Therefore, in a sense, the implementation of "Digital Earth" marks the accelerated integration of global spatial information technology, computer network communication technology and earth science technology represented by the United States in the 1990s at a higher technical level, and pushes them to a new beginning of application.

V. Countermeasures for Developing "Digital Earth" in China

China is a large developing country with a large population, and the socio-economic conditions and technical basis of informatization are significantly different from those of developed countries. We should actively respond to the challenge of "digital earth" in light of our national conditions and development stages. The following are some suggestions on the development and innovation of key technologies, the construction of spatial information infrastructure and the development of geographic information industry.

1. Strengthen the development and innovation of key technologies of "Digital Earth" in China.

The development of six key technologies, such as computing science, mass storage, satellite images, broadband network, interoperability and metadata, is the focus of creating a "digital earth" in the United States. On the one hand, these key technologies are essential for any country to build and apply a "digital earth". As Gore said, "Most of the technologies and capabilities needed to build a" digital earth "are mature or developing". On the other hand, there is a big gap between China and developed countries in terms of technical indicators proposed by the United States at the beginning of the next century. Therefore, it is urgent to strengthen the research and innovation of key technologies related to "Digital Earth".

Among the key technologies of "Digital Earth", the commercialization of satellite images with resolution of 1 m is particularly noticeable, which means that high-resolution satellite data are widely used to support global spatial information analysis and processing, including real-time analysis and processing supported by powerful information systems and networks. This is not only of great significance to technological progress, but also means huge business opportunities and potential economic and social benefits, which are closely related to China's corresponding industries and national security. As a developing country, China needs to adopt a combination of import and independent innovation in key technology development and information infrastructure construction. Introduce mature technology to speed up the construction of spatial information infrastructure in China; At the same time, according to China's national conditions, application needs and national security needs, we will focus on developing and innovating key technologies of "digital earth" and narrow the gap with developed countries. At present, there is an urgent need to make breakthroughs in two areas related to national economy and national defense security, namely, speeding up the establishment of China's independent, stable and powerful satellite earth observation system and the backbone network for spatial information transmission, getting rid of the situation of over-reliance on foreign satellite data sources, network transmission and management technology, and creating necessary conditions for enhancing the international competitiveness of China's geospatial information industry. Facing the increasingly severe challenges, it is necessary to further emphasize the overall planning of the country and the cooperation between departments. The situation of information blockade and low-level redundant construction between departments should be ended as soon as possible. These include speeding up the development and launch of China remote sensing satellites, establishing its own series of remote sensing satellites and independent and stable space information sources for earth observation; Establish and improve the digital product technology system, infrastructure and market environment for the collection, processing, release and application of spatial geographic information to meet the needs of various applications for spatial information sources, especially for the dynamic observation and analysis of land resources and environment. As a vast country, China needs to establish its own series of Earth observation satellites to make due contributions to mankind. At the same time, the development of key technologies of "Digital Earth" should be combined with the construction, development and application of NSII, so as to innovate in development, cultivate talents and markets, and promote the transformation of technological achievements and the development of information industry.

2. Accelerate the construction of spatial information infrastructure in China.

In the current international economic and technological integration environment, "Digital Earth" also provides an opportunity for China to develop the National Spatial Information Infrastructure (NSII) with high efficiency and low cost. In view of the fact that "Digital Earth" is a plan dominated by the construction and application of global spatial information infrastructure, it is basically consistent with the construction and application (market) of China's national spatial information infrastructure. "Digital Earth" in China is actually equivalent to the development and application of national spatial information infrastructure in China.

The six key technologies of "Digital Earth" also belong to the key technologies that are indispensable for the development of NSII in China. At present, there is a big gap between China and developed countries in technology, but it has greater potential in application. In particular, the commercialization of 1 m resolution satellites and the sharp price reduction of commercial satellite data, including terrestrial satellites, have provided rare opportunities for satellite data users in China. On the one hand, we should solve the severe challenges faced by China's corresponding technology industry development and national security through technological innovation, on the other hand, we should seize the opportunity to use spatial data with higher resolution and lower price to improve the application efficiency, personnel training and market cultivation in various fields.

As a developing country, on the one hand, China needs to strengthen scientific and technological innovation in six key technical fields of "digital earth" and narrow the gap with developed countries; On the other hand, we must speed up the construction of the production and application system of basic geographic data in China, and promote the development and expansion of China's spatial information industry. This is conducive to guiding and promoting the development and application of spatial information technology at different technical levels (the application of mature technology and the transformation of cutting-edge technology innovation) in China, which is in line with the social and economic background of industries, regions and enterprises with large gap between the development and application level of information technology and economic strength in China. The main ways to develop China's "Digital Earth" can be summarized as the following three aspects:

The first is to revitalize information resources and promote the development of applications. Give full play to the potential of China's existing information resources, take advantage of the opening of high-resolution satellite data in developed countries, accelerate the integration of multi-source information, promote the construction of "digital earth" application system, improve the development and utilization level of existing spatial data, and achieve better application benefits. China has more advantages and initiative in the development and utilization of information resources. On the one hand, as a developing country, China may use spatial geographic information with higher resolution, richer and cheaper. On the other hand, China has great potential in this respect. Since the founding of New China, China has carried out a large-scale geological survey and accumulated a large number of geo-spatial information resources with strong systematicness and high standardization, especially the geographical information of natural resources survey is not only very rich, but also relatively systematic and comprehensive. However, the level of development and utilization of these information resources is very low, and there is great potential for digitalization, networking, enjoyment and deep processing. In particular, it has obvious advantages and prospects in improving the technical level and efficiency in the fields of land survey, urban management and distance education in China.

The second is key technological innovation and infrastructure development. Accumulate necessary experience through the practice of NSII construction, carry out the innovation and application of key technologies of "Digital Earth" according to the actual situation in China, promote the technical update and sustainable development of NSII, gradually establish the operation and management system of spatial information infrastructure with China characteristics, form China's independent space Earth observation system, enhance the international competitiveness of China's spatial information technology and related industries, and safeguard national security.

The third is to promote the formation and development of high-tech industries. Through the development of spatial information infrastructure, we will promote the formation and development of China's spatial information system software industry, spatial information service industry and other related industries, open the market for their applications, and create the necessary technical and economic support environment.

In a sense, the commonweal and basic part of "Digital Earth" in the United States can correspond to the National Spatial Information Infrastructure (NSII) being developed in China, and its market-oriented application part is closely related to the application of geographic information resources in China and the informationization, networking, industrialization and marketization of related industries. China also has the requirements and conditions to create a "digital earth".

3. Vigorously cultivate and develop the spatial information industry in China.

China is rich in geographic information resources and has a wide range of spatial information applications. Since the 1980s, China has accumulated a large amount of spatial data and developed a large number of application systems based on spatial information, some of which have reached the international advanced level at that time, but there are still a large number of spatial data (including aerospace and aerial remote sensing data) and their research results have not been transformed into applications in time and have not played their due role in the informationization of national economy and social services. More than 70% of the domestic GIS software market is occupied by foreign software, and the spatial information industry is very weak. In view of the above problems, since the Ninth Five-Year Plan, China has taken the industrialization, integration and practicality of GIS, RS and GPS as the "most important" research topic, and organized the key technology development of the National Spatial Information Infrastructure (NSII) and its prototype, the National Resource Environment and Regional Economic Information System (NREDIS). These projects have promoted the enjoyment of spatial information and the formation and development of the corresponding geospatial information industry.

To sum up, in the face of the challenge of "Digital Earth", it is necessary to further strengthen the macro-organization and coordination of the country on the basis of the existing work, set up the key development projects of the National Spatial Information Infrastructure (NSII), integrate the R&D organizations of all parties concerned into the NSII development and application framework, promote the efficient development and utilization of China's spatial information resources and standardize network sharing, and make their own contributions to the construction of the global spatial information infrastructure.

Six, "digital earth" and its relationship with modern surveying and mapping

"Digital Earth" is a concept put forward by American Vice President Al Gore in a speech in June 1998+0. It is a dynamic description system, which can input a large amount of geographic information and perform multi-resolution processing. It is formed with the development of national information infrastructure (so-called national information superhighway). "Digital Earth" is a broad concept based on information infrastructure and spatial data infrastructure. Its technical basis includes computer technology, image processing technology, large-scale data storage technology, space earth observation technology and digital communication technology.

The formation and development of "Digital Earth" must first develop national information infrastructure and national spatial database. The latter mainly includes four parts: geospatial data framework, spatial data coordination, management and distribution, spatial data exchange standards and spatial data exchange websites. These projects and facilities are directly related to modern surveying and mapping work. In particular, the national spatial data framework, including geodetic control, digital orthophoto, digital elevation model, traffic, water system, administrative boundaries, public cadastre and other spatial basic data, their acquisition, processing and management are the business scope of surveying and mapping, and also the development direction of contemporary surveying and mapping.

The national L: 1, 000,000 and 1, 250,000 digital map databases built in China are the national legal spatial data framework. However, the scale of these two data frames is not large enough, so it is urgent to establish a national digital spatial database of 1: 50000 and a provincial digital spatial database of 1: 10000 based on national, provincial and municipal aerospace remote sensing images, so as to obtain the ground image of China with the resolution of 1 m. These are the national spatial data infrastructure and pioneers, and they are indispensable and important components, which will lay a solid foundation for China's "Digital Earth". On the basis of this framework, loading all the spatial information related to geographical location in China's economy, society, humanities and other industries, and constructing the national spatial data infrastructure from this will make extremely important contributions to solving the major problems such as population, resources, environment and disasters in China's social sustainable development, as well as the planning, protection and utilization of land resources, industrial and agricultural development and other related practical problems. Promote national economic development, ecological balance and improve people's quality of life. Therefore, the "digital earth" developed and formed in the world will make positive contributions to the sustainable development and social progress of human society around the world.