About "3S"

3S technology is a general term for Remote Sensing, Geographical Information System and Global Position System. They are named after the fact that each of the three concepts contains an S in the corresponding English.

remote sensing

remote sensing, as its name implies, is remote perception. The legendary "clairvoyance" and "clairvoyance" have such ability. Through a lot of practice, human beings find that every object on the earth is constantly absorbing, emitting and reflecting information and energy, among which there is a form that human beings have recognized-electromagnetic wave, and find that the electromagnetic wave characteristics of different objects are different. Remote sensing is based on this principle to detect the reflection of electromagnetic waves and the electromagnetic waves emitted by surface objects, so as to extract the information of these objects and complete the long-distance identification of objects. For example, when a forest fire breaks out in Daxing 'anling, because the temperature of the burning trees is higher than that of the trees that are not on fire, they will radiate more energy in the thermal infrared band of electromagnetic waves than the trees that are not on fire. In this way, when the fire commander is worried about the raging fire, if a satellite carrying a thermal infrared band sensor passes over Daxing 'anling at this time, the sensor will photograph tens of thousands of square kilometers of Fiona Fang around Daxing 'anling. Because the forest on fire radiates more electromagnetic energy in the thermal infrared band than the forest without fire, the forest on fire in the image will show brighter light tones than the forest without fire. When the image was processed and handed over to the fire commander, the commander saw that the range of light on the image was so large, and the firefighters were only concentrated in a small place, indicating that the fire was pressing and more firefighters must be dispatched to different places to participate in the fire fighting immediately. The above example simply illustrates the basic principle and process of remote sensing, and involves many aspects of remote sensing. In addition to the basic feature that different objects have different electromagnetic wave characteristics mentioned above, there is also a remote sensing platform, which is a satellite in the above example, and its function is to stably carry sensors. In addition to satellites, commonly used remote sensing platforms include airplanes and balloons. When testing on the ground, a simple remote sensing platform like a tripod on the ground will be used. A sensor is an instrument installed on a remote sensing platform to detect electromagnetic waves of objects. According to different applications and band ranges, people have developed many kinds of sensors to detect and receive electromagnetic radiation of objects in the visible, infrared and microwave ranges. The sensor will convert these electromagnetic radiation into the original image according to certain rules. After the original images are received by the ground station, they have to go through a series of complicated processing before they can be provided to different users, and they can use these processed images to carry out their own work. According to incomplete statistics, so far, the total number of artificial satellites in the United States, Russia, France, China, India, Canada, Japan, Germany and Italy has exceeded 2,, including more than 5 remote sensing satellites and more than 1 large-scale ground remote sensing satellite receiving stations around the world. More than 3 Earth observation satellites will be launched in the first decade of the next century. The spectral resolution is as high as nanometer level, the ground resolution of commercial remote sensing image is as high as meter level, the radar image is multi-band and multi-polarization, and the data collected by remote sensing is extremely rich, and the data volume of the Earth Planet Project alone reaches 115 bytes a day. China has launched 68 satellites, including 1 scientific and technical satellites, 5 meteorological satellites, 1 resource satellite and 17 recoverable remote sensing satellites, which have obtained high-resolution panoramic photographic images and established a number of remote sensing satellite ground receiving stations, which can receive and process satellite image data such as Landsat TM, SPOT and RADARSAT. Many meteorological satellite receiving stations have been established to receive and process data from NOAA and geostationary meteorological satellites. A high-efficiency airborne combined platform for earth observation at middle and low altitude and a large number of ground observation stations have been established.

because of its obvious advantages in surface resources and environment monitoring, crop yield estimation, disaster monitoring, global change and many other aspects, remote sensing is developing rapidly. More ideal platforms, more advanced sensors and image processing technologies are constantly developing to promote remote sensing to play a greater role in a wider range of fields. When you travel or go on a field trip, in order not to get lost, you may bring a compass or compass to help you locate, determine the walking route, and mark it on the map to achieve the goal of locating. However, when positioning in this way, you are required to have certain skills, especially the ability to judge the relative position of surrounding targets. So, can you find a simple instrument that can directly tell us where we are? Yes, that's the global positioning system.

geographic information system

GIS (geographic information system) is a geographic information system that uses modern computer graphics technology and database technology to input, store, edit, analyze and display spatial information and its attribute information. The data stored and processed in geographic information system can be divided into two categories: the first category is the information reflecting the geographical and spatial position of things, called spatial information or spatial data (also called map data and graphic data); The second category is information related to geographical location that reflects other characteristics of things, called attribute information or attribute data (also called text data, non-graphic data). Through the unique management mode of the system for these two types of information, a two-way correspondence relationship is established between them. At present, the popular GIS platform softwares in China are ArcInfo, MapInfo, MGE and so on.

global positioning system

global positioning system (GPS) is a new generation of space satellite navigation and positioning system approved by the U.S. Department of Defense and jointly developed by the armed forces. Its main purpose is to provide real-time, all-weather and global navigation services for land, sea and air, and to be used for some military purposes such as intelligence gathering, nuclear explosion monitoring and emergency communication. It is an important part of the US global dominance strategy. After more than 2 years of research and experiment, it cost 3 billion dollars. By March 1994, 24 GPS satellite constellations with global coverage of 98% had been laid out.

Global Positioning System * * * consists of three parts:

Ground control part, which consists of main control station (responsible for managing and coordinating the work of the whole ground control system), ground antenna (injecting navigation messages into satellites under the control of main control station), monitoring station (data automatic collection center) and communication auxiliary system (data transmission);

Space part, which consists of 24 satellites and distributed on 6 orbital planes;

the user equipment part is mainly composed of a GPS receiver and a satellite antenna.

The main features of p>GPS global positioning system are:

All-weather, not affected by the weather; Global coverage; Three-dimensional fixed-point and fixed-speed timing with high precision; Fast, time-saving and efficient; Widely used and multifunctional.

The main uses of p>GPS global positioning system:

Land applications, mainly including vehicle navigation, scenic spot guide, emergency response, high-precision time-frequency comparison, atmospheric physical observation, geophysical resource exploration, engineering survey, deformation monitoring, crustal movement monitoring, municipal planning control, etc.

marine applications, including the determination of the best voyage route of ocean-going vessels, real-time dispatching and navigation of vessels, marine rescue, marine treasure exploration, hydrogeological survey, offshore oil well platform positioning, sea level fluctuation monitoring, etc.

aerospace applications, such as aircraft navigation, attitude control of aerial remote sensing, orbit determination of LEO satellites, missile guidance, aviation rescue and manned spacecraft protection detection.

there are many kinds of p>GPS satellite receivers, which are divided into geodetic type, all-station type, timing type, handheld type and integrated type according to their models. According to the purpose, it is divided into vehicle-mounted, ship-borne, airborne, satellite-borne and missile-borne. After more than 2 years of practice, it has been proved that GPS system is a high-precision, all-weather and global multifunctional system for radio navigation, positioning and timing. GPS technology has developed into a multi-field, multi-mode, multi-purpose and multi-machine high-tech international industry. Now, in addition to the global positioning system (GPS) of the United States, satellite systems with similar functions of GPS include the global satellite navigation system of Russia, the developing European navigation and positioning satellite system, and the multifunctional satellite augmentation system of Japan. Global positioning system or GPS is just a synonym for this kind of system. It is an inevitable historical development that mankind has turned from aerial photogrammetry to aerospace digital photogrammetry based on remote sensing, from single map drawing to the construction of electronic map database and geographic information system, and the technical structure has also developed from single technology to "3S" integrated technology and "3S" operating system based on network environment.