They allow obtaining spatial information about the earth's surface in the visible and infrared ranges of electromagnetic wavelengths. They are capable of detecting passive reflected radiation from the earth's surface in the visible and near infrared ranges. In such systems, the radiation hits the appropriate sensors that generate electrical signals depending on the intensity of the radiation.
In optoelectronic remote sensing systems, as a rule, sensors with continuous line-by-line scanning are used. Can be distinguished linear, transverse and longitudinal scanning.
The total scan angle across the route is called the angle of view, and the corresponding value on the surface of the Earth is bandwidth.
Part of the data stream received from the satellite is called a scene. The schemes for cutting the stream into scenes, as well as their size for different satellites, differ.
Optical-electronic ERS systems carry out surveys in the optical range of electromagnetic waves.
Panchromatic the images occupy almost the entire visible range of the electromagnetic spectrum (0.45-0.90 microns), therefore they are black and white.
Multispectral(multispectral) imaging systems generate multiple separate images for broad spectral areas ranging from visible to infrared electromagnetic radiation. The greatest practical interest at the moment are multispectral data from new-generation spacecraft, including RapidEye (5 spectral zones) and WorldView-2 (8 zones).
New generation satellites of high and ultra-high resolution, as a rule, survey in panchromatic and multispectral modes.
Hyperspectral imaging systems form images simultaneously for narrow spectral zones in all parts of the spectral range. For hyperspectral imaging, it is not the number of spectral zones (channels) that is important, but the width of the zone (the smaller, the better) and the sequence of measurements. So, a survey system with 20 channels will be hyperspectral if it covers the range of 0.50-070 microns, while the width of each spectral zone is no more than 0.01 microns, and a survey system with 20 separate channels covering the visible region of the spectrum , near, shortwave, mid and far infrared regions, will be considered multispectral.
Spatial resolution- a value that characterizes the size of the smallest objects distinguishable in the image. The factors affecting the spatial resolution are the parameters of the optoelectronic or radar system, as well as the orbital altitude, that is, the distance from the satellite to the captured object. The best spatial resolution is achieved when shooting in nadir, while deviating from nadir the resolution deteriorates. Space images can be of low (over 10 m), medium (10 to 2.5 m), high (2.5 to 1 m), and ultra-high (less than 1 m) resolution.
Radiometric resolution is determined by the sensitivity of the sensor to changes in the intensity of electromagnetic radiation. It is determined by the number of gradations of color values corresponding to the transition from the brightness of absolutely "black" to absolutely "white", and is expressed in the number of bits per pixel in the image. This means that in the case of a radiometric resolution of 6 bits / pixel, we have only 64 color gradations, 8 bits / pixel - 256 gradations, 11 bits / pixel - 2048 gradations.
”, Created with the support of NASA, astronauts on the ISS are surveying the planet from low Earth orbit. To date, they have taken over 1.8 million images. On the Portal website you can see 12 collections: "Earth Observatory", "Glaciers", "Volcanoes", "Craters", "Pictures of Natural Disasters", "Time-Lapse Video", "Photos of World Capitals", "Life at the Station" , "Infrared images". In the historical collection you can see photographs of the entire Earth, the passage of Venus across the solar disk in 2012 and night images of the planet. The earliest materials from the archive were obtained during the Mercury space program in the early 1960s.
One of the archive's most interesting tools is the Earth observation system, which broadcasts HD images from multiple cameras installed on the ISS. On the site you can also pass the test for knowledge of geography "" and see demonstrating individual parts of the Earth or space phenomena.
A team of seven people is working on the project. In the FAQ section, you can ask the researchers questions: how detailed a picture from space can be; what kind of photography equipment the team uses; why astronauts do not see the North and South Poles and do not have time to photograph the stars.
One of the most common questions is "Can you see the Great Wall of China from space?" In fact, it cannot be seen with the naked eye, but it is visible in the photographs - the Chinese Wall looks like a thread two pixels thick.
("img": "/wp-content/uploads/2015/01/nasa_011.jpg", "alt": "Gateway to Astronaut Photography 01", "text": "Klyuchevskaya Sopka, Kamchatka.")
("img": "/wp-content/uploads/2015/01/nasa_021.jpg", "alt": "Gateway to Astronaut Photography 02", "text": "Siachen Glacier, Himalayas.")
("img": "/wp-content/uploads/2015/01/nasa_031.jpg", "alt": "Gateway to Astronaut Photography 03", "text": "Extinct Demavand volcano, Iran.")
("img": "/wp-content/uploads/2015/01/nasa_041.jpg", "alt": "Gateway to Astronaut Photography 04", "text": "View of the Earth from the station.")
("img": "/wp-content/uploads/2015/01/nasa_051.jpg", "alt": "Gateway to Astronaut Photography 05", "text": "Full view of the Earth.")
("img": "/wp-content/uploads/2015/01/nasa_061.jpg", "alt": "Gateway to Astronaut Photography 06", "text": "Measuring depth from the International Space Station.")
("img": "/wp-content/uploads/2015/01/nasa_071.jpg", "alt": "Gateway to Astronaut Photography 07", "text": "Both the Northern and Southern hemispheres during the late In the spring and early summer seasons, mesospheric clouds are at their peak of visibility. Due to their specific brilliance, they are called silvery or luminous at night. ")
("img": "/wp-content/uploads/2015/01/nasa_081.jpg", "alt": "Gateway to Astronaut Photography 08", "text": "Time for nostalgia. The last flight of the Space Shuttle in the summer 2011. ")
("img": "/wp-content/uploads/2015/01/nasa_091.jpg", "alt": "Gateway to Astronaut Photography 09", "text": "The passage of Venus across the solar disk.")
("img": "/wp-content/uploads/2015/01/nasa_101.jpg", "alt": "Gateway to Astronaut Photography 10", "text": "Hurricane Ivan, September 2004.")
("img": "/wp-content/uploads/2015/01/nasa_11.jpg", "alt": "Gateway to Astronaut Photography 11", "text": "Historical shot of a stratovolcano.")
("img": "/wp-content/uploads/2015/01/nasa_12.jpg", "alt": "Gateway to Astronaut Photography 12", "text": "Gloriosus Islands, Indian Ocean.")
("img": "/wp-content/uploads/2015/01/nasa_13.jpg", "alt": "Gateway to Astronaut Photography 13", "text": "Bouvet Island is an uninhabited volcanic island in the South Atlantic Ocean . ")
("img": "/wp-content/uploads/2015/01/nasa_14.jpg", "alt": "Gateway to Astronaut Photography 14", "text": "Italy at night.")
("img": "/wp-content/uploads/2015/01/nasa_15.jpg", "alt": "Gateway to Astronaut Photography 15", "text": "Cities at night.")
("img": "/wp-content/uploads/2015/01/nasa_16.jpg", "alt": "Gateway to Astronaut Photography 16", "text": "Night lights over Russia.")
("img": "/wp-content/uploads/2015/01/nasa_17.jpg", "alt": "Gateway to Astronaut Photography 17", "text": "Two low pressure areas, Northeast Pacific Ocean. ")
("img": "/wp-content/uploads/2015/01/nasa_18.jpg", "alt": "Gateway to Astronaut Photography 18", "text": "Amazon River in sunlight.")
("img": "/wp-content/uploads/2015/01/nasa_19.jpg", "alt": "Gateway to Astronaut Photography 19", "text": "Sahara Desert after sunset.")
("img": "/wp-content/uploads/2015/01/nasa_20.jpg", "alt": "Gateway to Astronaut Photography 20", "text": "Tempano Glacier, South Patagonian Glacial Plateau.")
Images courtesy of Earth Science and Remote Sensing Unit, Johnson Space Center, NASA.
Space images, their types and differences from aerial photographs.
Non-photogrammetric survey systems.
Space images, their types and differences from aerial photographs.
Lecture number 3
Space photography is a development of aerial photography, but differs from the latter in the specificity of photography from high altitudes and from outer space. The survey is performed from a specific orbit along which the vehicle is moving. The parameters of the orbit, as well as the speed of the spacecraft, are always known, which makes it possible to determine the position at a given moment in time.
Compared to aerial photography (AFS), space images (CS) have a number of benefits.
Visibility CS provides an opportunity to study global phenomena of the earth's surface and its zonal patterns, and their small scale allows you to get rid of private details of the earth's surface and at the same time more clearly distinguish large features of the structure of the territory, which are difficult to notice in aerial photography.
All components of the landscape are depicted in one image, which provides an opportunity to study their interrelationships. Based on such images, the regularity of the distribution of snow is reliably established based on the relief of the earth's surface, the features of the structure of clouds over sea areas are revealed based on the direction and types of sea currents, etc.
An important advantage of the KS is the ability repeated images of the same areas of the earth's surface when performing surveys from satellites (artificial earth satellite) and orbital stations. This is of particular value when studying fast-paced phenomena - forest fires, melting snow cover, pest infestation on agricultural fields, etc.
KS also has a number disadvantages, complicating their practical use:
1.significant distortion photographic image due to even minor deviations optical axes photographic apparatus at an altitude of hundreds of kilometers, lead to large perspective distortions of images, especially in their edge zones;
2. distortion, due to sphericity the earth's surface. The smaller the scale of the pictures, the greater the distortion. The absolute values of these distortions increase towards the edges of the CS;
3. low linear resolution complicates the identification of terrain objects, the process of geographic referencing of the spacecraft.
Space photography of the earth's surface is carried out from spacecraft (SC). Along the flight paths, there is a rapid change in the illumination conditions of the earth's surface, which has a significant effect on the quality of the photographic image. This must be constantly taken into account when performing photographic work.
Spacecraft from which the Earth is surveyed in space move in different orbits and at different heights from the earth's surface. In lower orbits, the motion of these vehicles is substantially resisted by the atmosphere.
As the flight altitude increases, the satellite's lifetime increases and the area covered by the survey increases, but at the same time the spacecraft resolution decreases.
AES orbits are subdivided into circular and elliptical (Fig. 3.1).
Space images, their types and differences from aerial photographs. - concept and types. Classification and features of the category "Space images, their types and differences from aerial photographs." 2017, 2018.
Class: 6
Lesson topic: Image of the earth's surface on a plane. Aerial and satellite imagery. Geographic Maps
Target:
The student must know / understand: basic geographical concepts and terms, differences in plans and geographical maps in terms of content, scale, methods of cartographic representation
The student must be able to: conventional signs of the plan and map, read the plan and map, use the scale, apply the knowledge gained in practice.
Equipment: geographic atlases, wall geographic maps
DURING THE CLASSES
I ... Organizational moment. So, guys, you and I made imaginary travels with the help of the globe. But the globe is not always at hand, you cannot put it in your pocket, it takes up too much space in your backpack. What to do?
II. Learning new material
One of the most perfect images of the earth's surface is a geographic map.
How to show large areas of the earth's surface on a piece of paper?
A geographic map is a drawing of a large area of the earth's surface, made according to special rules. These rules are largely the same as the rules for building a plan. Like the plan, the map is drawn to scale using conventional symbols.
The map is much less detailed than the area plan. One centimeter of the map can correspond to tens and hundreds of kilometers, while one centimeter of the plan, as a rule, tens and hundreds of meters. The globe is convenient when we want to see the whole Earth, the plan is when we are working with a small area of the terrain. Territories of significant area are depicted on geographical maps. A geographic map is similar to a plan in that the surface of the Earth is also depicted on a plane, in scale and using conventional symbols. However, in comparison with the plan, the card has a number of very important distinctive properties.
First, the map is nowhere near as detailed as the plan. Due to the fact that large territories are depicted on the map, it is necessary to use a generalization, and a smaller scale. Not all are shown on the map, but only the main objects or phenomena. Real distances from tens to hundreds of kilometers can correspond to one centimeter on the map.
Secondly, many of the conventional signs that are used in drawing up maps differ from those that are adopted on the plans. For example, on the plan, forests are depicted in green, and on the physical map of the hemispheres and Russia - the lowest places of land - lowlands. Oceans, seas and their parts on the maps are shown in the form of clearly delineated outlines of blue (blue) color, mountains - in different shades of brown. To show the different depths of the seas and the heights of the mountains, a scale of heights and depths and the method of layer-by-layer coloring are used on the maps.
Symbols with their decoding form the legend of the map. The word "legend" means "what is read." The legend is the key with which the contents of the map are revealed. You should always start working with a map by studying its legend.
- So, what do we see in the legend of the map?(primarily a scale of depths and heights, which shows the height of the place)
- What does green mean?
- Why are there two shades of green?
- What other colors is the card represented? What do they mean?
The greatest difficulty in building a map is that it is necessary to depict a convex earth surface on a flat drawing. In this case, distortions inevitably arise. And the more territory is depicted on the map, the more distortion becomes. If you can neatly peel the skin off the orange by cutting it up and down, try spreading the skin flat on a piece of paper. Unfortunately, it will tear, first of all, at the edges. This is because a convex surface cannot be flattened without distortion. Notice, for example, how differently Australia and Greenland look on the globe and on the map of the oceans. The closer to the poles, the more noticeable the distortion on this map.
The first to solve this difficult task was the ancient Greek scientist Archimedes. It was he who developed the first projection - a method of transition from an image on a ball to an image on a plane. There are a great many projections. Maps, created in different projections, differ in the pattern of parallels and meridians.
How have maps changed over the course of human history?
The first drawings of the earth's surface appeared before writing was born. In primitive society, these blueprints were very simple. They were indicated by hunting places, main roads, rivers. The origins of modern cartography are to be found in Ancient Greece. After all, it was the ancient Greek scientists who pointed out the sphericity of the Earth, calculated its dimensions, suggested using the system of parallels and meridians, and, finally, created the first "real" map with a degree network.
The first collection of maps was placed in the work of the ancient Greek philosopher and astronomer Claudius Ptolemy "Geography". Since then, maps have been used not only for scientific, but also for practical purposes (for collecting taxes, calculating areas and distances).
In the Middle Ages, cartography, like science in general, was consigned to oblivion. The second birth of cartography is associated with the era of the great geographical discoveries. The discoverers sailed and walked along the maps, new lands were laid on them, the boundaries of new possessions were established. The invention of printing made it possible to quickly replicate cards. The map is no longer a single piece of art. It became widespread and accessible to all.
The Dutch cartographer Gerard Mercator made an invaluable contribution to the development of cartography in the Middle Ages. He created a projection in which all angles are shown without distortion. This projection made his name famous.
During the existence of cartography, the technology of making maps has changed. They were first drawn by hand based on direct measurements of the earth's surface. In the first half of the XX century. aerial photography came to the aid of cartographers. Currently, cartographic information is supplied mainly by artificial earth satellites, and is processed automatically using computers.
The computer memory stores the coordinates of millions of points on the earth's surface, the outlines of rivers and mountains, seas and lakes, borders of states and natural complexes. From these points and lines, according to the principle of the constructor, a new map is built. The cartographer just needs to choose what needs to be displayed on the map in accordance with its purpose and scale.
For example, on a political map, you need administrative boundaries and cities, but on a vegetation map it is better to show the boundaries of reserves and national parks.
Computer cards have a number of obvious advantages over traditional cards. They are distinguished by high precision. They are quickly created. Computer cards hardly have time to "age". Any change in geographical names, boundaries, outlines of objects in a matter of hours can be reflected on the map. A computer map allows you to quickly move from one scale to another and from one projection to another.
Since the computer card exists in electronic form, it is very affordable, compact and compatible with most computer programs. In the case when a computer map is supplemented with text material, tables, programs for constructing diagrams and graphs, the resulting computer product is called a geographic information system or GIS for short. With the help of GIS, you can quickly and efficiently draw up a plan for the construction of new roads, city blocks, determine the most profitable way to use land, and monitor areas of occurrence of hazardous natural phenomena.
Cartography today is not only a science about a map, but also a technology. It used to take years to create maps. As a result of the development of computer technology, electronic maps and atlases appeared, displayed on a computer screen. It is very convenient to use them. Maps can not only be viewed and flipped, but also combined with one another, reduced or enlarged. A huge amount of cartographic information is stored in computer databases. This allows you to create a wide variety of maps in a short time and use them together with text or other graphic information.
What's the best way to get an accurate, flat image of the earth's surface? For us, residents of the third millennium, the answer to this question is quite simple: we need to photograph it from above.
Surveying the earth's surface from aircraft allows you to get a detailed image of all the details of the terrain.
- Let's look at figure 27a on page 30 of your textbooks. What do you see in this picture?
Is it convenient to work with such a source of information?
Space images are taken from satellites orbiting the Earth.
On satellite images, cloud clusters and giant air vortices, flood zones and forest fires are clearly visible. Geologists use satellite images to identify fault zones on the Earth's surface, which are associated with mineral deposits, and probable earthquakes.
The coverage of the surveyed area and the scale of the images depend on the altitude at which the satellite flies. The higher the satellites fly from the Earth, the smaller the scale of the images and the detail of their images (Fig. 28 on page 31 of the textbook).
Geographic objects in space and aerial photographs are presented in an unusual form for us. Recognition of an image in pictures is called decryption. Computer technology plays an increasingly important role in decryption. Geographic plans and maps are made using satellite images.
So what is a geographic map?
A geographic map is a generalized reduced image of the Earth or a large area of its surface on a plane using conventional symbols.
The cards are very diverse. On many maps, in addition to depicting the surface of a certain territory, the location and connections of a variety of natural and social phenomena are shown. For example, on the maps of Russia, you can separately show the ethnic composition of the population, the composition of forests and their condition, and much more.
Geographic maps differ in the spatial coverage of the territory
The dimensions of the territory shown
World and hemispheres of the Continents, oceans and their parts of the States and their
parts
Figure 29, page 33 of the tutorial shows the maps different scales... You can see that:
The more space you need to depict, the smaller the scale should be;
The smaller the scale, the less detailed the content of the map.
Depending on the scale, maps are distinguished:
Large-scale - from 1: 10,000 to 1: 200,000;
Medium-scale - from 1: 200,000 to 1: 1,000,000;
Small-scale - smaller than 1: 1,000,000.
The smallest scale is used for the world map. In terms of spatial coverage, maps of the world, maps of continents and oceans, individual countries and their parts are distinguished.
By scale
Large scale Medium scale Small scale
The content of the cards is very diverse. They can be general geographic and thematic.
By content
General Geographic Thematic
General geographic maps show the general appearance of the space - mountains, plains, rivers, seas and other important natural objects. Thematic maps are dedicated to a separate topic. For example, a map of earthquakes and volcanoes, a map of natural areas, a political map showing the countries of the world. There are also different contour maps - only the outlines and outlines of geographic objects are plotted on them. You will also use these cards in the future, putting the necessary information on them.
Atlas is a collection of geographical maps of various subjects for a single territory: the world, a country, a region. Atlases are often supplemented with graphs, photographs, diagrams, and profiles. For the study of geography at school, the atlas is extremely important. The word "atlas" was introduced by Gerardus Mercator in the 16th century. In honor of the mythical king of Libya Atlas, who allegedly made the celestial globe.
So, MAPS ARE DIFFERENT IN SCALE, TERRITORY SIZE AND CONTENT.
The famous English writer RL Stevenson wrote: "They say that some people are not interested in maps - I can hardly believe that." Whether the maps are old or computer images - they are all tools of cognition and a means of allowing people to interact with each other. The map is an outstanding creation of human thought
An incorrectly created map can lead to dire consequences. The famous traveler Vitus Bering paid with his life, trusting an erroneous map, on which the "Land of Gama" was shown to the south of Kamchatka. Having searched for this land for three weeks in vain, he was caught in a storm and died during a forced wintering.
The map cannot be replaced with any description. It accurately conveys geographic information, is visual, allows you to study spatial relationships, plan and predict many phenomena and processes.
III. Practical work
1. Study your school atlas. Describe the types of maps by filling out the table in your notebook.
View of geographical maps of the atlas
What is depicted
1. Physical map of the hemispheres
2. Physical map of Russia
3. Political map of the world
2. When and why did geographic maps appear?
3. What is called a geographic map?
4. What properties does the card have?
5. How do maps differ in scale?
6. What does the legend of the map tell you about?
7. Select two features that distinguish the small-scale map: a) small areas of the territory are depicted; b) the curvature of the spherical surface of the Earth is taken into account; c) there is a degree grid; d) a large scale is used.
8. Map of scale 1: 500000 refers to: 1) large-scale; 2) medium-scale; 3) small-scale.
9. Analyze the physical map of your area, the edge and draw a conclusion to which maps in scale it belongs to.
10. On the physical map of Russia determine the scale - numerical, named and linear.
11. Distribute the maps as the detail and coverage of the depicted area decreases.
1) M - 1: 1,000,000 3) M - 1: 250,000
2) M - 1: 10000 4) M - 1: 100000
IV ... Home assignments:§ 9-10
Exercise
"1915, March 16 days, at latitude 79 ° and longitude from Greenwich 90 ° from the side of the drifting ship" Holy Mary "with good visibility and clear sky, an unknown vast land with high mountains and glaciers was seen to the east of the ship", - reports the report of the head of the expedition, Captain Tatarinov. Determine which land (islands) was discovered by this expedition.
Completing the assignment
1. Please note that the expedition took place in the Kara Sea. Determine which latitude and longitude the reported coordinates refer to.
2, Open the map of Russia in your atlas. Determine where longitudes and latitudes are labeled on this map.
3.Find the intersection point of the parallel 79 ° N on the map. sh. and meridian 90 ° E. etc.
4. Mark the found point with a pencil. Tell me what previously unknown land (islands) was discovered by the expedition of Captain Tatarinov.
How to describe the location of an object on the map?
It is important not only to be able to find an object on the map, but also to describe where it is. When describing the position of objects on the map, you can use the following rule: all objects lying on the meridians located to the left of this one are west of it, to the right of this one - to the east; all objects lying on parallels located above the given one are to the north of it, below - to the south.
5. In what direction is the nearest city indicated on the map from the islands discovered by the Tatarinov Islands? What is it called?
6. In what direction did the schooner Saint Mary follow to reach the nearest promontory on the coast? What is the name of this cape? Determine the distance to it (in kilometers).
7. What is the position of the open islands in relation to the Novaya Zemlya islands? New Siberian Islands?
8. In which part of the Kara Sea are the open islands located?
Additional material for the lesson
Using maps for scientific research
Examples of using maps
Geological and geomorphological
Study of the features of the spatial distribution of continents, oceans, mountain systems, mid-ocean ridges, analysis of their shape, position relative to the coordinate system and poles, hemispheric distribution, symmetry and asymmetry, zoning, etc. Obtaining information during measurements on maps about average, maximum and minimum dimensions planetary forms: heights, depths, areas, volumes, geophysical characteristics and connections between them. Identification of mineral deposits on maps using special techniques. Study of maps of the Earth, the Moon and the terrestrial planets of the Solar System to detect similarities in their structure, identify elements of similarity and differences in planetary structures to predict the structure and topography of planets. Use of relief maps for agricultural development of territories and land reclamation, for the design of structures and various types of construction.
Physico-geographical and landscape
Study of the structure and zoning of natural complexes, the establishment of relationships between the individual elements of these complexes. Comparison of landscape maps with other natural and socio-economic maps and in order to obtain an assessment of natural conditions for agricultural development, planning of anti-erosion and irrigation and drainage measures, the deployment of capital construction, the creation of recreational and tourist complexes. Study on maps of analogous territories to identify patterns in little-studied or hard-to-reach areas.
Oceanological and hydrological
Morphometric study of the ocean floor, analysis of the distribution of heights and slopes of shelves, slopes, hollows, the largest forms of underwater relief. Study of currents, interactions between the atmosphere and water masses, calculation of biomass, etc. Study of channel processes, structure and development of floodplains, river systems, basins. Study of the dynamics of processes occurring in river basins. Study of the hydrological characteristics of lakes and reservoirs.
Soil and geobotanical
Characteristics of soil and vegetation cover, the ratio of areas occupied by one or another soil or plant associations. Analysis of the relationship between contours on maps of soils, vegetation and other natural components. Study of the distribution of soils for agricultural development of the territory and land use.
Medical-geographical
Study of the spatial distribution of diseases, foci of epidemics. Establishing a link between the spread of diseases and the natural and social factors that contribute to their occurrence. Predicting the rate of spread of infections.
Socio-economic
Analysis of the characteristics of settlement, types of settlements, population density, etc. Territorial planning of long-term development of the economy, industrial and urban construction. Economic zoning.
Historical and geographical
A quantitative characteristic of the phenomena of the historical past. Getting an idea of the administrative-territorial structure, the development of cities, ports, industrial areas, trade relations, etc.
Environmental studies
Rational use and protection of the environment, integrated exploration of oceans and seas, forecasting natural disasters. Study of environmental pollution. Study of human influence on natural complexes. Monitoring and development of measures to prevent dangerous phenomena, preserve and reproduce natural resources.
A way of teaching map matching to terrain and a tutorial for doing it
They are taken with special aerial cameras installed on airplanes, and space images are taken from manned ships, orbital stations, automatic satellites using photographic and scanning equipment.
Aerial photographs are obtained using special cameras, which weigh tens of kilograms, are charged with photographic film, usually 18 cm wide, and installed above a special hole in the aircraft fuselage so that the lens "looks" directly at the Earth. Already during the First World War, military pilots took photographs from an aircraft for reconnaissance purposes. In the 30s. XX century aerial photography has replaced ground surveying and has become the main method for creating maps. By the mid-50s. with the help of aerial photographs, topographic maps of the entire territory of our country were compiled in 1: 100,000, and a quarter of a century later, a huge work was completed on creating a map at a scale of 1:25 000, consisting of 300 thousand sheets. The appearance in these years of colored aerial photographs contributed to the fact that they began to be widely used for studying rocks, soils, compiling geological, soil, geobotanical maps, studying the relationship between natural components, and conducting comprehensive geographical research.
After the launch of artificial earth satellites and spacecraft in 1957, geographers and cartographers received new materials for their work - space images. It turned out that even from a distance of thousands of kilometers, it is possible to take pictures that reflect many details of the earth's surface, and such a survey is sometimes more profitable than aerial photography. After all, one space image replaces thousands of aerial photographs. The satellite flies over areas that are inaccessible even for an airplane - the highest peaks, icy expanses. A satellite constantly operating in orbit can repeat the survey from day to day to observe rapidly changing,. In short, the shooting capabilities have expanded significantly. To obtain images, they began to use not only cameras, but also such equipment that would allow transmitting an image to Earth via radio channels, for example, scanners. When scanning (from the English scan - "to trace sequentially, in parts"), the terrain is viewed in sections across the route line. Light signals arriving at the radiation receiver from each area are converted into electrical signals and transmitted through space communication channels to the Earth, where they are recorded as small elements of the future image - pixels, which means “picture element”. This side-to-side view yields a snapshot line, and the accumulation of lines along the flight path gradually forms a snapshot. The advantage of the scanner survey is its efficiency: you can get an image of the territory directly during the satellite flight over it. Another advantage of scanner shooting over photographic is the ability to see what is not visible to the eye, since scanners are sensitive to such radiation that neither the eye nor the film can perceive. The image taken by the camera and delivered to Earth contains so many image details that the human eye cannot see them, so the image is magnified. More details can be seen when zoomed in. In this case, the integrity of the image will not be violated, there will be no breaks on it, it will remain continuous. Photographs can be magnified 10 to 20 times.
Another thing is the image obtained by scanning and transmitted to the Earth via radio channels. Signals during this transmission refer to specific, usually rectangular areas of the terrain. When zoomed in, it will become clear that such a picture consists of many rectangular elements of the same size, inside which there are no details, and the tone of the image at the boundaries of the sections changes abruptly. This is a discrete image. Each pixel of the image corresponds to a number stored in the computer's memory that indicates its brightness. Such pictures are called digital. They are recorded on optical CDs and can be transmitted over telecommunication networks over the Internet. A continuous photographic image for processing on a computer must also be turned into a discrete digital one; this is done using laboratory computer scanners.