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123-416: When applied to processing of the reflected signal in remote sensing for topography , homodyne detection lacks the ability of heterodyne detection to determine the size of a static discontinuity in elevation between two locations. (If there is a path between the two locations with smoothly changing elevation, then homodyne detection may in principle be able to track the signal phase along the path if sampling

246-474: A "bitter river" ( Oceanus ), with seven islands arranged around it so as to form a seven-pointed star. The accompanying text mentions seven outer regions beyond the encircling ocean. The descriptions of five of them have survived. In contrast to the Imago Mundi , an earlier Babylonian world map dating back to the 9th century BC depicted Babylon as being further north from the center of the world, though it

369-402: A consequence of accessibility ." Geography is a branch of inquiry that focuses on spatial information on Earth. It is an extremely broad topic and can be broken down multiple ways. There have been several approaches to doing this spanning at least several centuries, including "four traditions of geography" and into distinct branches. The Four traditions of geography are often used to divide

492-694: A degree or two with electronic compasses. Compasses can measure not just azimuth (i. e. degrees to magnetic north), but also altitude (degrees above the horizon), since the magnetic field curves into the Earth at different angles at different latitudes. More exact orientations require gyroscopic-aided orientation , periodically realigned by different methods including navigation from stars or known benchmarks. The quality of remote sensing data consists of its spatial, spectral, radiometric and temporal resolutions. In order to create sensor-based maps, most remote sensing systems expect to extrapolate sensor data in relation to

615-526: A focus on space, place, time, and scale. Today, geography is an extremely broad discipline with multiple approaches and modalities. There have been multiple attempts to organize the discipline, including the four traditions of geography, and into branches. Techniques employed can generally be broken down into quantitative and qualitative approaches, with many studies taking mixed-methods approaches. Common techniques include cartography , remote sensing , interviews , and surveying . Geography

738-418: A geographic information system). Remote sensing aids in land use, land cover (LULC) mapping, by helping to determine both what is naturally occurring on a piece of land and what human activities are taking place on it. Geostatistics deal with quantitative data analysis, specifically the application of a statistical methodology to the exploration of geographic phenomena. Geostatistics is used extensively in

861-554: A great deal of data handling overhead. These data tend to be generally more useful for many applications. The regular spatial and temporal organization of Level 3 datasets makes it feasible to readily combine data from different sources. While these processing levels are particularly suitable for typical satellite data processing pipelines, other data level vocabularies have been defined and may be appropriate for more heterogeneous workflows. Satellite images provide very useful information to produce statistics on topics closely related to

984-610: A high level of information for Ptolemy to construct detailed atlases . He extended the work of Hipparchus , using a grid system on his maps and adopting a length of 56.5 miles for a degree. From the 3rd century onwards, Chinese methods of geographical study and writing of geographical literature became much more comprehensive than what was found in Europe at the time (until the 13th century). Chinese geographers such as Liu An , Pei Xiu , Jia Dan , Shen Kuo , Fan Chengda , Zhou Daguan , and Xu Xiake wrote important treatises, yet by

1107-493: A history, they also exist in space and have a geography. For something to exist in the realm of geography, it must be able to be described spatially. Thus, space is the most fundamental concept at the foundation of geography. The concept is so basic, that geographers often have difficulty defining exactly what it is. Absolute space is the exact site, or spatial coordinates, of objects, persons, places, or phenomena under investigation. We exist in space. Absolute space leads to

1230-825: A large extent of geography. At the same time, the data is often complex to interpret, and bulky to store. Modern systems tend to store the data digitally, often with lossless compression . The difficulty with this approach is that the data is fragile, the format may be archaic, and the data may be easy to falsify. One of the best systems for archiving data series is as computer-generated machine-readable ultrafiche , usually in typefonts such as OCR-B , or as digitized half-tone images. Ultrafiches survive well in standard libraries, with lifetimes of several centuries. They can be created, copied, filed and retrieved by automated systems. They are about as compact as archival magnetic media, and yet can be read by human beings with minimal, standardized equipment. Generally speaking, remote sensing works on

1353-484: A legend of mapped classes that suits our purpose, taking again the example of wheat. The straightforward approach is counting the number of pixels classified as wheat and multiplying by the area of each pixel. Many authors have noticed that estimator is that it is generally biased because commission and omission errors in a confusion matrix do not compensate each other The main strength of classified satellite images or other indicators computed on satellite images

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1476-565: A product with greater information than a two-dimensional image of places, names, and topography. This approach offers more inclusive strategies than more traditional cartographic approaches for connecting the complex layers that makeup places. Ethnographical research techniques are used by human geographers. In cultural geography , there is a tradition of employing qualitative research techniques, also used in anthropology and sociology. Participant observation and in-depth interviews provide human geographers with qualitative data. Geopoetics

1599-472: A reference point including distances between known points on the ground. This depends on the type of sensor used. For example, in conventional photographs, distances are accurate in the center of the image, with the distortion of measurements increasing the farther you get from the center. Another factor is that of the platen against which the film is pressed can cause severe errors when photographs are used to measure ground distances. The step in which this problem

1722-679: A sample with less accurate, but exhaustive, data for a covariable or proxy that is cheaper to collect. For agricultural statistics, field surveys are usually required, while photo-interpretation may better for land cover classes that can be reliably identified on aerial photographs or high resolution satellite images. Additional uncertainty can appear because of imperfect reference data (ground truth or similar). Some options are: ratio estimator , regression estimator , calibration estimators and small area estimators If we target other variables, such as crop yield or leaf area , we may need different indicators to be computed from images, such as

1845-479: A single person from a single location. The European Age of Discovery during the 16th and the 17th centuries, where many new lands were discovered and accounts by European explorers such as Christopher Columbus , Marco Polo , and James Cook revived a desire for both accurate geographic detail and more solid theoretical foundations in Europe. In 1650, the first edition of the Geographia Generalis

1968-434: A structured or semi-structured approach during interviews involving specific questions or discussion points when utilized for research purposes. These questions are designed to extract focused information about the research topic while being flexible enough to allow participants to express their experiences and viewpoints, such as through open-ended questions. The concept of geography is present in all cultures, and therefore

2091-439: A system. The amount of time an individual, or group of people, spends in a place will often shape their attachment and perspective to that place. Time constrains the possible paths that can be taken through space, given a starting point, possible routes, and rate of travel. Visualizing time over space is challenging in terms of cartography, and includes Space-Prism, advanced 3D geovisualizations, and animated maps . Scale in

2214-417: A variety of fields, including hydrology , geology, petroleum exploration, weather analysis, urban planning , logistics, and epidemiology . The mathematical basis for geostatistics derives from cluster analysis , linear discriminant analysis and non-parametric statistical tests , and a variety of other subjects. Applications of geostatistics rely heavily on geographic information systems , particularly for

2337-558: Is a systematic study of the Earth (other celestial bodies are specified, such as "geography of Mars", or given another name, such as areography in the case of Mars), its features, and phenomena that take place on it. For something to fall into the domain of geography, it generally needs some sort of spatial component that can be placed on a map , such as coordinates , place names, or addresses . This has led to geography being associated with cartography and place names. Although many geographers are trained in toponymy and cartology, this

2460-750: Is an interdisciplinary approach that combines geography and poetry to explore the interconnectedness between humans, space, place, and the environment. Geopoetics is employed as a mixed methods tool to explain the implications of geographic research. It is often employed to address and communicate the implications of complex topics, such as the anthropocene . Geographers employ interviews to gather data and acquire valuable understandings from individuals or groups regarding their encounters, outlooks, and opinions concerning spatial phenomena. Interviews can be carried out through various mediums, including face-to-face interactions, phone conversations, online platforms, or written exchanges. Geographers typically adopt

2583-436: Is an ongoing source of debate in geography and is unlikely to be resolved anytime soon. Several laws have been proposed, and Tobler's first law of geography is the most generally accepted in geography. Some have argued that geographic laws do not need to be numbered. The existence of a first invites a second, and many have proposed themselves as that. It has also been proposed that Tobler's first law of geography should be moved to

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2706-458: Is balanced homodyne detection (BHD) using a positive–intrinsic–negative ( PIN ) diode. Remote sensing This is an accepted version of this page Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation . The term is applied especially to acquiring information about Earth and other planets . Remote sensing

2829-414: Is concerned with the study of processes and patterns in the natural environment like the atmosphere , hydrosphere , biosphere , and geosphere . Technical geography is interested in studying and applying techniques and methods to store, process, analyze, visualize, and use spatial data. It is the newest of the branches, the most controversial, and often other terms are used in the literature to describe

2952-479: Is credited to Hipparchus . He employed a sexagesimal system that was derived from Babylonian mathematics . The meridians were subdivided into 360°, with each degree further subdivided into 60 ( minutes ). To measure the longitude at different locations on Earth, he suggested using eclipses to determine the relative difference in time. The extensive mapping by the Romans as they explored new lands would later provide

3075-400: Is dense enough). Homodyne detection is more readily applicable to velocity sensing. In optical interferometry , homodyne signifies that the reference radiation (i.e. the local oscillator ) is derived from the same source as the signal before the modulating process . For example, in a laser scattering measurement, the laser beam is split into two parts. One is the local oscillator and

3198-469: Is impacted by all other locations on Earth. In one of Yi-Fu Tuan 's papers, he explains that in his view, geography is the study of Earth as a home for humanity, and thus place and the complex meaning behind the term is central to the discipline of geography. Time is usually thought to be within the domain of history , however, it is of significant concern in the discipline of geography. In physics, space and time are not separated, and are combined into

3321-604: Is impossible to directly measure temperatures in the upper atmosphere, it is possible to measure the spectral emissions from a known chemical species (such as carbon dioxide) in that region. The frequency of the emissions may then be related via thermodynamics to the temperature in that region. To facilitate the discussion of data processing in practice, several processing "levels" were first defined in 1986 by NASA as part of its Earth Observing System and steadily adopted since then, both internally at NASA (e. g., ) and elsewhere (e. g., ); these definitions are: A Level 1 data record

3444-417: Is not certain what that center was supposed to represent. The ideas of Anaximander (c. 610–545 BC): considered by later Greek writers to be the true founder of geography, come to us through fragments quoted by his successors. Anaximander is credited with the invention of the gnomon , the simple, yet efficient Greek instrument that allowed the early measurement of latitude . Thales is also credited with

3567-438: Is not their main preoccupation. Geographers study the Earth's spatial and temporal distribution of phenomena, processes, and features as well as the interaction of humans and their environment . Because space and place affect a variety of topics, such as economics, health, climate , plants, and animals, geography is highly interdisciplinary. The interdisciplinary nature of the geographical approach depends on an attentiveness to

3690-535: Is one of the broadest, is consistent with the naming convention of the other two branches, has been in use since the 1700s, and has been used by the UNESCO Encyclopedia of Life Support Systems to divide geography into themes. As academic fields increasingly specialize in their nature, technical geography has emerged as a branch of geography specializing in geographic methods and thought. The emergence of technical geography has brought new relevance to

3813-418: Is providing cheap information on the whole target area or most of it. This information usually has a good correlation with the target variable (ground truth) that is usually expensive to observe in an unbiased and accurate way. Therefore it can be observed on a probabilistic sample selected on an area sampling frame . Traditional survey methodology provides different methods to combine accurate information on

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3936-454: Is related to everything else, but near things are more related than distant things." As spatial interrelationships are key to this synoptic science, maps are a key tool. Classical cartography has been joined by a more modern approach to geographical analysis, computer-based geographic information systems (GIS). In their study, geographers use four interrelated approaches: Quantitative methods in geography became particularly influential in

4059-450: Is relevant to highlight that probabilistic sampling is not critical for the selection of training pixels for image classification, but it is necessary for accuracy assessment of the classified images and area estimation. Additional care is recommended to ensure that training and validation datasets are not spatially correlated. We suppose now that we have classified images or a land cover map produced by visual photo-interpretation, with

4182-432: Is resolved is called georeferencing and involves computer-aided matching of points in the image (typically 30 or more points per image) which is extrapolated with the use of an established benchmark, "warping" the image to produce accurate spatial data. As of the early 1990s, most satellite images are sold fully georeferenced. In addition, images may need to be radiometrically and atmospherically corrected. Interpretation

4305-430: Is spherical in shape, with the credit going either to Parmenides or Pythagoras . Anaxagoras was able to demonstrate that the profile of the Earth was circular by explaining eclipses . However, he still believed that the Earth was a flat disk, as did many of his contemporaries. One of the first estimates of the radius of the Earth was made by Eratosthenes . The first rigorous system of latitude and longitude lines

4428-489: Is that of examined areas or objects that reflect or emit radiation that stand out from surrounding areas. For a summary of major remote sensing satellite systems see the overview table. To coordinate a series of large-scale observations, most sensing systems depend on the following: platform location and the orientation of the sensor. High-end instruments now often use positional information from satellite navigation systems . The rotation and orientation are often provided within

4551-402: Is that of increasingly smaller sensor pods such as those used by law enforcement and the military, in both manned and unmanned platforms. The advantage of this approach is that this requires minimal modification to a given airframe. Later imaging technologies would include infrared, conventional, Doppler and synthetic aperture radar. The development of artificial satellites in the latter half of

4674-440: Is the critical process of making sense of the data. The first application was that of aerial photographic collection which used the following process; spatial measurement through the use of a light table in both conventional single or stereographic coverage, added skills such as the use of photogrammetry, the use of photomosaics, repeat coverage, Making use of objects' known dimensions in order to detect modifications. Image Analysis

4797-560: Is the most fundamental (i. e., highest reversible level) data record that has significant scientific utility, and is the foundation upon which all subsequent data sets are produced. Level 2 is the first level that is directly usable for most scientific applications; its value is much greater than the lower levels. Level 2 data sets tend to be less voluminous than Level 1 data because they have been reduced temporally, spatially, or spectrally. Level 3 data sets are generally smaller than lower level data sets and thus can be dealt with without incurring

4920-424: Is the recently developed automated computer-aided application that is in increasing use. Object-Based Image Analysis (OBIA) is a sub-discipline of GIScience devoted to partitioning remote sensing (RS) imagery into meaningful image-objects, and assessing their characteristics through spatial, spectral and temporal scale. Old data from remote sensing is often valuable because it may provide the only long-term data for

5043-536: Is the study of earth's seasons, climate , atmosphere , soil , streams, landforms, and oceans. Physical geographers will often work in identifying and monitoring the use of natural resources. Human geography (or anthropogeography) is a branch of geography that focuses on studying patterns and processes that shape human society. It encompasses the human, political, cultural , social, and economic aspects. In industry, human geographers often work in city planning, public health, or business analysis. Various approaches to

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5166-542: Is the study of the lands, features, inhabitants, and phenomena of Earth . Geography is an all-encompassing discipline that seeks an understanding of Earth and its human and natural complexities —not merely where objects are, but also how they have changed and come to be. While geography is specific to Earth, many concepts can be applied more broadly to other celestial bodies in the field of planetary science . Geography has been called "a bridge between natural science and social science disciplines." Origins of many of

5289-410: Is used in numerous fields, including geophysics , geography , land surveying and most Earth science disciplines (e.g. exploration geophysics , hydrology , ecology , meteorology , oceanography , glaciology , geology ). It also has military, intelligence, commercial, economic, planning, and humanitarian applications, among others. In current usage, the term remote sensing generally refers to

5412-613: The Amazon Basin , glacial features in Arctic and Antarctic regions, and depth sounding of coastal and ocean depths. Military collection during the Cold War made use of stand-off collection of data about dangerous border areas. Remote sensing also replaces costly and slow data collection on the ground, ensuring in the process that areas or objects are not disturbed. Orbital platforms collect and transmit data from different parts of

5535-1023: The EGU or Digital Earth encourage the development of learning modules and learning portals . Examples include: FIS – Remote Sensing in School Lessons , Geospektiv , Ychange , or Spatial Discovery, to promote media and method qualifications as well as independent learning. Remote sensing data are processed and analyzed with computer software, known as a remote sensing application . A large number of proprietary and open source applications exist to process remote sensing data. There are applications of gamma rays to mineral exploration through remote sensing. In 1972 more than two million dollars were spent on remote sensing applications with gamma rays to mineral exploration. Gamma rays are used to search for deposits of uranium. By observing radioactivity from potassium, porphyry copper deposits can be located. A high ratio of uranium to thorium has been found to be related to

5658-569: The Earth radius was only 16.8 km less than the modern value of 6,356.7 km. In contrast to his predecessors, who measured the Earth's circumference by sighting the Sun simultaneously from two different locations, al-Biruni developed a new method of using trigonometric calculations based on the angle between a plain and mountain top, which yielded more accurate measurements of the Earth's circumference, and made it possible for it to be measured by

5781-556: The European Commission . Forest area and deforestation estimation have also been a frequent target of remote sensing projects, the same as land cover and land use Ground truth or reference data to train and validate image classification require a field survey if we are targetting annual crops or individual forest species, but may be substituted by photointerpretation if we look at wider classes that can be reliably identified on aerial photos or satellite images. It

5904-579: The Magellan spacecraft provided detailed topographic maps of Venus , while instruments aboard SOHO allowed studies to be performed on the Sun and the solar wind , just to name a few examples. Recent developments include, beginning in the 1960s and 1970s, the development of image processing of satellite imagery . The use of the term "remote sensing" began in the early 1960s when Evelyn Pruitt realized that advances in science meant that aerial photography

6027-536: The MetOp spacecraft of EUMETSAT are all operated at altitudes of about 800 km (500 mi). The Proba-1 , Proba-2 and SMOS spacecraft of European Space Agency are observing the Earth from an altitude of about 700 km (430 mi). The Earth observation satellites of UAE, DubaiSat-1 & DubaiSat-2 are also placed in Low Earth orbits (LEO) orbits and providing satellite imagery of various parts of

6150-537: The NDVI , a good proxy to chlorophyll activity. The modern discipline of remote sensing arose with the development of flight. The balloonist G. Tournachon (alias Nadar ) made photographs of Paris from his balloon in 1858. Messenger pigeons, kites, rockets and unmanned balloons were also used for early images. With the exception of balloons, these first, individual images were not particularly useful for map making or for scientific purposes. Systematic aerial photography

6273-528: The National Council for Geographic Education and the Association of American Geographers in 1984. These themes are Location, place, relationships within places (often summarized as Human-Environment Interaction), movement, and regions. The five themes of geography have shaped how American education approaches the topic in the years since. Just as all phenomena exist in time and thus have

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6396-628: The Royal Danish Geographical Society in 1876 and the National Geographic Society in 1888. The influence of Immanuel Kant , Alexander von Humboldt , Carl Ritter , and Paul Vidal de la Blache can be seen as a major turning point in geography from philosophy to an academic subject. Geographers such as Richard Hartshorne and Joseph Kerski have regarded both Humboldt and Ritter as the founders of modern geography, as Humboldt and Ritter were

6519-664: The Spatial or Locational Tradition, the Man-Land or Human-Environment Interaction Tradition (sometimes referred to as Integrated geography ), the Area Studies or Regional Tradition, and the Earth Science Tradition. These concepts are broad sets of geography philosophies bound together within the discipline. They are one of many ways geographers organize the major sets of thoughts and philosophies within

6642-472: The built environment and how humans create, view, manage, and influence space. Physical geography examines the natural environment and how organisms , climate, soil , water, and landforms produce and interact. The difference between these approaches led to the development of integrated geography , which combines physical and human geography and concerns the interactions between the environment and humans. Technical geography involves studying and developing

6765-615: The electromagnetic spectrum , which in conjunction with larger scale aerial or ground-based sensing and analysis, provides researchers with enough information to monitor trends such as El Niño and other natural long and short term phenomena. Other uses include different areas of the earth sciences such as natural resource management , agricultural fields such as land usage and conservation, greenhouse gas monitoring , oil spill detection and monitoring, and national security and overhead, ground-based and stand-off collection on border areas. The basis for multispectral collection and analysis

6888-470: The first law of geography , "everything is related to everything else, but near things are more related than distant things." This law summarizes the first assumption geographers make about the world. The discipline of geography, especially physical geography, and geology have significant overlap. In the past, the two have often shared academic departments at universities, a point that has led to conflict over resources. Both disciplines do seek to understand

7011-607: The interpolation (estimate) of unmeasured points. Geographers are making notable contributions to the method of quantitative techniques. Qualitative methods in geography are descriptive rather than numerical or statistical in nature. They add context to concepts, and explore human concepts like beliefs and perspective that are difficult or impossible to quantify. Human geography is much more likely to employ qualitative methods than physical geography. Increasingly, technical geographers are attempting to employ GIS methods to qualitative datasets. Qualitative cartography employs many of

7134-452: The lithosphere , atmosphere , hydrosphere , and biosphere . Places do not exist in a vacuum and instead have complex spatial relationships with each other, and place is concerned how a location is situated in relation to all other locations. As a discipline then, the term place in geography includes all spatial phenomena occurring at a location, the diverse uses and meanings humans ascribe to that location, and how that location impacts and

7257-506: The quantitative revolution , and critical geography . The strong interdisciplinary links between geography and the sciences of geology and botany , as well as economics, sociology, and demographics , have also grown greatly, especially as a result of earth system science that seeks to understand the world in a holistic view. New concepts and philosophies have emerged from the rapid advancement of computers, quantitative methods, and interdisciplinary approaches. In 1970, Waldo Tobler proposed

7380-546: The rocks on the Earth's surface and the processes that change them over time. Geology employs many of the tools and techniques of technical geographers, such as GIS and remote sensing to aid in geological mapping . However, geology includes research that goes beyond the spatial component, such as the chemical analysis of rocks and biogeochemistry . The discipline of History has significant overlap with geography, especially human geography. Like geology, history and geography have shared university departments. Geography provides

7503-461: The "Balkhī school" of terrestrial mapping in Baghdad . Suhrāb, a late tenth century Muslim geographer accompanied a book of geographical coordinates, with instructions for making a rectangular world map with equirectangular projection or cylindrical equidistant projection. Abu Rayhan Biruni (976–1048) first described a polar equi- azimuthal equidistant projection of the celestial sphere . He

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7626-714: The 17th century advanced ideas and methods of Western-style geography were adopted in China. During the Middle Ages , the fall of the Roman empire led to a shift in the evolution of geography from Europe to the Islamic world . Muslim geographers such as Muhammad al-Idrisi produced detailed world maps (such as Tabula Rogeriana ), while other geographers such as Yaqut al-Hamawi , Abu Rayhan Biruni , Ibn Battuta , and Ibn Khaldun provided detailed accounts of their journeys and

7749-622: The 20th century allowed remote sensing to progress to a global scale as of the end of the Cold War. Instrumentation aboard various Earth observing and weather satellites such as Landsat , the Nimbus and more recent missions such as RADARSAT and UARS provided global measurements of various data for civil, research, and military purposes. Space probes to other planets have also provided the opportunity to conduct remote sensing studies in extraterrestrial environments, synthetic aperture radar aboard

7872-470: The Earth for automatic retrieval by a computer in an accurate manner appropriate to the information's purpose. In addition to all of the other subdisciplines of geography, GIS specialists must understand computer science and database systems. GIS has revolutionized the field of cartography: nearly all mapmaking is now done with the assistance of some form of GIS software . The science of using GIS software and GIS techniques to represent, analyse, and predict

7995-493: The Earth most effectively and behavioural psychology to induce the readers of their maps to act on the information. They must learn geodesy and fairly advanced mathematics to understand how the shape of the Earth affects the distortion of map symbols projected onto a flat surface for viewing. It can be said, without much controversy, that cartography is the seed from which the larger field of geography grew. Geographic information systems (GIS) deal with storing information about

8118-529: The Earth's land surface , ocean, and atmosphere, because it: (a) supplies objective information at a variety of spatial scales (local to global), (b) provides a synoptic view of the area of interest, (c) allows access to distant and inaccessible sites, (d) provides spectral information outside the visible portion of the electromagnetic spectrum , and (e) facilitates studies of how features/areas change over time. Remotely sensed data may be analyzed independently or in conjunction with other digital data layers (e.g., in

8241-424: The Earth's surface, the activity and use that occurs, has occurred, and will occur at the coordinates, and the meaning ascribed to the space by human individuals and groups. This can be extraordinarily complex, as different spaces may have different uses at different times and mean different things to different people. In physical geography, a place includes all of the physical phenomena that occur in space, including

8364-600: The Earth. To get global coverage with a low orbit, a polar orbit is used. A low orbit will have an orbital period of roughly 100 minutes and the Earth will rotate around its polar axis about 25° between successive orbits. The ground track moves towards the west 25° each orbit, allowing a different section of the globe to be scanned with each orbit. Most are in Sun-synchronous orbits . Geography Geography (from Ancient Greek γεωγραφία geōgraphía ; combining gê 'Earth' and gráphō 'write')

8487-478: The German students use the services of Google Earth ; in 2006 alone the software was downloaded 100 million times. But studies have shown that only a fraction of them know more about the data they are working with. There exists a huge knowledge gap between the application and the understanding of satellite images. Remote sensing only plays a tangential role in schools, regardless of the political claims to strengthen

8610-507: The art, science, and technology of making maps. Cartographers study the Earth's surface representation with abstract symbols (map making). Although other subdisciplines of geography rely on maps for presenting their analyses, the actual making of maps is abstract enough to be regarded separately. Cartography has grown from a collection of drafting techniques into an actual science. Cartographers must learn cognitive psychology and ergonomics to understand which symbols convey information about

8733-458: The book expanded on these key concepts by adding "Environmental systems," "Social Systems," "Nature," " Globalization ," "Development," and "Risk," demonstrating how challenging narrowing the field can be. Another approach used extensively in teaching geography are the Five themes of geography established by "Guidelines for Geographic Education: Elementary and Secondary Schools," published jointly by

8856-406: The broad discipline of geography by serving as a set of unique methods for managing the interdisciplinary nature of the phenomena under investigation. While human and physical geographers use the techniques employed by technical geographers, technical geography is more concerned with the fundamental spatial concepts and technologies than the nature of the data. It is therefore closely associated with

8979-438: The concept of spacetime . Geography is subject to the laws of physics, and in studying things that occur in space, time must be considered. Time in geography is more than just the historical record of events that occurred at various discrete coordinates; but also includes modeling the dynamic movement of people, organisms, and things through space. Time facilitates movement through space, ultimately allowing things to flow through

9102-424: The concepts in geography can be traced to Greek Eratosthenes of Cyrene, who may have coined the term "geographia" ( c.  276 BC  – c.  195/194 BC ). The first recorded use of the word γεωγραφία was as the title of a book by Greek scholar Claudius Ptolemy (100 – 170 AD). This work created the so-called "Ptolemaic tradition" of geography, which included "Ptolemaic cartographic theory." However,

9225-468: The concepts of geography (such as cartography ) date back to the earliest attempts to understand the world spatially, with the earliest example of an attempted world map dating to the 9th century BCE in ancient Babylon . The history of geography as a discipline spans cultures and millennia, being independently developed by multiple groups, and cross-pollinated by trade between these groups. The core concepts of geography consistent between all approaches are

9348-405: The context of a map is the ratio between a distance measured on the map and the corresponding distance as measured on the ground. This concept is fundamental to the discipline of geography, not just cartography, in that phenomena being investigated appear different depending on the scale used. Scale is the frame that geographers use to measure space, and ultimately to understand a place. During

9471-452: The different historical approach theories geographers have taken to the discipline. In contrast, geography's branches describe contemporary applied geographical approaches. Geography is an extremely broad field. Because of this, many view the various definitions of geography proposed over the decades as inadequate. To address this, William D. Pattison proposed the concept of the "Four traditions of Geography" in 1964. These traditions are

9594-399: The discipline during the quantitative revolution of the 1950s and 60s. These methods revitalized the discipline in many ways, allowing scientific testing of hypotheses and proposing scientific geographic theories and laws. The quantitative revolution heavily influenced and revitalized technical geography, and lead to the development of the subfield of quantitative geography. Cartography is

9717-514: The discipline into a section containing content such as cartographic techniques and globes. There are several other terms, often used interchangeably with technical geography to subdivide the discipline, including "techniques of geographic analysis," "Geographic Information Technology," "Geography method's and techniques," " Geographic Information Science ," " geoinformatics ," " geomatics ," and "information geography". There are subtle differences to each concept and term; however, technical geography

9840-518: The discipline of geography is normally concerned with the Earth, the term can also be informally used to describe the study of other worlds, such as the planets of the Solar System and even beyond. The study of systems larger than the Earth itself usually forms part of Astronomy or Cosmology . The study of other planets is usually called planetary science . Alternative terms such as areography (geography of Mars) have been employed to describe

9963-552: The discipline. In another approach to the abovementioned four traditions, geography is organized into applied branches. The UNESCO Encyclopedia of Life Support Systems organizes geography into the three categories of human geography , physical geography , and technical geography . Some publications limit the number of branches to physical and human, describing them as the principal branches. Geographers rarely focus on just one of these topics, often using one as their primary focus and then incorporating data and methods from

10086-495: The discovery of the Earth's Van Allen radiation belts . The TIROS-1 spacecraft, launched on April 1, 1960, as part of NASA's Television Infrared Observation Satellite (TIROS) program, sent back the first television footage of weather patterns to be taken from space. In 2008, more than 150 Earth observation satellites were in orbit, recording data with both passive and active sensors and acquiring more than 10 terabits of data daily. By 2021, that total had grown to over 950, with

10209-407: The emerging category. These branches use similar geographic philosophies, concepts, and tools and often overlap significantly. Physical geography (or physiography) focuses on geography as an Earth science . It aims to understand the physical problems and the issues of lithosphere , hydrosphere , atmosphere , pedosphere , and global flora and fauna patterns ( biosphere ). Physical geography

10332-642: The farmer who plants his fields in a remote corner of the country knows its value." The development of remote sensing technology reached a climax during the Cold War with the use of modified combat aircraft such as the P-51 , P-38 , RB-66 and the F-4C , or specifically designed collection platforms such as the U2/TR-1 , SR-71 , A-5 and the OV-1 series both in overhead and stand-off collection. A more recent development

10455-417: The fields of media and methods apart from the mere visual interpretation of satellite images. Many teachers have great interest in the subject "remote sensing", being motivated to integrate this topic into teaching, provided that the curriculum is considered. In many cases, this encouragement fails because of confusing information. In order to integrate remote sensing in a sustainable manner organizations like

10578-581: The first commercial satellite (IKONOS) collecting very high resolution imagery was launched. Remote Sensing has a growing relevance in the modern information society. It represents a key technology as part of the aerospace industry and bears increasing economic relevance – new sensors e.g. TerraSAR-X and RapidEye are developed constantly and the demand for skilled labour is increasing steadily. Furthermore, remote sensing exceedingly influences everyday life, ranging from weather forecasts to reports on climate change or natural disasters . As an example, 80% of

10701-518: The first to establish geography as an independent scientific discipline. Over the past two centuries, the advancements in technology with computers have led to the development of geomatics and new practices such as participant observation and geostatistics being incorporated into geography's portfolio of tools. In the West during the 20th century, the discipline of geography went through four major phases: environmental determinism , regional geography ,

10824-504: The geography of the regions they visited. Turkish geographer Mahmud al-Kashgari drew a world map on a linguistic basis, and later so did Piri Reis ( Piri Reis map ). Further, Islamic scholars translated and interpreted the earlier works of the Romans and the Greeks and established the House of Wisdom in Baghdad for this purpose. Abū Zayd al-Balkhī , originally from Balkh , founded

10947-449: The heights of mountains, depths of the valleys , and expanse of the horizon . He also discussed human geography and the planetary habitability of the Earth. He also calculated the latitude of Kath, Khwarezm , using the maximum altitude of the Sun, and solved a complex geodesic equation to accurately compute the Earth's circumference , which was close to modern values of the Earth's circumference. His estimate of 6,339.9 km for

11070-600: The history of the discipline is a series of competing narratives, with concepts emerging at various points across space and time. The oldest known world maps date back to ancient Babylon from the 9th century BC. The best known Babylonian world map, however, is the Imago Mundi of 600 BC. The map as reconstructed by Eckhard Unger shows Babylon on the Euphrates , surrounded by a circular landmass showing Assyria , Urartu , and several cities, in turn surrounded by

11193-401: The intensity of the laser.. The generated current signal from the photodetector is often too weak to measure. It is therefore converted into a voltage using a Transimpedance amplifier . In radio technology, the distinction is not the source of the local oscillator, but the frequency used. In heterodyne detection, the local oscillator is frequency-shifted, while in homodyne detection it has

11316-461: The largest number of satellites operated by US-based company Planet Labs . Most Earth observation satellites carry instruments that should be operated at a relatively low altitude. Most orbit at altitudes above 500 to 600 kilometers (310 to 370 mi). Lower orbits have significant air-drag , which makes frequent orbit reboost maneuvers necessary. The Earth observation satellites ERS-1, ERS-2 and Envisat of European Space Agency as well as

11439-465: The launch of the first artificial satellite, Sputnik 1 , by the Soviet Union on October 4, 1957. Sputnik 1 sent back radio signals, which scientists used to study the ionosphere . The United States Army Ballistic Missile Agency launched the first American satellite, Explorer 1 , for NASA's Jet Propulsion Laboratory on January 31, 1958. The information sent back from its radiation detector led to

11562-402: The laws of nature and to mark their influences upon man. This is 'a description of the world'—that is Geography. In a word, Geography is a Science—a thing not of mere names but of argument and reason, of cause and effect. Geography as a discipline can be split broadly into three main branches: human geography , physical geography , and technical geography . Human geography largely focuses on

11685-414: The other branches. Often, geographers are asked to describe what they do by individuals outside the discipline and are likely to identify closely with a specific branch, or sub-branch when describing themselves to lay people. Human geography studies people and their communities, cultures, economies, and environmental interactions by studying their relations with and across space and place. Physical geography

11808-522: The other hand, emits energy in order to scan objects and areas whereupon a sensor then detects and measures the radiation that is reflected or backscattered from the target. RADAR and LiDAR are examples of active remote sensing where the time delay between emission and return is measured, establishing the location, speed and direction of an object. Remote sensing makes it possible to collect data of dangerous or inaccessible areas. Remote sensing applications include monitoring deforestation in areas such as

11931-463: The other is sent to the system to be probed. The scattered light is then mixed with the local oscillator on the detector. This arrangement has the advantage of being insensitive to fluctuations in the frequency of the laser. Usually the scattered beam will be weak, in which case the (nearly) steady component of the detector output is a good measure of the instantaneous local oscillator intensity and therefore can be used to compensate for any fluctuations in

12054-562: The possibility of providing a room temperature quantum sensor with continuous-variable quantum information . However, challenges include reducing noise, increasing bandwidth and improving the integration of electronic and photonic components. Recently, these challenges have been overcome to demonstrate a free-space-coupled room temperature quantum sensor with large-scale integrated photonics and electronics. An encrypted secure communication system can be based on quantum key distribution (QKD). An efficient receiver scheme for implementing QKD

12177-402: The prediction of eclipses. The foundations of geography can be traced to ancient cultures, such as the ancient, medieval, and early modern Chinese . The Greeks , who were the first to explore geography as both art and science, achieved this through Cartography , Philosophy , and Literature , or through Mathematics . There is some debate about who was the first person to assert that the Earth

12300-852: The presence of hydrothermal copper deposits. Radiation patterns have also been known to occur above oil and gas fields, but some of these patterns were thought to be due to surface soils instead of oil and gas. An Earth observation satellite or Earth remote sensing satellite is a satellite used or designed for Earth observation (EO) from orbit , including spy satellites and similar ones intended for non-military uses such as environmental monitoring , meteorology , cartography and others. The most common type are Earth imaging satellites, that take satellite images , analogous to aerial photographs ; some EO satellites may perform remote sensing without forming pictures, such as in GNSS radio occultation . The first occurrence of satellite remote sensing can be dated to

12423-412: The principle of the inverse problem : while the object or phenomenon of interest (the state ) may not be directly measured, there exists some other variable that can be detected and measured (the observation ) which may be related to the object of interest through a calculation. The common analogy given to describe this is trying to determine the type of animal from its footprints. For example, while it

12546-462: The processing of signals in some applications of magnetic resonance imaging , homodyne detection can offer advantages over magnitude detection. The homodyne technique can suppress excessive noise and undesired quadrature components (90° out-of-phase), and provide stable access to information that may be encoded into the phase or polarity of images. Homodyne detection was one of the key techniques in demonstrating quantum entanglement . This has led to

12669-457: The quantitative revolution, geography shifted to an empirical law-making ( nomothetic ) approach. Several laws of geography have been proposed since then, most notably by Waldo Tobler and can be viewed as a product of the quantitative revolution. In general, some dispute the entire concept of laws in geography and the social sciences. These criticisms have been addressed by Tobler and others, such as Michael Frank Goodchild . However, this

12792-500: The reflection of sunlight is detected by the sensor). Remote sensing can be divided into two types of methods: Passive remote sensing and Active remote sensing. Passive sensors gather radiation that is emitted or reflected by the object or surrounding areas. Reflected sunlight is the most common source of radiation measured by passive sensors. Examples of passive remote sensors include film photography , infrared , charge-coupled devices , and radiometers . Active collection, on

12915-473: The relationship between physical and human phenomena and their spatial patterns. Names of places...are not geography...To know by heart a whole gazetteer full of them would not, in itself, constitute anyone a geographer. Geography has higher aims than this: it seeks to classify phenomena (alike of the natural and of the political world, in so far as it treats of the latter), to compare, to generalize, to ascend from effects to causes, and, in doing so, to trace out

13038-546: The same frequency as the radiation to be detected. See direct conversion receiver . Lock-in amplifiers are homodyne detectors integrated into measurement equipment or packaged as stand-alone laboratory equipment for sensitive detection and highly selective filtering of weak or noisy signals. Homodyne/lock-in detection has been one of the most commonly used signal processing methods across a wide range of experimental disciplines for decades. Homodyne and heterodyne techniques are commonly used in thermoreflectance techniques. In

13161-438: The same software and techniques as quantitative cartography. It may be employed to inform on map practices, or to visualize perspectives and ideas that are not strictly quantitative in nature. An example of a form of qualitative cartography is a Chorochromatic map of nominal data, such as land cover or dominant language group in an area. Another example is a deep map , or maps that combine geography and storytelling to produce

13284-533: The second and replaced with another. A few of the proposed laws of geography are below: Additionally, several variations or amendments to these laws exist within the literature, although not as well supported. For example, one paper proposed an amended version of Tobler's first law of geography, referred to in the text as the Tobler–von Thünen law , which states: "Everything is related to everything else, but near things are more related than distant things, as

13407-445: The spatial context within which historical events unfold. The physical geographic features of a region, such as its landforms, climate, and resources, shape human settlements, trade routes, and economic activities, which in turn influence the course of historical events. Thus, a historian must have a strong foundation in geography. Historians employ the techniques of technical geographers to create historical atlases and maps. While

13530-675: The spatial relationships is called geographic information science (GISc). Remote sensing is the art, science, and technology of obtaining information about Earth's features from measurements made at a distance. Remotely sensed data can be either passive, such as traditional photography , or active, such as LiDAR . A variety of platforms can be used for remote sensing, including satellite imagery , aerial photography (including consumer drones), and data obtained from hand-held sensors. Products from remote sensing include Digital elevation model and cartographic base maps. Geographers increasingly use remotely sensed data to obtain information about

13653-538: The spatial tradition of geography while being applied to the other two major branches. A technical geographer might work as a GIS analyst, a GIS developer working to make new software tools, or create general reference maps incorporating human and natural features. All geographic research and analysis start with asking the question "where," followed by "why there." Geographers start with the fundamental assumption set forth in Tobler's first law of geography , that "everything

13776-403: The study of human geography have also arisen through time and include: Technical geography concerns studying and developing tools, techniques, and statistical methods employed to collect, analyze, use, and understand spatial data. Technical geography is the most recently recognized, and controversial, of the branches. Its use dates back to 1749, when a book published by Edward Cave organized

13899-423: The support for teaching on the subject. A lot of the computer software explicitly developed for school lessons has not yet been implemented due to its complexity. Thereby, the subject is either not at all integrated into the curriculum or does not pass the step of an interpretation of analogue images. In fact, the subject of remote sensing requires a consolidation of physics and mathematics as well as competences in

14022-639: The territory, such as agriculture, forestry or land cover in general. The first large project to apply Landsata 1 images for statistics was LACIE (Large Area Crop Inventory Experiment), run by NASA, NOAA and the USDA in 1974–77. Many other application projects on crop area estimation have followed, including the Italian AGRIT project and the MARS project of the Joint Research Centre (JRC) of

14145-572: The times when geography became recognized as a discrete academic discipline , and became part of a typical university curriculum in Europe (especially Paris and Berlin ). The development of many geographic societies also occurred during the 19th century, with the foundations of the Société de Géographie in 1821, the Royal Geographical Society in 1830, Russian Geographical Society in 1845, American Geographical Society in 1851,

14268-494: The tools and techniques used by geographers, such as remote sensing, cartography, and geographic information system. Narrowing down geography to a few key concepts is extremely challenging, and subject to tremendous debate within the discipline. In one attempt, the 1st edition of the book "Key Concepts in Geography" broke down this into chapters focusing on "Space," "Place," "Time," "Scale," and "Landscape." The 2nd edition of

14391-422: The use of satellite - or aircraft-based sensor technologies to detect and classify objects on Earth. It includes the surface and the atmosphere and oceans , based on propagated signals (e.g. electromagnetic radiation ). It may be split into "active" remote sensing (when a signal is emitted by a satellite or aircraft to the object and its reflection is detected by the sensor) and "passive" remote sensing (when

14514-401: The view of the world as a photograph, with everything frozen in place when the coordinates were recorded. Today, geographers are trained to recognize the world as a dynamic space where all processes interact and take place, rather than a static image on a map. Place is one of the most complex and important terms in geography. In human geography, place is the synthesis of the coordinates on

14637-591: Was developed for military surveillance and reconnaissance purposes beginning in World War I . After WWI, remote sensing technology was quickly adapted to civilian applications. This is demonstrated by the first line of a 1941 textbook titled "Aerophotography and Aerosurverying," which stated the following: "There is no longer any need to preach for aerial photography-not in the United States- for so widespread has become its use and so great its value that even

14760-615: Was finding the latitude and longitude of a geographic location. While the problem of latitude was solved long ago, but that of longitude remained; agreeing on what zero meridians should be was only part of the problem. It was left to John Harrison to solve it by inventing the chronometer H-4 in 1760, and later in 1884 for the International Meridian Conference to adopt by convention the Greenwich meridian as zero meridians. The 18th and 19th centuries were

14883-559: Was no longer an adequate term to describe the data streams being generated by new technologies. With assistance from her fellow staff member at the Office of Naval Research, Walter Bailey, she coined the term "remote sensing". Several research groups in Silicon Valley including NASA Ames Research Center , GTE , and ESL Inc. developed Fourier transform techniques leading to the first notable enhancement of imagery data. In 1999

15006-551: Was published by Bernhardus Varenius , which was later edited and republished by others including Isaac Newton . This textbook sought to integrate new scientific discoveries and principles into classical geography and approach the discipline like the other sciences emerging, and is seen by some as the division between ancient and modern geography in the West. The Geographia Generalis contained both theoretical background and practical applications related to ship navigation. The remaining problem facing both explorers and geographers

15129-523: Was regarded as the most skilled when it came to mapping cities and measuring the distances between them, which he did for many cities in the Middle East and the Indian subcontinent . He often combined astronomical readings and mathematical equations to develop methods of pin-pointing locations by recording degrees of latitude and longitude . He also developed similar techniques when it came to measuring

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