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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.
A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, moon, or asteroid. A "global DEM" refers to a discrete global grid. DEMs are used often in geographic information systems (GIS), and are the most common basis for digitally produced relief maps. A digital terrain model (DTM) represents specifically the ground surface while DEM and DSM may represent tree top canopy or building roofs.
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 is used in numerous fields, including geophysics, geography, land surveying and most Earth science disciplines ; it also has military, intelligence, commercial, economic, planning, and humanitarian applications, among others.
The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat 1 in 1975. The most recent, Landsat 9, was launched on 27 September 2021.
The Blue Marble is an image of Earth taken on December 7, 1972, from a distance of around 29,000 kilometers from the planet's surface. Taken by the crew of the Apollo 17 spacecraft on its way to the Moon, it is one of the most reproduced images in history.
Landsat 7 is the seventh satellite of the Landsat program. Launched on 15 April 1999, Landsat 7's primary goal is to refresh the global archive of satellite photos, providing up-to-date and cloud-free images. The Landsat program is managed and operated by the United States Geological Survey, and data from Landsat 7 is collected and distributed by the USGS. The NASA WorldWind project allows 3D images from Landsat 7 and other sources to be freely navigated and viewed from any angle. The satellite's companion, Earth Observing-1, trailed by one minute and followed the same orbital characteristics, but in 2011 its fuel was depleted and EO-1's orbit began to degrade. Landsat 7 was built by Lockheed Martin Space Systems.
DigitalGlobe is an American commercial vendor of space imagery and geospatial content, and operator of civilian remote sensing spacecraft. The company went public on the New York Stock Exchange on 14 May 2009, selling 14.7 million shares at US$19.00 each to raise US$279 million in capital. On 5 October 2017, Maxar Technologies completed its acquisition of DigitalGlobe.
NASA WorldWind is an open-source virtual globe. According to the website, "WorldWind is an open source virtual globe API. WorldWind allows developers to quickly and easily create interactive visualizations of 3D globe, map and geographical information. Organizations around the world use WorldWind to monitor weather patterns, visualize cities and terrain, track vehicle movement, analyze geospatial data and educate humanity about the Earth." It was first developed by NASA in 2003 for use on personal computers and then further developed in concert with the open source community since 2004. As of 2017, a web-based version of WorldWind is available online. An Android version is also available.
Satellite images are images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell images by licensing them to governments and businesses such as Apple Maps and Google Maps.
TerraServer was a commercial website specializing in aerial and satellite imagery which was originally launched in 1997. It is owned and operated by TerraServer.com, Inc. in Raleigh, North Carolina. The company was previously named Aerial Images until May 2002 when the assets of Aerial Images were sold and the company renamed itself TerraServer.com, Inc.
Google Earth is a computer program that renders a 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposing satellite images, aerial photography, and GIS data onto a 3D globe, allowing users to see cities and landscapes from various angles. Users can explore the globe by entering addresses and coordinates, or by using a keyboard or mouse. The program can also be downloaded on a smartphone or tablet, using a touch screen or stylus to navigate. Users may use the program to add their own data using Keyhole Markup Language and upload them through various sources, such as forums or blogs. Google Earth is able to show various kinds of images overlaid on the surface of the earth and is also a Web Map Service client. In 2019, Google has revealed that Google Earth now covers more than 97 percent of the world, and has captured 10 million miles of Street View imagery.
A virtual globe is a three-dimensional (3D) software model or representation of Earth or another world. A virtual globe provides the user with the ability to freely move around in the virtual environment by changing the viewing angle and position. Compared to a conventional globe, virtual globes have the additional capability of representing many different views of the surface of Earth. These views may be of geographical features, man-made features such as roads and buildings, or abstract representations of demographic quantities such as population.
Earth Satellite Corporation (EarthSat), an American company, was a pioneer in the commercial use of Earth observation satellites. Founded in 1969, EarthSat was first headquartered in Washington, D.C., and later moved its offices to Bethesda, Maryland, and finally to Rockville, Maryland, in the late 1980s. In 2001, EarthSat was acquired by MacDonald, Dettwiler and Associates Ltd. (MDA) of Vancouver, British Columbia. In August 2005, EarthSat was incorporated as MDA Federal Inc., the U.S. operation of MDA Geospatial Services.
GeoEye Inc. was an American commercial satellite imagery company based in Herndon, Virginia. GeoEye was merged into the DigitalGlobe corporation on January 29, 2013.
Space Imaging Middle East LLC (SIME) is a regional affiliate of DigitalGlobe, the largest commercial remote sensing company in the world.
ImageAmerica is an aerial photography company that was acquired by Google in July 2007. The company specialized in creating aerial photos with "accuracy, quick delivery and low cost". It previously sold its services primarily to city, county, state, and federal governments and to corporate customers. ImageAmerica also made money by selling low-cost imagery to county appraisers and assessors. The company's clients include the Texas Department of Transportation, the U.S. Geological Survey, and the Lucas County office that covers Toledo, Ohio. For satellite imaging, the company charges US$99 per 1 square mile (2.6 km2), compared to other companies which could charge from $500 to $700 and for a lower quality than what ImageAmerica offers. It also developed its own DDP-2 camera system. The system is housed in an aircraft. It has the ability to capture details as small as 6 inches (150 mm) to 12 inches (300 mm). ImageAmerica's patented processing system has the ability to produce orthorectified imagery corrected for perspective distortions. The company's technology also uses sensors which are based on a unique design from Sarnoff Research Labs in Princeton, New Jersey.
Nearmap is an aerial technology company headquartered in Australia that provides frequently-updated, high-resolution aerial imagery and location intelligence on up to 95% of Australia's population, 80% of the United States population, 75% of the New Zealand population, and 66% of Canada's population. It was a publicly traded company on the Australian Securities Exchange until being taken private by Thoma Bravo in 2022.
Maxar Technologies Inc. is a space technology company headquartered in Westminster, Colorado, United States, specializing in manufacturing communication, Earth observation, radar, and on-orbit servicing satellites, satellite products, and related services. DigitalGlobe and MDA Holdings Company merged to become Maxar Technologies on October 5, 2017. Maxar Technologies is the parent holding company of Space Systems Loral, headquartered in Palo Alto, California, US; DigitalGlobe, headquartered in Westminster, Colorado, US; and Radiant Solutions, headquartered in Herndon, Virginia, US. Maxar Technologies is dual-listed on the Toronto Stock Exchange and New York Stock Exchange as MAXR.
Comtal Corporation was an American electronics company that was one of the first to specialize in digital image processing. It was founded in the early 1970s and was acquired by 3M in 1980. Users of Comtal image processors included NASA, the military, computer-aided designers, X-ray technicians, and engineers in the field of signal processing.
References
- ↑ "GlobeXplorer, Inc. Unveils World's Largest Online Earth Imagery Archive". Space Daily. April 4, 2000.
- ↑ "GlobeXplorer Acquires AirPhotoUSA". GIM International. September 12, 2005.
- ↑ "Stewart REI Group sells GlobeXplorer to DigitalGlobe" (Press release). Business Wire. January 8, 2007.
- ↑ YAMANOUCHI, KELLY (January 8, 2007). "DigitalGlobe buys GlobeXplorer". The Denver Post .