![Aerial Orthophoto](https://upload.wikimedia.org/wikipedia/commons/9/96/Aerial_Orthophoto.png)
An orthophoto, orthophotograph, orthoimage or orthoimagery is an
aerial photograph
Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other airborne platforms. When taking motion pictures, it is also known as aerial videography.
Platforms for aerial photography include fixed-wing ai ...
or
satellite imagery
Satellite images (also Earth observation imagery, spaceborne photography, or simply satellite photo) are images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell ima ...
geometrically corrected ("orthorectified") such that the scale is uniform: the photo or image follows a given
map projection
In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longitud ...
. Unlike an uncorrected aerial photograph, an orthophoto can be used to measure true distances, because it is an accurate representation of the Earth's surface, having been adjusted for
topographic relief
Terrain or relief (also topographical relief) involves the vertical and horizontal dimensions of land surface. The term bathymetry is used to describe underwater relief, while hypsometry studies terrain relative to sea level. The Latin word ...
,
lens distortion, and
camera tilt
Tilting is a cinematography, cinematographic technique in which the camera stays in a fixed position but rotation, rotates up/down in a vertical direction, vertical plane (mathematics), plane. Tilting the camera results in a motion similar to ...
.
Orthophotographs are commonly used in
geographic information system
A geographic information system (GIS) is a type of database containing Geographic data and information, geographic data (that is, descriptions of phenomena for which location is relevant), combined with Geographic information system software, sof ...
s (
GIS
A geographic information system (GIS) is a type of database containing Geographic data and information, geographic data (that is, descriptions of phenomena for which location is relevant), combined with Geographic information system software, sof ...
) as a "map accurate" background image. An orthorectified image differs from "rubber sheeted" rectifications as the latter may accurately locate a number of points on each image but "stretch" the area between so scale may not be uniform across the image. A
digital elevation model (DEM) is required to create an accurate orthophoto as distortions in the image due to the varying distance between the camera/sensor and different points on the ground need to be corrected. An orthoimage and a "rubber sheeted" image can both be said to have been "georeferenced"; however, the overall accuracy of the rectification varies. Software can display the orthophoto and allow an operator to digitize or place linework, text annotations or geographic symbols (such as hospitals, schools, and fire stations). Some software can process the orthophoto and produce the linework automatically.
Production of orthophotos was historically achieved using mechanical devices.
Orthophotomap
![C 44 OVIEDO CENTRO](https://upload.wikimedia.org/wikipedia/commons/2/2b/C_44_OVIEDO_CENTRO.jpg)
An orthophotomosaic is a
raster image
upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for ...
made by merging orthophotos — aerial or satellite photographs which have been transformed to correct for
perspective so that they appear to have been taken from vertically above at an infinite distance.
Google Earth
Google Earth is a computer program that renders a 3D computer graphics, 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposition, superimposing satellite images, aerial photography, and geog ...
images are of this type.
The document (digital or paper) representing an orthophotomosaic with additional marginal information like a title, north arrow, scale bar and cartographical information is called an orthophotomap or image map. Often these maps show additional point, line or polygon layers (like a traditional map) on top of the orthophotomosaic. A similar document, mostly used for disaster relief, is called a
spatiomap
A spatiomap is a document similar to a map, but based on an orthophoto. Often, some annotations are added to the orthophoto. Similar to normal maps, can display a north arrow, a scale bar and cartographical information like the used projection. ...
.
See also
*
Aerial Photography
Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other airborne platforms. When taking motion pictures, it is also known as aerial videography.
Platforms for aerial photography include fixed-wing aircra ...
*
Digital Orthophoto Quadrangle (DOQ) and Digital Orthophoto Quarter Quadrangle (DOQQ)
*
Leica Photogrammetry Suite
IMAGINE Photogrammetry (formerly Leica Photogrammetry Suite – LPS) is a software application for performing photogrammetric operations on imagery and extracting information from imagery. IMAGINE Photogrammetry is significant because it is a le ...
Orthorectification Software
*
GRASS GIS
''Geographic Resources Analysis Support System'' (commonly termed ''GRASS GIS'') is a geographic information system (GIS) software suite used for geospatial data management and analysis, image processing, producing graphics and maps, spatial and ...
(i.ortho.photo module)
*
Photogrammetry
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima ...
*
Photomapping
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima ...
*
TopoFlight TopoFlight is a three-dimensional flight planning software for photogrammetric flights.
Originally conceived by a team of experts in the mapping industry, it has been in use since 2003. The program is used to facilitate the planning of flight line ...
*
Socet set Orthophoto Software
*
U.S. Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...
*
Rational Polynomial Coefficient
References
* Bolstad, P., (2005), GIS Fundamentals: A First Text on Geographic Information Systems, Eider Press, White Bear Lake, MN, 2nd ed.
* Demers, Michael N., (1997). Fundamentals of Geographic Information Systems, John Wiley & Sons.
* {{cite journal, authors=Fernandez, E., Garfinkel, R. & Roman Arbiol, title=Mosaicking of Aerial Photographic Maps Via Seams Defined by Bottleneck Shortest Paths, date=May–June 1998, journal=Operations Research, volume=46, number=3, pages=293–304, doi=10.1287/opre.46.3.293 , doi-access=free.
* Petrie, G., (1977), Transactions of the Institute of British Geographers: Orthophotomaps New Series, vol. 2, no.1, Contemporary Cartography., pg. 49-70
* Robinson, A.H., Morrison, J.L., Muehrcke, P.C., Kimerling, A.J., Stephen Guptill, (1995) Elements of Cartography: John Wiley & Sons Inc., Canada, 6th ed.
* United States Geological Survey, US Department of Interior, USGS Fact Sheet May 2001 http://erg.usgs.gov/isb/pubs/factsheets/fs05701.html
* Zimbabwe Uberty Alton the technician and the GIS director of 2022
External links
United States Geological SurveyNational Digital Orthophoto Programs (NDOP) - Original Site via Wayback MachineNational Digital Orthoimagery Program (NDOP)National Digital Orthoimagery Program Subcommittee
Cartography
Remote sensing
Photogrammetry