An orthophoto, orthophotograph, orthoimage or orthoimagery is an aerial photograph or satellite imagery geometrically corrected ("orthorectified") such that the scale is uniform: the photo or image follows a given map projection. 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,[1]lens distortion, and camera tilt.
Orthographic views project at a right angle to the datum plane. Perspective views project from the surface onto the datum plane from a fixed location.Aerophotogrammetry, orthophoto from drone, Città Alta, Bergamo, Italy.This photo is properly projected on elevation model, yet on a single building scale, a small tilt is noticeable. This is an orthophoto, but not a true orthophoto (not all vertical features are reprojected).This photo is assembled from several overlapping photos from UAV, completely removing any residual tilt of the buildings. This is a true orthophoto.
Orthophotographs are commonly used in geographic information systems (GIS) 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.[2]
The orthorectification is not always perfect and has side effect especially for the geometry of high-rise constructions.
An orthophotomosaic is a raster image 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.[3]Google Earth 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.
Aerial orthorectified image of a mine for volumetric measurements in stock pile reporting.
^BBC Tomorrow's World: How maps are corrected and updated using aerial photography and optical machinery. 18 December 1970.
^American Congress on Surveying and Mapping, American Society for Photogrammetry and Remote Sensing (1994), Glossary of the Mapping Sciences, American Society of Civil Engineers, p. 370, ISBN9780784475706
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.
Fernandez, E.; Garfinkel, R.; Arbiol, R. (May–June 1998). "Mosaicking of Aerial Photographic Maps Via Seams Defined by Bottleneck Shortest Paths". Operations Research. 46 (3): 293–304. doi:10.1287/opre.46.3.293..
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.
National Digital Orthoimagery Program Subcommittee
October 27, 2023
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This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations February 2009 Learn how and when to remove this template message An orthophoto orthophotograph orthoimage or orthoimagery is an aerial photograph or satellite imagery geometrically corrected orthorectified such that the scale is uniform the photo or image follows a given map projection 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 1 lens distortion and camera tilt Orthographic views project at a right angle to the datum plane Perspective views project from the surface onto the datum plane from a fixed location Aerophotogrammetry orthophoto from drone Citta Alta Bergamo Italy This photo is properly projected on elevation model yet on a single building scale a small tilt is noticeable This is an orthophoto but not a true orthophoto not all vertical features are reprojected This photo is assembled from several overlapping photos from UAV completely removing any residual tilt of the buildings This is a true orthophoto Orthophotographs are commonly used in geographic information systems GIS 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 2 The orthorectification is not always perfect and has side effect especially for the geometry of high rise constructions Contents 1 Orthophotomap 2 See also 3 References 4 External linksOrthophotomap edit nbsp Orthophotomap of Rockport Texas The orthophotomap contains additional roads terrain elevation and bathymetry layers nbsp Orthophotomap of Oviedo city center Spain An orthophotomosaic is a raster image 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 3 Google Earth 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 nbsp Aerial orthorectified image of a mine for volumetric measurements in stock pile reporting See also editDigital Orthophoto Quadrangle DOQ and Digital Orthophoto Quarter Quadrangle DOQQ Leica Photogrammetry Suite Orthorectification Software GRASS GIS i ortho photo module Photogrammetry Photomapping TopoFlight Socet set Orthophoto Software U S Geological Survey Rational Polynomial CoefficientReferences edit Smith Gary S Digital orthophotography and GIS ESRI Conference http proceedings esri com library userconf proc95 to150 p124 html BBC Tomorrow s World How maps are corrected and updated using aerial photography and optical machinery 18 December 1970 American Congress on Surveying and Mapping American Society for Photogrammetry and Remote Sensing 1994 Glossary of the Mapping Sciences American Society of Civil Engineers p 370 ISBN 9780784475706 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 amp Sons Fernandez E Garfinkel R Arbiol R May June 1998 Mosaicking of Aerial Photographic Maps Via Seams Defined by Bottleneck Shortest Paths Operations Research 46 3 293 304 doi 10 1287 opre 46 3 293 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 amp 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 htmlExternal links editUnited States Geological Survey National Digital Orthophoto Programs NDOP Original Site via Wayback Machine National Digital Orthoimagery Program NDOP National Digital Orthoimagery Program Subcommittee Retrieved from https en wikipedia org w index php title Orthophoto amp oldid 1170973058, wikipedia, wiki, book, books, library,
