Editing Photogrammetry (section)

=== Stereophotogrammetry ===
{{redirect-distinguish|Stereophotogrammetry|Roentgen stereophotogrammetry}}
{{main cat|Stereophotogrammetry}}
{{further|3D reconstruction from multiple images}}
{{see also|Computer stereo vision}}
<!-- [[WP:NFCC]] violation: [[File:Rapid3dmapping.jpg|thumb|300px|The stereophotogrammetry technology [[Rapid 3D Mapping]] applied on the Royal Castle of Sweden.]] -->

A special case, called '''stereophotogrammetry''', involves estimating the three-dimensional [[Coordinate system|coordinates]] of points on an object employing measurements made in two or more photographic images taken from different positions (see [[stereoscopy]]). Common points are identified on each image. A line of sight (or ray) can be constructed from the camera location to the point on the object.  It is the intersection of these rays ([[triangulation (computer vision)|triangulation]]) that determines the three-dimensional location of the point. More sophisticated [[algorithm]]s can exploit other information about the scene that is known ''[[A priori and a posteriori|a priori]]'', for example [[Symmetry|symmetries]], in some cases allowing reconstructions of 3D coordinates from only one camera position. Stereophotogrammetry is emerging as a robust non-contacting measurement technique to determine dynamic characteristics and mode shapes of non-rotating<ref>{{cite journal|title=Accuracy analysis of measuring close-range image points using manual and stereo modes|first=Jūratė|last=Sužiedelytė-Visockienė|date=1 March 2013|journal=Geodesy and Cartography|volume=39|issue=1|pages=18–22|doi=10.3846/20296991.2013.786881|doi-access=free|bibcode=2013GeCar..39...18S }}</ref><ref name="spie-turbine">{{cite conference|url=http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1315174|title=Dynamic characteristics of a wind turbine blade using 3D digital image correlation|last1=Baqersad|first1=Javad|last2=Carr|first2=Jennifer|last3=Lundstrom|first3=Troy|date=April 26, 2012|conference=[[Proceedings of SPIE]]|volume=8348|display-authors=2}}</ref> and rotating structures.<ref>{{cite book|title=Topics in Modal Analysis II, Volume 6|url=https://archive.org/details/topicsmodalanaly2012rhee|url-access=limited|first1=Troy|last1=Lundstrom|first2=Javad|last2=Baqersad|first3=Christopher|last3=Niezrecki|first4=Peter|last4=Avitabile|date=1 January 2012|publisher=Springer, New York, NY|pages=[https://archive.org/details/topicsmodalanaly2012rhee/page/n267 269]–275|doi=10.1007/978-1-4614-2419-2_26|chapter = Using High-Speed Stereophotogrammetry Techniques to Extract Shape Information from Wind Turbine/Rotor Operating Data|series = Conference Proceedings of the Society for Experimental Mechanics Series|isbn = 978-1-4614-2418-5}}</ref><ref>{{cite book|title=Special Topics in Structural Dynamics, Volume 6|url=https://archive.org/details/specialtopicsstr2013koiz|url-access=limited|first1=Troy|last1=Lundstrom|first2=Javad|last2=Baqersad|first3=Christopher|last3=Niezrecki|date=1 January 2013|publisher=Springer, New York, NY|pages=[https://archive.org/details/specialtopicsstr2013koiz/page/n388 401]–410|doi=10.1007/978-1-4614-6546-1_44|chapter = Using High-Speed Stereophotogrammetry to Collect Operating Data on a Robinson R44 Helicopter|series = Conference Proceedings of the Society for Experimental Mechanics Series|isbn = 978-1-4614-6545-4}}</ref> The collection of images for the purpose of creating photogrammetric models can be called more properly, polyoscopy, after Pierre Seguin <ref>Robert-Houdin, Jean-Eugene (1885) _[Magie et Physique Amusante](https://archive.org/details/magieetphysique00hougoog/page/n167/mode/2up "iarchive:magieetphysique00hougoog/page/n167/mode/2up")._ Paris: Calmann Levy p. 112</ref>