Editing Gnomonic projection (section)

==Use==
[[File:Admiralty Chart No 132 Gnomonic Chart of Indian and Southern Oceans, Published 1914.jpg|thumb|Admiralty Gnomonic Chart of the Indian and Southern Oceans, for use in plotting great circle tracks]]
Gnomonic projections are used in [[seismic]] work because seismic waves tend to travel along great circles. They are also used by [[navy|navies]] in plotting [[direction finding]] bearings, since [[radio]] signals travel along great circles. [[Meteor]]s also travel along great circles, with the Gnomonic [[Atlas Brno 2000.0]] being the [[International Meteor Organization|IMO]]'s recommended set of star charts for visual meteor observations. Aircraft and ship navigators use the projection to find the shortest route between start and destination. The track is first drawn on the gnomonic chart, then transferred to a Mercator chart for navigation.

The gnomonic projection is used extensively in [[photography]], where it is called ''[[Rectilinear lens|rectilinear]] projection'', as it naturally arises from the [[pinhole camera model]] where the screen is a plane.<ref>{{cite book | url=https://books.google.com/books?id=GlOzDQAAQBAJ&pg=PA669 | title=Handbook of Digital Image Synthesis: Scientific Foundations of Rendering | isbn=978-1-315-39521-0 | last1=Pegoraro | first1=Vincent | date=12 December 2016 | publisher=CRC Press }}</ref> Because they are equivalent, the same viewer used for photographic panoramas can be used to render gnomonic maps {{PanoLink|Equilateral_with_tissot.jpg}}.

The gnomonic projection is used in astronomy where the tangent point is centered on the object of interest.  The sphere being projected in this case is the celestial sphere, ''R''&nbsp;=&nbsp;1,  and not the surface of the Earth.

In astronomy, gnomic projection star charts of the [[celestial sphere]] can be used by observers to accurately plot the straight line path of a [[meteor]] trail.<ref name=Taibi_2016>{{citation | postscript=.
 | title=Charles Olivier and the Rise of Meteor Science
 | first=Richard | last=Taibi | date=November 25, 2016
 | page=67 | isbn=9783319445182
 | publisher=Springer International Publishing
 | url=https://books.google.com/books?id=nVyXDQAAQBAJ&pg=PA67 }}</ref>

{{comparison_azimuthal_projections.svg}}