Projection
https://plus.maths.org/content/taxonomy/term/343
enPutting it in perspective
https://plus.maths.org/content/putting-it-perspective
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Mathematics is helping the blind move forward and us all to step inside the past. </div>
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<div class="pub_date">27/09/2002</div>
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Ever since the Renaissance, painters have used projective geometry - the mathematics of perspective - to render accurately our three-dimensional world on a two-dimensional canvas. Now researchers are using the same mathematics to recreate the three-dimensional reality of pedestrian crossings from photographs, in order to assist the blind.
<p>Obviously, it is difficult to cross roads when you are blind.<p><a href="https://plus.maths.org/content/putting-it-perspective" target="_blank">read more</a></p>https://plus.maths.org/content/putting-it-perspective#commentsmathematics and artProjectionThu, 26 Sep 2002 23:00:00 +0000plusadmin2741 at https://plus.maths.org/contentHow big is the Milky Way?
https://plus.maths.org/content/how-big-milky-way
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Toby O'Neil </div>
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A question which has been vexing astronomers for a long time is whether the forces of attraction between stars and galaxies will eventually result in the universe collapsing back into a single point, or whether it will expand forever with the distances between stars and galaxies growing ever larger. <b>Toby O'Neil</b> describes how the mathematical theory of dimension gives us a way of
approaching the question. </div>
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<div class="pub_date">May 2001</div>
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<h2>Introduction</h2>
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<div class="centreimage"><img src="/issue15/features/oneil/mw.gif" alt="[IMAGE: part of the Milky Way]" width="320" height="160" />
<p>A photograph of part of the Milky Way, courtesy of NASA</p><p><a href="https://plus.maths.org/content/how-big-milky-way" target="_blank">read more</a></p>https://plus.maths.org/content/how-big-milky-way#comments15boxdimensionCantor dustdimensionfractalProjectionscalingMon, 30 Apr 2001 23:00:00 +0000plusadmin2185 at https://plus.maths.org/contentAnalemmatic sundials: How to build one and why they work
https://plus.maths.org/content/analemmatic-sundials-how-build-one-and-why-they-work
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Chris Sangwin and Chris Budd </div>
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We've all seen a traditional sundial, where a triangular wedge is used to cast a shadow onto a marked-out dial - but did you know that there is another kind? In this article, <strong>Chris Sangwin</strong> and <strong>Chris Budd</strong> tell us about a different kind of sundial, the analemmatic design, where you can use your own shadow to tell the time. </div>
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<div class="pub_date">June 2000</div>
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<h2>Introduction</h2>
<p>Imagine that you have just got the latest in digital watches, with a stop watch, date, times from all over the world, and the ability to function at 4000 fathoms. There is just one small problem: the batteries have gone flat. However, if the sun is shining you don't need to use a watch at all, because the sun makes an excellent clock which (fortunately) doesn't need batteries that can run
down.<p><a href="https://plus.maths.org/content/analemmatic-sundials-how-build-one-and-why-they-work" target="_blank">read more</a></p>https://plus.maths.org/content/analemmatic-sundials-how-build-one-and-why-they-work#comments11angular distancedeclination of the sunellipseProjectionsundialtrigonometryWed, 31 May 2000 23:00:00 +0000plusadmin2168 at https://plus.maths.org/content