Click to join small_planetarium
a 3 meter dome
Ici version française
Abstract: to manufacture a microplanétarium (dome between 1 and 3 meter), it is necessary to project on the aforementioned cupola, an image manufactured by a PC, the software Stellarium and projected with an ordinary videoprojector.
1° images of the realization: dome out of paperboard of 1,2 meters
Stellarium Software: To download urgently if you do not know. Moreover, it is free! a relatively recent and fast graphics board is necessary to use technology OpenGl http://www.stellarium.org/index.html
Videoprojector: in this test, 2 projectors gave satifaction: the model commercial Infocus x1a, and model DIY, standard retrotft (Allinbox philosophy)
Dome: mainly out of paperboard
3° comments and limits of the system
the placement of the public is carried out not as in a traditional planetarium, but rather as for a traditional diaporama, by paying attention not to be interposed on the way of the luminous rays an interesting property of the videoprojector allows the clear manufacture of an image on a dome (depth of field)
the size of the dome of projection is limited by several factors:
If one wants to use the entirety of the dome, the extrèmes left and right edge can be deformed (stars in the shape of features). It is easy to correct this problem by projecting a circle slightly smaller than the dome.
According to the slope of the dome and the presence of a close ceiling, a part of the image can be projected out of the dome; with a projector "house" using an overhead projector, it is easy to remove this nuisance using a mask out of paperboard which one poses on a part of TFT.
This first test is encouraging. it shows that it is possible for a club or a private individual to manufacture a small planetarium at a reasonable cost. the certainly limited resolution is partly compensated by the wide functionalities which proposes the Stellarium software. If you have already of a PC and a projector, the experiment is not very expensive and deserves to be tried.
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