Half a croissant, on a plate, with a sign in front of it saying '50c'
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Full Spherical Planetarium

A planetarium that wraps over a full sphere (not a hemisphere) would be awesome.
  [vote for,

Once when I was daydreaming I though it would be cool if you could get a 360- degree planetarium as a room in your house. The idea would be to have a chair or such on a metal pole in the middle of sphere with a retractable gangplank. When turned on, it would create the sensation of floating in the middle of space, which I think would be calming and meditative (and hopefully not like the Total Perspective Vortex!).

I don't think this could be done with projection like traditional planetariums, since I want to sit where the projector would be. This could be done cheaply by wrapping the inside of the sphere with perforated sheets, but I think that would look like crap. Better still might be if you could curve high-definition displays then you could run images on the inside of the sphere theoretically (like floating outside the galaxy and looking at it). Alternatively, I suppose a good VR setup could handle this more cheaply, but I like the idea of not being able to wear goggles. And it would be nice if you could make it large enough that it could support multiple people (maybe with a clear floor).

harrisj, May 13 2005

Celestia http://www.shatters.net/celestia/
Virtual Galaxy, Open Source, downloadable for your computer (Mac, Linux and Windows) Very nice program, with lots of user generated add-ons. Not exactly a full spherical planetarium, but definitely 3D virtually tourable. [Soterios, May 13 2005]

My old QTVR work from 1999 http://tindale.dyn.nu/qtvr/
[Ian Tindale, May 13 2005]

The C6 6-Walled Cave at Iowa State
needs a 3 story building to house it, 24 4K projectors, full stereo, etc. Awesome, but not cheap. Someone needs to write a planetarium app. [cowtamer, Sep 01 2009]


       Strictly speaking, it doesn't have to be a sphere. If you look at the way a QTVR cubic panorama* works, it's (virtually) effectively six flat planes, with pre- distorted stitched images projected onto the flat planes, and the software in the QTVR view of QuickTime player 'undistorts' it on the fly as you rotate the panorama.
The same kind of thing could conceivably happen in real life - you sit in a cube, the six sides of which are projection screens, the relevant cube-face-worth of imagery projected from the other side of each plane. If done correctly, with the predistortion and stitching, and correction for the light drop-off towards the edges of the cube face projection surfaces, it should (I'm guessing) appear like you're inside a seamless spherical space. Probably.

       * The ones I did aren't cubic panos, they're cylindrical panos. Cubic panos weren't possible when I was doing them.
Ian Tindale, May 13 2005

       Thanks for the tip Ian!
harrisj, May 13 2005

       ...for a cheap version, you could paint the night sky on the walls and ceilings with luminous paint. I've seen that done. Not the carpet, though, that didn't work so well.
moomintroll, May 13 2005


       Another HHGTTG fan! Welcome!
DesertFox, May 17 2005

       "Since the human head at most has 180 degrees of periphrial vision..."   

       There's some pro basketball players who might disagree with you.   

       You could do this with 2 conventional planetarium projectors, each covering half of the sphere. You could arrange them to be either above and below your suspended seat or on either side. In the latter example each projector would display either the eastern or western skies and in the former, the northern and southern skies.   

       One other thing to point out is that planetarium screens are rarely a subsection of a perfect sphere. They are usually closer to a parabola and need to be as the seating is well below the bottom edge.   

       Finally...ever priced a planetarium projector? Hint: the good ones are made by Zeiss.
bristolz, May 17 2005


       I'l bet that, using a pair of even the far less costly Spitz projectors, along with 30' dome (or, in this case, sphere) construction would top $3 million, half going to the cost of the projectors. 50% more if you used Minolta projectors and god only knows how much more with Zeiss.   

       (By the way, UB, you have a magnificent Zeiss Spacemaster at the Brisbane Planetarium that's been customized to do all manner of extra things. It's one of Zeiss's double-ended or "dumbell" models and I bet it was millions)
bristolz, May 17 2005


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