Hybrid front projector/overhead dome feasibility? - AVS Forum
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post #1 of 5 Old 06-15-2013, 07:16 PM - Thread Starter
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If my user name gives you a clue... i'm in the very early planning stages of an ultimate home theater/media room. One thing on my wishlist that probably is on almost nobody else's is support for dome type projection - some say there is no real content for this but there is - a home planetarium with star projector! As well as experimental media I hope to be playing around with, i'm actually wanting to create dome-projection content that would be commercially used elsewhere. So it's like a home mastering room of sorts like a home studio... but since the likelihood of success in that field is highly variable it's at least 50% for fun, home astronomy, and similar.

But i'm seeking opinions on whether it is possible to combine both of these in the same room. Whether there is a way to have both a 'normal' home theater type layout, as well as dome projection ability (even if it's longer off in the future before the dome projection ability is used) - examples of what i'm worried about are acoustics. In general domes are terrible for acoustics, yet i'm not sure whether I could just put acoustic absorbing mats behind screening for the dome, or have some kind of 'sliding ceiling' of acoustically absorbent material that effectively blocks off the dome when it's not being used as a projection surface. Or perhaps the room is actually a cube, and the 'dome' is just an acoustically transparent surface...



If it matters (and it probably does, concerning room modes and such) i'm wanting to have a rather extreme SPL and infrasonic supporting system - although that would primarily be used for normal front projection modes and not dome content it may affect the feasibility of blocking off sound with sliding ceiling tile if i'm creating 125-130db 8hz bass or something insane. Anything that gets too heavy, or too nuts/beyond home fabricator ability probably wont work. This is a system on a budget - not an ultra low budget, but there are limits. Ie - at the point when having two separate rooms costs less than one do everything room is an example. And i'm using cheap construction/planning to build the one or two rooms inside a barn.

In short, if I have to keep dome projection totally separate from normal home theater, I need to know at the outset to design them up separately.
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post #2 of 5 Old 06-15-2013, 07:42 PM
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There are dome planetariums that show movies, If I were you I'd visit a few for ideas. If they can do it to your satisfaction then it is just a matter of scaling it down for residential use, Good luck on your journey.

http://lasm.org/planetarium/about.shtml

Baton Rouge's mesmerizing star attraction—The Irene W. Pennington Planetarium— houses a 60-foot domed theater that is one of the most sophisticated multimedia presentation venues in the country. The theater presents digital movies, sky shows, and visual music shows using the most advanced visual and sound technology available. A 4K fulldome digital video projection system puts you in the center of the action, enveloped by a 5.1, 15,000-watt digital Surround Sound system.
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post #3 of 5 Old 06-15-2013, 09:39 PM
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Don't know if it ever showed up in a product with the feature(s) exposed, but the Silicon Optix guys (now part of IDT) had a dome projection running with the HQV chip doing the processing/correction. That was six years ago, IIRC. I assume if the planetariums are doing digital projection for films now they're using a commercial product to correct for the dome. Probably not cheap, but it would put you on the right track, so that you wouldn't be limited to pre-made content already distorted for dome projection...

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post #4 of 5 Old 06-22-2013, 05:40 PM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post

There are dome planetariums that show movies, If I were you I'd visit a few for ideas. If they can do it to your satisfaction then it is just a matter of scaling it down for residential use, Good luck on your journey.

http://lasm.org/planetarium/about.shtml

Baton Rouge's mesmerizing star attraction—The Irene W. Pennington Planetarium— houses a 60-foot domed theater that is one of the most sophisticated multimedia presentation venues in the country. The theater presents digital movies, sky shows, and visual music shows using the most advanced visual and sound technology available. A 4K fulldome digital video projection system puts you in the center of the action, enveloped by a 5.1, 15,000-watt digital Surround Sound system.

That's the first i'm aware of offhand, i'm in the northern midwest, any suggestions of something a little closer in range like in Chicago or Minneapolis? Or is there some handy dandy list of hybrid planetarium-theaters? Else it's going to take awhile before i'm traveling far enough to see such a thing.

Thats assuming we mean normal movies anyways instead of special fulldome presentations. My thing is i'm not sure whether i'd want to show movies on the dome, or on a separate screen where it's lay back in the recliner almost all the way to watch overhead dome presentation, or look forward for the normal presentation. I'm kind of inclined to a separate screen because being reclined for all movies may be wierd or unusual, the normal day to day content i'd just expect being in front. The dome would be like the special event less commonly used setup. The dome would also work for Cinemascope type presentations which wanted a curved instead of a flat screen. (and the normal theater would be a flat screen)

Quote:
Originally Posted by jautor View Post

Don't know if it ever showed up in a product with the feature(s) exposed, but the Silicon Optix guys (now part of IDT) had a dome projection running with the HQV chip doing the processing/correction. That was six years ago, IIRC. I assume if the planetariums are doing digital projection for films now they're using a commercial product to correct for the dome. Probably not cheap, but it would put you on the right track, so that you wouldn't be limited to pre-made content already distorted for dome projection...

Is there any more information than that? Searching for that I didn't see anything related... though it's more for curiosity.

Yes there are commercial "geometry correction" software, and some free or cheap http://www.domerama.com/software/dome-projection-software/ - getting the projection is not so much the concern (this project is at least two years off, i'm hoping to nudge certain corners for a more universal geometry correction solution by then) i'm just trying to sort out the room design including acoustics issues. One reason for considering separate 'dome projection' and front home theater, is as already mentioned, normally ugly sound in domes - they tend to reflect everything to the center really bad. Though that's more with hard surfaces.

There's an astronomy program that already does geometry correction in software, intended for use with a single DLP projector and like a metal reflecting bowl of sorts. It's not full dome, but covers most of it, and allows digital star projector shows even though i'll literally be watching secondhand markets to find someones old Spitz or similar physical star projector in the future. (this is a bit of a passion of mine and there would be educational purposes for this as well/i'm hoping to let local high schools and such do field trips once I get it in whenever they want to, etc.) They turn up so rarely that it might be years more to find one though. So it will be digital star projection first.

But before it's even that I need the room designed. : P Still open for suggestions/ideas on whether a dual purpose "box theater" and overhead dome is worth trying to make the same room around or not.
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post #5 of 5 Old 06-22-2013, 05:47 PM
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I found that one by doing a google search on "movies at planetarium" or some such
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