Dome projection

[Thorvald]

So does anyone yet make and sell a dome (quarter sphere) in North America?

 

That Frex demo looked awesome, three projectors or even four to get the rear view would be amazing.

[Feed]

Some of my more odd-ball ideas as of late would be to buy a 12 foot diameter beech ball from ebay and cast a composite layup mold from it to be sanded down and refined to be seamless and uniform. I could make composite layup screens from it. I have degrees in manufacturing engineering and composites engineering (among other things) so it's not too difficult to make a composites mold for something like that. Just takes time, space and patience (and a heck of alot of sanding).

 

Without oddball ideas, we'd still be walking everywhere!! I was reading at the Desert Domes site (someone posted a link here) and immediately got all excited - but I'm just nowhere near that point, yet. I think combining a few of the ideas in this thread could lend some pretty spectacular results - sure, there's distortion issues to work out, seams to eliminate, etc., but the immersion factor might make the small imperfections seem to disappear if the overall effect were good.

[BHawthorne]

So does anyone yet make and sell a dome (quarter sphere) in North America?

 

That Frex demo looked awesome, three projectors or even four to get the rear view would be amazing.

 

The consumer market for this stuff is highly speculative at this point. Until recently I've been the only one really pushing entry level integration on the NTHUSIM side of things. There are now a few small players in the market though. Everything is highly DIY orientated though, which has to require significant experimentation and willingness to take the risks associated with the unknowns involved.

 

While I believe I have worked through the issues involved to make a good circular screen installation, dome fabrication is all just make it up as I go right now. Basically, what needs to be done is to look at the size and shape you want to replicate in other consumer markets and adapt it for projection. That requires really thinking outside the box. It means researching out materials like Plexiglas skylights to be painted with rear projection Goo Paint or things like satellite parabolic dishes, geodesic dome tents, or interior dome vault kits for building construction. Things that would never typically be targeted at our end use.

 

For circular projection, it's close enough to flat screen that materials and production methods can be similar. But for things like dome, you have to really think outside the box to find plausible answers.

 

At this point in time I think the best compromise between circular and dome projection is Paul Bourke's iSphere concept. If I was to fabricate something next, this design really appeals to me because of it's 120/360 FOV. Now only to figure out how something like the DCS engine could harness something like that. At the time iSphere was conceived the hardware and software required to pull it off didn't exist. Now it does in AMD 4x1L Eyefinity mode and Immersaview Sol7 for four projector. I just wish NTHUSIM Plus could do four projector. It's currently limited to three with no edge blending. Sol7 can do it all though. If I had a matched set of 4 projectors (preferably 1080p) I'd DIY build this concept in a heatbeat. I currently only have 720p and 1024x768 projectors in matched triple sets though.

 

http://local.wasp.uwa.edu.au/~pbourke/miscellaneous/domefisheye/isphere/

Edited February 12, 2011 by BHawthorne

[Thorvald]

Hmm that does look interesting.

 

Great another expensive item that has my attention lol.

 

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Does anyone make the curved screens yet? I assume they are simply white paper/cloth?

 

Use a couple of short throw projectors and voila.

 

Tim

[BHawthorne]

Hmm that does look interesting.

 

Great another expensive item that has my attention lol.

 

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Does anyone make the curved screens yet? I assume they are simply white paper/cloth?

 

Use a couple of short throw projectors and voila.

 

Tim

 

There are sources for circular projection screens, but they're ungodly expensive. The most effective route is DIY at the moment. There are different materials that can be used to achieve the same end. Depends if you want a fixed screen or portable. A fixed screen is much more cost effective to build, but has the disadvantage of once it's built it's there until torn down. Regular lumber and plywood is the best choice for that sort of build. Once built, sand, finish and paint the projection surface to your needs.

 

I've also used raw canvas tacked to trim, 4-ply pvc screen material in bulk from ebay and stretch screen material such as Rose Brand Tendo. My current preference is Rose Brand Tendo cloth. You need to be very mindful to not over-tension the cloth though as the geometry of the curve will bow the material forward with too much tension.

 

There are many ways to achieve a functional screen. It really depends upon your end use, the location it's used and if it's to be a permanent built.

Edited February 12, 2011 by BHawthorne

[BHawthorne]

For those of you looking for a cost effective DIY how-to, this might be interesting reading. It's planetarium based in focus but the same concepts apply:

 

http://www.worldwidetelescope.org/Docs/worldwidetelescopeplanetarium.html

[desqjockey]

Tha'ts exactly what I want, except with a smooth screen!