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Anyone ever projected onto a curved screen?

753 Views 14 Replies 12 Participants Last post by  Cain
Oddball question I know, but I need to put two projectors side by side and project them onto a big curved wall.

Think of the large control room style setups, thats what we are trying to achieve.


Anyone got any links on this type of thing??
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Im just guess here but I think if you have a curved wall everything will look all stretched up and down.. Im not sure but Im sure someone can answer it..


Chris
There is probably a lens you can buy that will project onto a curved call.
Is there a particular reason to do a curved screen? Are you stuck with the decision?


I've always found curved screens of any kind distort geometry too much. Even if geometry does "map" properly onto the screen, the screen being curved distorts the appearance of objects from any real distance, particulaly if the person is off-center. I would think that proper geometry would be important in a control room, but I guess I don't know all the considerations.
Most movie theaters have screens curved horizontally. I want to make a huge curved gaming screen, and I found the depth of focus on my Marantz would allow about eight inches of curve across fourteen feet and still be in the 'best' sharpness range. So it's no big deal if the curvature is slight. (That project is still in the works...)


In the olden days, you could get silver screens strongly curved in both axes, to focus a hot spot on the viewing area. If you looked past the curvature when converging the PJ, you could end up with good apparent geometry from a suprisingly wide area.


Digital projectors don't have the bow, pincushion, and so on adjusments to allow this, though. And don't expect to use some dual-monitor software to make a seamless image; it just won't work.


The only trick is to adjust the focus on a part of the screen that is the average distance from the PJ instead of the center. This would be halfway to the edges along the horizontal centerline on a constantly curving wall like a 'cinerama' screen.


-Cart

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dakyman,


you should look at Prismasonic screens, they have curved models available. Due to new forum rules I can't provide you with a link, but I'm sure you can find the company by using Google.


cheers,

Halcy


PS If they don't advertise it on their sites, ask them - I've seen it demoed and it works quite well.
You might find these posts interesting if you haven't seen them yet. This has been quite a bit of discussion about this on the Screen Forum.

http://www.avsforum.com/avs-vb/showt...hreadid=122431
http://www.avsforum.com/avs-vb/showt...hreadid=101363
Projecting on a curved wall requires the use of a CRT projector that has separate focusing adjustments for the center and the edges of the picture. Digital projectors should not be used with curved surfaces.


Lenny Eckian
Quote:
Originally posted by FlatusM
Most movie theaters have screens curved horizontally
How slight is this? Even when up close & practically under it, I don't notice any curvature on most of the screens I've looked at. I think I did notice a couple IMAX screens having a slight curve to it.
"use of a CRT projector that has separate focusing adjustments for the center and the edges of the picture. Digital projectors should not be used with curved surfaces."


How wrong can you be . If ever 2.35 aspect ratio anamorphic projection becomes popular, The compound curved screen will be the ideal screen.
http://www.xtremedtv.com/images/torus%20screening.jpg
I've seen Alan Gouger do a curved screen at his avscience theater and it looked super. Maybe he can speak on it, how about it Alan. slammie
I have a curved screen, using a Seleco HT300.


The Seleco has a very long throw distance which also equates to greater depth of field.


The middle is as sharp as the sides on my screen.


-- Cain
A digital projector has one simple focusing adjustment. If you focus for the center of the image and the sides curve inward they will not be as precisely focused as the center.
Im a fan of curved screens.


A crt works well with a curved screen because of the convergence adjustments available.


A digital projector needs to fire its image from center of lens. to avoid geometry distortion. None do this except for the seleco that I know of.
Also, as Don Stewart told me. The longer the digital projector's throw, the greater its depth of field.


-- Cain
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