simulator makes local news

Buck Murdock wrote:
In article ,
Mxsmanic wrote:

Oh, come on. Live a little. Take a chance.

I don't engage in thrill-seeking behavior.

And yet you're running Windows. Curious.

and posting here. very curious.

Jay Honeck wrote:
I see three projectors. Unless they have very special lenses indeed,
I don't see how they can project clear images onto curved screens.


Setting up the over-lap between the screens so that it doesn't look
weird must be a tricky affair, indeed.

(Gears turning...where can I mount a curved screen? Whey can I even
*buy* a curved screen? :-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

http://www.e-planetarium.com/

You can run movies in them too.

Margy

Jay Honeck wrote:

Setting up the over-lap between the screens so that it doesn't look
weird must be a tricky affair, indeed.

Sorry abbout piggy-backing this on Margy - Jay's post was gone.

You could see where the projector's image ends on the screen and mask and
paint a thin black line on the screen. That would make overlap a non issue,
and be a minimal distraction. That would be the easy way out.

(Gears turning...where can I mount a curved screen? Whey can I even
*buy* a curved screen? :-)

Get some bulk screen material, and sew a flap on the bottom and the top of
the material. Get some thin wall electrical conduit, and bend the
appropriate radius in the tube, with a top and bottom matching tube. You
would want to weld the joints, instead of using a connector. If you weld it
yourself, be sure to not breath the fumes, because the galvanized pipe
welding fumes will give you a very nasty headache, just for starts.

To mount it, make brackets to screw to the tubes, and fasten them on after
the screen has been streached on, so the screen will se the same tension
everywhere.

To make it somewhat portable, use some spreaders from the top to bottom
tube, mounted the same way, but mounted so they will be back away from the
screen. A mounting from the bottom to the floor could have some casters, so
you could roll it out of the way.

I'm not sure, but I think for the best results, a special lens would need to
be used, or a program to get the right aspect ration projected onto the
screen. Even then, I'm not so sure that it would be projected in focus
without a special lens, since the distance from the lens to a flat screen is
different (longer) at the sides of the picture as compared to the center of
the picture. With the curved screen, it would be the same distance on the
edges and the center.
--
Jim in NC

On Thu, 08 Feb 2007 20:41:38 -0500, Margy Natalie
wrote:

Jay Honeck wrote:
I see three projectors. Unless they have very special lenses indeed,
I don't see how they can project clear images onto curved screens.


Setting up the over-lap between the screens so that it doesn't look
weird must be a tricky affair, indeed.

(Gears turning...where can I mount a curved screen? Whey can I even
*buy* a curved screen? :-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

http://www.e-planetarium.com/

You can run movies in them too.

They are called planetariums:-))
There they build the curved surface and then spraypaint the reflective
surface on it.


Margy
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Even then, I'm not so sure that it would be projected in focus without a special lens, since the distance from the lens to a flat screen is different (longer) at the sides of the picture as compared to the center of the picture. With the curved screen, it would be the same distance on the edges and the center.

I'll bet it would be more in focus. I don't think lenses are designed
to take the straightness of a screen into account, and we just put up
with blurry edges and a sharper donut.

Jose
--
Humans are pack animals. Above all things, they have a deep need to
follow something, be it a leader, a creed, or a mob. Whosoever fully
understands this holds the world in his hands.
for Email, make the obvious change in the address.

"Jose" wrote in message
. net...
Even then, I'm not so sure that it would be projected in focus without a
special lens, since the distance from the lens to a flat screen is
different (longer) at the sides of the picture as compared to the center
of the picture. With the curved screen, it would be the same distance on
the edges and the center.

I'll bet it would be more in focus. I don't think lenses are designed to
take the straightness of a screen into account, and we just put up with
blurry edges and a sharper donut.

Jose
--
Humans are pack animals. Above all things, they have a deep need to
follow something, be it a leader, a creed, or a mob. Whosoever fully
understands this holds the world in his hands.
for Email, make the obvious change in the address.

Jose is correct. In a former life I was a projectionist. Lenses cannot
focus clearly on a flat screen, the best we could do was to settle for a
doughnut of focus that centered on the screen. Near the edges, and dead
center things were a little fuzzy. When Cinemascope came out, the wide
format required more screen. In the "Century" series theaters, we hung 3/4
inch strips of screen material vertically between the curved overhead risers
and a curved mount on the stage. Start with the center strip, then hang two
more, one to each side of the center one, and a 1/16 of an inch closer to
the lens, and angled in toward the lens maybe 1 degree. Each pair of strips
is mounted outside the growing center group, and angled carefully directly
toward the lens. Eventually you have a very wide screen, in which each strip
was positioned exactly the same distance from the lens, and pointing right
at it. The strips had to be stretched tightly, to avoid flutter in the air
conditioning. In a 20 foot high screen there was some vertical spreading
also, but we didn't have a good way of dealing with that.

Al G

On Dec 30 2006, 8:29 am, "Jay Honeck" wrote:
I see three projectors. Unless they have very special lenses indeed,
I don't see how they can project clear images onto curved screens.

Setting up the over-lap between the screens so that it doesn't look
weird must be a tricky affair, indeed.

(Gears turning...where can I mount a curved screen? Whey can I even
*buy* a curved screen? :-)


Jay -
see http://www.panoramtech.com/resource/spie1.html about complex
projection surfaces and multiple projectors - the theory behind it

also: http://www.vistasystems.net/ for boxes that do it.....


Randy

Jose writes:

I'll bet it would be more in focus. I don't think lenses are designed
to take the straightness of a screen into account, and we just put up
with blurry edges and a sharper donut.

It would be blurry. In order to project an image sharply onto all points of a
curved screen, you need a special lens, or a special projection source (if the
projected image is also curved in the right way, it will be projected onto a
curved screen correctly, but that would be very unusual--nobody is created
curved primary image sources for projection).

In large simulators multiple lensing systems _in front of the screens_ are
often used to produce collimated projections that appear to reside at
infinity, which is the most realistic way to present the visuals (anything
more than 20 metres or so away is pretty much at infinity for human vision).

--
Transpose mxsmanic and gmail to reach me by e-mail.

Al G writes:

Lenses cannot focus clearly on a flat screen ...

They can if they are designed correctly, but it has only recently become
possible to do that. Usually the departure from field flatness in good lenses
is small, even for older lenses.

--
Transpose mxsmanic and gmail to reach me by e-mail.