P3D RE: IMAX polarized (was IMAX anaglyph)

[donaldparks@xxxxxxxxxx]

> Eddie Bowers wrote<
> Speaking of IMAX glasses. I went to see the IMAX T-Rex show not long ago and
> I loved the polarized glasses they handed out. I tried to ask the manager
> about buying a couple of pair from them, but he thought I was a crazy person
> :)
> He attempted to explain to me how 3D worked and that they would be useless
> to me. Trying to explain that I actually could use them made me look more
> insane I think.
>
> Anyone know how to get these?

     There's a new IMAX in Boise Idaho.  I went to see T-Rex and brought a pair of
regular stereo polarized clip-ons to try.  I discovered that the polarization used
for the IMAX projection is not the standard 45-45 degree orientation.  Their glasses
were horizontal-vertical orientation.  I couldn't use my clip-ons.  The supplied
polarized glasses worked very, very well.  I couldn't detect significant ghosting
even when the left and right image separations were several feet on the screen with a
light object against a black background.  These were objects sticking way out at
you.  I'd like to know how they make the polarization work this well.

    Perhaps their method for coating the screen is much better than the standard
Dalite silver lenticular.  An introduction given for the first few performances
stated that they sprayed the reflective coating onto the stretched screen cloth.
They switched on some lights behind the screen so the audience could see the support
structure behind the screen.  The screen must be porous because light could pass
through it from behind.  Does anyone know how they make their screens?

Dr. Donald Parks
Mechanical Engineering Dept.
Boise State University