What Are the Differences Between 3D Theater Versions?

[Drakkith]

Why are there two versions of 3d in the theaters? What's the difference between them?

 

[GregJ]

IMAX uses linear passive polarized glasses, which makes things "pop out" more. RealD uses circular polarized plastic instead, which gives you actual "depth".

RealD is considered the better of the two because you can move your head around without losing that 3D effect (plus i prefer the RealD glasses, they are usually lighter).

Also, the trouble with the IMAX is that they usually require special screens to show 3D (which also happen to be quite expensive) while RealD can be projected on to regular screens.

 

[Danger]

I used to think that IMax was the cat's ***, but now that 3D is available in regular theatres I won't likely go back to one. The glasses are so unnoticeable that I almost scared myself after my 3rd time watching "The Avengers". I hit the can, and glanced up at the mirror while washing my hands. I still had the glasses on, without realizing it. (That, incidentally, was over my regular eyeglasses.)
What I noticed about IMax was that I had to keep sweeping my gaze horizontally and vertically in an attempt to catch the full scene. That problem is eliminated when watching RealD on a normal-size screen.

 

[Mech_Engineer]

GregJ is wrong on a couple of counts:

IMAX uses linear passive polarized glasses, which makes things "pop out" more. RealD uses circular polarized plastic instead, which gives you actual "depth".

Neither of these simplistic views of the technology's stereoscopic polarization are accurate. Either technique is able to provide equal 3-D effect. "Pop out more" and "actual depth" are more dependent on how the movie was filmed, not the projection technique.

As a general rule, IMAX 3D is filmed using a pair of cameras in stereo at a distance of 2.5" (the same as the average human interocular distance). This provides a continuous 3-D image, like for example Avatar or a range of the IMAX 3D documentaries. A pair of cameras are used for imaging, and a pair of projectors are needed to project the film.
http://en.wikipedia.org/wiki/IMAX#IMAX_3D

RealD 3D is not too far different from IMAX save for a few points:
1) it uses a single double-speed projector with an LCD shutter which polarizes each frame (light starvation can be an issue compared to IMAX)
2) live action films are usually post-processed into 3-D (for example The Avengers, Titanic) which makes them more of a "layered" 3D instead of continuous. Digital animated movies are continuous 3D however.
http://en.wikipedia.org/wiki/RealD_Cinema

RealD is considered the better of the two because you can move your head around without losing that 3D effect (plus i prefer the RealD glasses, they are usually lighter).

This is true as far as I know, IMAX uses linear polarization which requires your glasses stay parallel to the screen (to avoid dimming) where as RealD 3D uses circular polarization allowing you to tip your head slightly (although too tilt much will cause parallax error so it's a moot point in my opinion). I haven't found either technology to be a problem personally.

Also, the trouble with the IMAX is that they usually require special screens to show 3D (which also happen to be quite expensive) while RealD can be projected on to regular screens.

False, both require silvered screens to maintain the polarization of the light after reflection. A standard white screen destroys the polarization and cannot be used with either technology. Film made a big difference also with IMAX having the larger format, but things being all-digital today the biggest difference is aspect ratio, IMAX being 1.44:1 (and usually on a much larger screen) where as RealD is typically the wider cinematic 2.39:1; HD television is 1.78:1 by the way so neither is a "perfect" fit.

http://en.wikipedia.org/wiki/Aspect_ratio_(image )

 

[GregJ]

You could have been just a tiny bit kinder in your reply ;)

Anyway, I must have missed out when reading that both screens are silvered. My bad.

 

[ThomasT]

Thanks for the info. We have tickets to see Prometheus at the local IMAX theater in 3D on Tuesday. I'll post here about that experience.

 

[Danger]

You could have been just a tiny bit kinder in your reply ;)

That wasn't an attack, although it might seem so. You did bring it upon yourself, however, by presenting an opinion as fact. Your opinion was wrong, so you were caught in a lie. Since this is an educational site, such is unacceptable. I'm rarely correct, but I always make sure to point out that I'm not sure of the real answer (even if I am sure). If you present your thoughts in that manner, you will be okay.

 

[Drakkith]

That wasn't an attack, although it might seem so. You did bring it upon yourself, however, by presenting an opinion as fact. Your opinion was wrong, so you were caught in a lie. Since this is an educational site, such is unacceptable. I'm rarely correct, but I always make sure to point out that I'm not sure of the real answer (even if I am sure). If you present your thoughts in that manner, you will be okay.

I don't think being incorrect means someone is lying.

 

[ThomasT]

You did bring it upon yourself, however, by presenting an opinion as fact.

I feel you meant no harshness, and sometimes I'm a bit abrupt in replying to a statement that I think I know is false. But it's also good to keep in mind, imo, that any and all assertions stated in these forums, no matter what evidence and/or documentation is cited, are, de facto, the opinions of those making the assertions. That is, unless someone explicitly states that their assertion is an expression of fact (not interpretation) of first hand experience, then it should be taken as a statement of belief/faith/interpretation, and therefore an opinion. So, I think that discussions can proceed without a bunch of superfluous reiterations of in my opionion and such. That is, this stating an opinion as a fact objection is silly, ie., a basis for unnecessary contention and argumentation. It would make some sense if we all didn't have the same resource (the internet) for researching stuff. But we do, so it doesn't.

I mostly like, and learn from, your posts Danger. So don't take my reply as any sort of challenge or whatever. Maybe I'm just venting. Though I do stand by what I said -- until refuted, of course.

I don't think being incorrect means someone is lying.

Indeed.

 

[GregJ]

Sorry for taking the thread far of it's topic.

Danger I was not lying. I actually found a website that mentioned all the information I replied with (which at the time I had believed to be correct). Obviously it appears that it is not a reliable source of information now :)
However, in light of your reply, I think that I shall be a little more careful in the future (and perhaps check with more reliable sources) before posting. Actually, I will also make sure to mention when a subject comes from knowledge or from external sources too (so that I do not come off looking quite so silly).

And to keep this a little on topic; I am really looking forward to Prometheus. You must let me know if it is worth going to see ThomasT (especially in IMAX 3D, as I now may have a choice between the two).

 

[Danger]

Greg, people have undoubtedly noticed that sometimes I don't realize how much customs vary geographically. Where I live, the term "caught in a lie" simply means "incorrect". It has nothing to do with intentional dishonesty. I apologize for using that particular turn of phrase.
Thanks to Drakkith and Thomas for bringing it to my attention.

 

[GregJ]

It's all good Danger. No need to apologise for anything, as I was the one whom made the mistake. I'll live and learn

 

[ThomasT]

I was going to delete my post #9 because I think I went a bit overboard with it, and there's probably some errors in it. But no need to dwell on that. Instead I'll just apologize to Danger, the members of the Academy, ... and everybody.

 

[Danger]

 

[ThomasT]

And to keep this a little on topic; I am really looking forward to Prometheus. You must let me know if it is worth going to see ThomasT (especially in IMAX 3D, as I now may have a choice between the two).

Ok Greg. My ticket says IMAX Prometheus 3D, 4:25 PM, 06/12/2012. Sometime later that evening I'll post my impressions. Wowee zowee, I can't wait!

 

[Mech_Engineer]

I wasn't attacking anyone, I simply wanted to get better technical information out there about the two technologies.

On another note I watched Prometheus in RealD 3D this weekend, it was good stuff!