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Why isn't Real-D, well, real 3-D...?


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#1 Jim Carlile

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Posted 22 April 2009 - 11:36 PM

Anyone else bothered by the fact that Lenny Lipton's Real-D isn't really 3-D?

I was just reading an interview with Richerd Zanuck where he was talking about the fact that Tim Burton scrapped the real-D 3-D cameras in preference to shooting it in 2-D, because-- after all-- if they process it in Real-D it looks just the same, and the cameras are a hassle.

Apparently, most Real-D films are in reality shot as 2-D, and are then 'dimensionalized' via computer.

But hey-- that's not real 3-D! It's just an animation-like process that is essentially a cheat-- a special effect.

That's actually what 2-D Real-D is: a special effect !

Edited by Jim Carlile, 22 April 2009 - 11:37 PM.

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#2 K Borowski

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Posted 23 April 2009 - 10:01 AM

Well, even with a true 3-D setup, they exagerated the effect by spacing the camera lenses farther apart than 3-in. (~75mm), which would produce a 3-D effect the same as our eyes produce with their spacing.

By placing the cameras farther apart, like 6-in. (~150mm) you get the gimmicky ball-jumps-off-the-screen-and-is-coming-right -at-you effect that made people duck in the theatre while watching the movie.

Funny, I was just looking at this book last night, on the planet Mars, and they had a 3-D section in it.

They must have picked the worst possible set of pictures to fake 3-D, because they used orbital photos, and didn't exagerate perspective. With two lenses 3 inches apart from a distance of probably at least 60 nautical miles up (110km/70st.mi.), without exaggerated perspective, there's almost no 3D effect anyway, since the difference at that distance would be minimal.

This is why I don't think 3D will ever really catch on. It's been popular as a fad in the mid-1800s, early 1900s, 1950s, and now it's being pushed again, but I highly doubt it will catch on. It'll probably rear its ugly head again 50 years hence, but until they get rid of the silly glasses, yeah, it won't catch on.

What I really hope they'll figure out how to do is real 3D, full-color holography. Now that would be something.
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#3 Russell Scott

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Posted 23 April 2009 - 11:23 PM

Well, even with a true 3-D setup, they exagerated the effect by spacing the camera lenses farther apart than 3-in. (~75mm), which would produce a 3-D effect the same as our eyes produce with their spacing.

By placing the cameras farther apart, like 6-in. (~150mm) you get the gimmicky ball-jumps-off-the-screen-and-is-coming-right -at-you effect that made people duck in the theatre while watching the movie.


not to get off topic but that is wrong...

75mm is the average eye separation of a human, but it does not necessarily follow that you get the same depth effect. and for film work you generally want much less than 75mm
nor does camera separation define position-in-depth of objects...


carry on.... :ph34r:
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#4 K Borowski

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Posted 23 April 2009 - 11:26 PM

not to get off topic but that is wrong...

75mm is the average eye separation of a human, but it does not necessarily follow that you get the same depth effect. and for film work you generally want much less than 75mm
nor does camera separation define position-in-depth of objects...


carry on.... :ph34r:


OK, so instead of just telling me I am wrong, how far apart SHOULD they put two cameras?

And I definitely read that in a book on 3D photography published for the United States Navy, so I guess there are a lot of clueless sailors out there who are "misinformed" too :unsure:
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#5 Russell Scott

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Posted 23 April 2009 - 11:39 PM

OK, so instead of just telling me I am wrong, how far apart SHOULD they put two cameras?

And I definitely read that in a book on 3D photography published for the United States Navy, so I guess there are a lot of clueless sailors out there who are "misinformed" too :unsure:


depth is determined by the angular separation your eyes perceive. so if you capture 75mm separated stereo but double the projection area -without changing your distance from screen you effectively change your angular separation - i.e. you perceive more depth. or less depth when you halve the area by projecting it on a monitor.

the Navy probably use 75mm projections because they are trying to get human style space relations, i.e. identical to reality. That's a bad idea for movie making. I can't tell you what separation to use because that is determined by a whole bunch of factors. Factors like, how big its the screen being projected on, how far away will the audience be, what frame rate, how much is in front of/behind the screen, how fast are they moving, what came before it, whats your FOV...etcetc

As I said, filmmaking requires less than 75mm which is exactly why the cameras are a hassle (think about how wide a lens is)
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#6 K Borowski

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Posted 23 April 2009 - 11:56 PM

Since the human eye is the equivalent of less than 12mm, IIRC, wouldn't longer lenses need to be farther apart, not closer together?


One other little nitpick, I said 3 inches, not 75mm. So the figure I quoted is 76.2mm if you want to insist on using metrics :P
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#7 Russell Scott

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Posted 24 April 2009 - 12:49 AM

Since the human eye is the equivalent of less than 12mm, IIRC, wouldn't longer lenses need to be farther apart, not closer together?


One other little nitpick, I said 3 inches, not 75mm. So the figure I quoted is 76.2mm if you want to insist on using metrics :P


no, its the opposite. the wider the angle, the further apart you can have the cameras (to a point). this is because the eyes have two mechanisms working, one is toe-in the other is focus. this is really easy to explain in person but quite hard to explain on paper.
Imagine the depth expands as you reduce your FOV, thus your 'safe to film' zone needs to compress too (or reduce the separation )
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#8 Phil Rhodes

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Posted 24 April 2009 - 02:08 AM

I've never been entirely clear on this.

I am reliably informed that binocular vision does not really operate much beyond about thirty feet; human optical mechanics are not sufficiently sensitive to differentiate any more subtle degrees of convergence than that.

The screen is more than about thirty feet away.

Is it not therefore inevitable that the entire concept of theatrical 3D is based on having to force the effect to work when it really shouldn't, forcing the eyes to converge at a distance different to that which they're focussed to, and is this why it always, even when done very well (Beowulf at the Arclight Hollywood would be a "very well done" example) gives me a blinding headache?

I may be unusually sensitive to it; I'm one of the group of people who are deeply irritated by the chromatic stroboscopy of single-chip DLP displays and the Red (well, accuscene) viewfinder. I can also see the sorta-3D effect produced by the V3 moving-iris device. There seem to be two groups of people involved, one who see all these problems (and have a problem with this rather forced on-screen 3D) and those who don't.

P
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#9 Russell Scott

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Posted 24 April 2009 - 04:03 AM

I've never been entirely clear on this.

I am reliably informed that binocular vision does not really operate much beyond about thirty feet; human optical mechanics are not sufficiently sensitive to differentiate any more subtle degrees of convergence than that.

The screen is more than about thirty feet away.

Is it not therefore inevitable that the entire concept of theatrical 3D is based on having to force the effect to work when it really shouldn't, forcing the eyes to converge at a distance different to that which they're focussed to, and is this why it always, even when done very well (Beowulf at the Arclight Hollywood would be a "very well done" example) gives me a blinding headache?


go back to the angular separation I talked about. yes the screen is X feet/meters away but what is actually important is what distance the eye 'thinks' it is. you can fake any apparent depth you want, simply by adjusting the separation of the cameras.
Remember, the eyes are not picking up the depth of the room, they are picking up the depth of the image.

The focus issue is very much the problem with Stereographics, your focus is different to your convergence, unlike in reality.
There are tricks to fix this, but they are expensive, time consuming and difficult to achieve...

Having said that, "very well done' stereographics won't give you a headache but your margin for error is very small. A single bad shot can strain the eyes and compound throughout a movie. Its especially problematic with fast motion strobing. Even with good stereo, the strobing will hurt the eyes - this is why James Cameron wants 48fps, strobing is a fundamental problem. Motion blur helps but the amount you need to stop the problem can destroy the shot.
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#10 John Sprung

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Posted 24 April 2009 - 10:47 AM

Since the human eye is the equivalent of less than 12mm, IIRC, ....


Focal length for the human eye is typically near 25mm, much like our height is typically near 1.7 m. But just as we're not all the same height, we don't all have the same focal length. The eye focuses by changing its focal length rather than moving the lens back and forth. If you're at 25mm to focus at infinity, you'd "zoom" to maybe 23.8mm to read a book.





-- J.S.
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#11 Jim Carlile

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Posted 25 April 2009 - 12:31 AM

Yikes. I'll stick with super 8. In black and white. And on a real screen!
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#12 K Borowski

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Posted 25 April 2009 - 05:47 AM

Focal length for the human eye is typically near 25mm, much like our height is typically near 1.7 m.


I know 25mm is, like, 31/32", but what the hell is 1.7m?

I'm an American, but even the Brits and Canadians use feet and inches, pounds (and stone) for body measurements. . .
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#13 John Sprung

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Posted 26 April 2009 - 01:02 AM

I know 25mm is, like, 31/32", but what the hell is 1.7m?


5'-7". BTW, the inch is officially defined as exactly 25.4 mm



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#14 Karel Bata

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Posted 26 April 2009 - 04:26 AM

I suppose that's at sea level? We don't trust these new ways of doing things here in Olde Englande and stick with the 1814 legal definition: "three grains of sound ripe barley being taken out the middle of the ear, well dried, and laid end to end in a row". Hence our focus pullers always carry plenty of ripe barley in their gadgets boxes to double check any critical focussing. Nice also to get the rest of the crew involved in laying it out. Things can get a bit slow on a windy day.

;)
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