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3D Stereoscopic Production & Delivery
Discuss 3D (stereoscopic video) acquisition, post and delivery.


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Old February 2nd, 2010, 06:06 AM   #1
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Standardizing 3D

Hi
I'm a new filmmaker contemplating shooting a feature film on two REDs in India. But - since there are three major modes of doing 3D today - anaglyph, RealD and Dolby 3D, which one do I choose?

Will my choosing any one alter the way I will have to shoot the movie? I don't expect all effects to look equally good on all technologies. So it might be a good idea to confirm the delivery platform before commencing photography.

Also, for an indie filmmaker, what do I have to do in post production to ensure my output is in accordance with projection standards? Are there any white papers that spell it out? My last movie was mastered as an uncompressed TIFF sequence in 32 bit. Can I go the same route with 3D, but just have double the data?

I hope there was a guide for the indie filmmaker to embark on his 3D dream.
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Old February 2nd, 2010, 09:02 AM   #2
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the way you mentioned (anaglyph, RealD and Dolby 3D) are just for display.
It does not change the content. You shoot stereoscopic (two movies), you edit, and only then you eventually optimize the format for a particular display.
the real format are side by side, multiplexed, interleaved.
there are different flavor of each format depends where is left and right, can be top/bottom instead side by side, interleaved can be by row, column or frame.

only anaglyph is a bit appart since the information is totally different and you can hardly (but possibly) reconstruct the two movies from anaglyph.

RealD and Dolby 3D are just commercial hardware to display the picture, and most of them are using good old polarisation or shutter glass.
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Old February 3rd, 2010, 02:26 AM   #3
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No standard?

Thanks for the reply. So what should a filmmaker do to ensure his movie falls within certain standards? Like the interlocular distance, e.g., how do we judge these things?

Does RealD use the side-by-side or interleaved? Is that why DCI displays at 48fps? Does that mean I have to shoot at 48fps or can I shoot at 24/25/30/60?

It's too damn confusing.
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Old February 3rd, 2010, 06:14 AM   #4
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the frame rate is the regular one (24fps), it is only at display it is changed.
some will display frame interlacing (2x24=48), but some will go higher (up to 400Hz).
depends too, if display technology use interlaced frames or frame over frame.
Pure stereoscopic usually assume that both sides are displayed at same time.
So you need 2 projectors and the polarisation is supposed to allow each side to reach the correct eye. In that case 24 fps is what you get (or more if you shoot video 30fps for .
That is easy to do at home , since small DLP projectors a cheap, but most technology are trying to avoid 2 projection systems just because many theaters do not have the necessary equipement and upgrading is simply too expensive.
So they use tricks to upgrade regular projector into sterescopic system by adding some polarizer in front of it. Proceeding that way oblige you to send interleaved picture (one side then the next one). So, at least you need to double the frame rate to 48Hz, but the higher the better. RealD is using 144Hz, but it is not important since the projection system is dealing for that. You just need to provide you movie in regular 24fps.
the advantage of polarized projection is the glasses are cheap (less than $2 ea.) and can be give away, so you do not need to collect them and clean them.
The drawback of all polarized system is they need a special silver screen, something that usually does not exist in regular theater. So the next step is to provide display technology that does not require silver screen

Dolby 3D is more complex but use the same pattern, sending different picture at different time. The advantage of that is you do not need special silver screen and glasses are still on the cheap side. So from the economical point of view , it is a good system

Some other display technologies are using shutter glass instead polarized. Here again, the same principle. Different pictures sent at different time. But since the shutter is leaving an eye in the dark, high frequency are used to avoid blinking.
The drawback of shutter glasses is they are expensive (around $50), and contains electronics, so a battery is required, maintenance, failure , cleaning, broken/stolen glasses are all problems that theater do not want to deal with happily.

But strictly from the shooter/editor point of view, there is no standard that you need to apply regarding display system used (and probably you would not know the technology involved in advance, since each theater could use the one available).
On the other hand, there are a lot of rules to respect to get good stereoscopic picture.
Even there you are not sure it will fit anybody. for example, children sees differently from adults since their interocular distance is smaller than adults.
some of these rules could even be against the common rules found in movies, so, sometimes you have to make some compromise.
For example, 3D would prefferably require the all the picture is in focus, from foreground to background.
the is pretty unusual since DOF is heavily used in movies.
It is not forbidden to use DOF in 3D, but you need to take extra care, because for the spectator's eye, the picture is physically on one plane (the projection screen), and the eye is working to stay focused on that distance. But all the magic of 3D is to fool the brain (not the eye) to think it sees depth. The problem of doing this is that naturally, brain and eyes are working together. So if you play with DOF, the eye will try to compensate, as if the screen projection distance has been changed (while it is not the case).
So the result is some spectator will get an headache very fast.
So shooting 3D is much more demanding on how you want the viewer to read the picture and you have to capture his attention in a very effective way.
from the interocular point of view, you are very free, from half inch to 20 inches, all is possible. you just need to make sure you understand the effect of doing that.
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Old February 3rd, 2010, 10:42 AM   #5
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the bigger the interocular distance, the more you loose in framing.
One rule of 3D, is subject should not be located on the side of the picture, because it could happens that what is seen from the left eye, is not seen by the right eye. So you end up with a broken 3D (again , headache) . Keeping interocular distance small allows to use more of the picture width. But on the other side , the 3d effect is less obvious. So you need to keep balance.
You can also increase 3D perception by making interocular distance bigger. Very useful for large shoot (street, buildings), making image deeper.
Some shots are almost impossible in 3D, like shooting in a crowded corridor, with people located very close to the camera, on the side of the field of view.
You can do it , but you need to use some tricks, like using DOF, so the attention stay focused on some details in the center of the screen.
Good thing would be to use super large format (like the old omnimax or imax) so you are sure the side of the picture is almost out of sight of the spectator.
I think this point is almost the only one that eventually link you shoot with the display technology. You know that in some theater, all seats won't have the same value for viewing.
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Old February 4th, 2010, 06:36 AM   #6
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Thanks Giroud

Thanks for the detailed reply. When I saw Avatar the first time in IMAX, i sat in the extreme right, but I still didn't have issues with the 3D. What did Avatar do right? Was it the blocking/framing or did they really do something different that we don't know about yet?

Also, I watched Final Destination on DVD (the 3D Version), and it sucked. I have a 42" monitor and the 3D effect wasn't there at all. What am I missing?
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Old February 4th, 2010, 07:11 AM   #7
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in my city, Avatar is displayed with shutter glasses, so this system is less prone to disturbances due to seat positioning. Polarizing is a lot more sensitive to this.
usually 3d movie are projected in smaller rooms, to prevent people being seated too much on the side.
If you can choose your seet the best is to have the screen filling your field of view, but not being too close. for polarized system, you need to be the closer to the light beam, means usually high positioned in the room.
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