An Audio Analogy
3D video is similar in many ways to surround sound. Just as surround sound adds depth, placing you in the middle of the performance, 3D video places you, the viewer, in the action.
Just as we see the world with two eyes, we hear the world with two ears. Binaural hearing lets us sense the direction from which sounds are coming. Your brain processes the sounds detected by both of your ears. Without thinking, your brain will sense the difference in the time that the sound arrives at each ear, and the difference in the volume of the sound that each ear detected and you will have a sense for the direction that the sound came from. Our three-dimensional vision is similar to our three-dimensional hearing. We don’t have to think about the differences in the picture that each eye sees; we just sense the relative distance of everything we see.
When sound recording was first developed, each recording contained only a single channel of audio. Monaural recordings were later improved with two-channel stereo recordings. Two channels of audio provide an added dimension with respect to the apparent location of the source of each sound that is mixed into the recording. This “sound stage” allows recording engineers to arrange the relative position of instruments in a band, from left to right. When played back through a stereo amplifier and stereo speakers, the listener can hear a difference in relative volume coming from each speaker, and the relative timing of the sound for each instrument or voice. These differences give our brains an audible clue that helps us sense where the sound is coming from.
With a stereo recording, all of the sound appears to come from one general direction: the direction of the speakers. This is fine for reproducing music, as we are used to music coming from the direction we are facing when we attend a live music performance. Movies producers want their audience to feel that they are at the location that the movie is happening (in the room, or at the scene). To give the audience the feel of “being there”, multi-channel surround sound was developed.
Just as surround sound systems provide a more immersive experience, 3D video adds an important third dimension to movies and television.
Done well, 3D video provides an experience that feels real and natural. Clearly, audiences are excited by the experience, and they have shown a strong preference for seeing 3D movies in 3D cinemas.
Great article! Thanks! - Jon
core i5, gtx2 9800, nvidia 3d vision... am I good to go?
Anaglyphic 3d glasses FTW!
Also, you fail to mention that interlacing the image is highly impractical due to compression techniques.
You forgot the compatible Blu-ray player?
vesa connector for TVs
http://en.wikipedia.org/wiki/VESA_Stereo
Why do we still call them set-top boxes? I mean, its been years since a television has been deep enough or flat enough to sit the box on top of the set! At least, not without some form of super strong adhesive.
I've yet to enjoy a 3D film (and not just because Avatar was crap I might add). I think I may have issues with accomodation and blur disparity.
I was just looking as some samsung 3dtv's, they seem to have the ability to process 2d video such as standard non 3d tv transmissions into 3d video display.
How is that done without this info being in the video stream?
^ and is this also possible using nvidia graphics cards and shutter glasses?
This story is sponsored by Hollywood and all the film studios desperately trying to come up with something that will keep people going to the cinema. Notice how all films are 3D at the moment? Perhaps if they reduced the price of cinema admission and Bluray Discs, they would make enough money to stop feeding us this rubbish. Since most films will be viewed on standard TV sets, why would we want all that extra cash to be spent on 3D tech during the filming stage?
As an aside, did anyone see the film called Primer? Now THAT was a good film!
Indeed, lol, Primer was superb and was also funded on a shoestring!
A very well-written article, thanks! I would like to increase the scope of this paragraph, however:
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"Another important parameter is the angle of convergence. 3D camera lenses that are aligned in parallel will result in a picture where all objects appear to be in front of the TV screen (or display). Objects at an infinite distance will appear to be on the screen. To create a stronger 3D effect, camera lenses can be angled (converged) slightly inward. With this setup, objects at the distance where the optical axes of both lenses converge will later appear to be on the screen. Closer objects will appear in front of the screen, and farther objects will appear to be behind the screen."
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Converging the lenses causes keystone distortion that has to be corrected in post, if severe, and objects that reside far behind that point in the subject space where the lens axes intersect can appear doubled-up on screen. This requires the use of selective focus (large apertures that reduce the depth of field) so that the doubled-up background will be sufficiently out of focus.
Shooting with parallel lenses avoids these problem and there are several ways to prevent the entire subject space from being rendered in front of the screen, into negative parallax: A stereo camera can be designed such that the distance between sensors (or between film gates) is greater than the distance between lens axes. It doesn't take much shifting to the outside of center to push the rendered space behind the screen, into positive parallax. Cameras have even been designed with variable-offset film gates, so that the placement of the stereo window along the Z-axis of the subject space can be varied at will. Even in the absence of such equipment, when using cameras where the sensor or film gates is centered behind the lens, a stereographer can still shoot with the lenses converged at Infinity (with the lenses parallel), controlling the placement of the stereo window in post, by cropping a narrow, vertical strip from each frame (to mimic having used a proper stereo camera design that has variable offset sensors or film gates). This solution, is unfortuntaely accompanied by a slight loss of resolution.) Still, it avoids the less pleasant side effects of shooting with converged lenses.
Michael K. Davis