Primer: The Principles Of 3D Video And Blu-ray 3D
Table of contents
- 1. What Is 3D?
- 2. Depth Perception
- 3. Depth Perception, Continued
- 4. Stereoscopic Vision
- 5. Shooting 3D Video And Animated Movies
- 6. Encoding And Delivering 3D Video Content
- 7. 3D Displays
Today we're partnering up with the experts at CyberLink to introduce the principles underlying 3D video, how it is created, and how it's displayed. Our main interest is Blu-ray 3D, so we'll be exploring the tech your 3D-enabled home theater might include.
Tom Vaughan is the director of business development for CyberLink, developers of the leading Blu-ray player software, PowerDVD. He is responsible for marketing, strategic relationships, and new business development in the US. When the DVD format first emerged, Tom was responsible for developing the DVD authoring and mastering processes, managing the production of some of the first commercial DVDs in the US. Tom holds a B.S. in Electrical and Computer Engineering and an M.B.A. from Drexel University.
What Is 3D?
3D is an abbreviation for “three-dimensional.” Objects in the real world can be measured in three dimensions; for example, by measuring the length, width, and height of an object. When we look at objects in the real world, we can see the width and height of an object (the two-dimensional view of the object), but we can also perceive the depth and distance of the object.
We see the world with our two eyes. Because each eye is in a slightly different location, each sees a slightly different perspective of whatever we are looking at. We don’t normally think about these two different views, but if you close one eye at a time, you will see the image that each eye sees. Notice how much different nearby objects appear from the view of each eye.
Although each eye sees a different image, we don’t perceive two images. In a process called stereopsis, our brain combines the view from each eye into a single picture, and the combined image includes three-dimensional objects and depth perception. The word “stereopsis” is from the Greek words stereo, meaning “solid,” and opsis, meaning “sight.” Stereopsis was first described in 1838 by Charles Whetstone, but scientists and artists have been fascinated with three-dimensional perception for many centuries.
While most of the population can see 3D, a small percentage of the population (estimates range from 3 to 15%) suffers from some stereoscopic vision impairment. Depending on the quality of the 3D presentation, this population will see no 3D effect or limited 3D depth perception. There are a number of possible causes for this, from decreased vision in one eye, to the loss of the ability to point both eyes inward towards nearby objects.
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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