Science B13

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Ultimate Movies

By Arlon Staywell RICHMOND — As movie technology moves ever forward, or nearly forward, are you noticing the changing options? Have you any inkling how they work? Do you know what the challenges are in producing them?
Although 3D technology has been around for quite many years the quality has been improving and the costs of production are becoming more favorable.
Competing Systems
But there is no single system holding sway. There are in fact several different kinds of "3D" movie and you need to pay attention which ones are available in your area. They are based on completely different technologies and theories. The movies made for them often involve a style of writing that is as different as the photographic technology, perhaps not surprisingly.
Domes
Although they are not called "3D" and truly do not produce a different image, or different angle of view for various parts of the scene, for the left and right eyes, the "dome" theaters can yet produce stunningly realistic images that give the impression the viewer is positioned in the scene on the screen. This is because the viewer's entire field of view is covered by the screen. If the camera moves forward through the scene, things disappear off the edges of the screen as in any theater, but in a dome theater this means that things disappear behind the field of view; left, right, under and above, just as is the case when the viewer moves forward in a real life scene. And dome theaters typically use film with much more information, much larger film frames, in order to fill the much larger screens with sufficient detail. The advantage of this method is that it requires no special glasses. A person with only one good eye however unfortuitous that is otherwise can experience the movie, at least, as well as anyone else.
Color Filters
One type of "3D" that presents different information to the left and right eyes and the type with which most people are likely familiar involves those "red and blue" glasses. The new higher technology glasses might be "purple and green" but they work on the same principle if not perhaps much better. The 3D effect can be more stunning than the lighting seems natural. This is because color distortion can occur. Because neither the image to the left eye nor to the right eye is naturally colored, the brain of the viewer has to "compute" the composite or "natural" color. It does this of course without a conscious effort most of the time. Since it is also distracted following the plot and action of the movie it can slip and one or more colors might appear particularly unnatural.
Polarizing Filters
Newer technology involves polarized light. Because light is a wave, or because it is a "wave-particle" with wavelike properties if you prefer, there is a direction to the back and forth movement that makes it a wave or wavelike. A person holding one end of a long rope while someone else holds the other might for example move his own end of the rope up and down or left and right to get rope "waves" that are "polarized" up and down or left and right. Much as a third person might block with his arms either the up and down or left and right rope waves there are polarizing filters that block light waves except those with the correct orientation. Special glasses have such filters for each eye. The filter for the left eye only allows light waves polarized at a right angle to those through the filter for the right eye. This is within a certain tolerance that allows some tilting of the head. If you look at the glasses or through them at other than a 3D movie you can detect no difference between the left and right filters just as you cannot detect the direction of polarization of ordinary polarized sunglasses. They do work though. The projection of the movie involves sending correctly filtered light through two separate images, one for the left and one for the right eye to the same screen. The advantage over color filters is that each eye is receiving a "naturally" colored image. Polarizing filters allow all colors or "frequencies" of light nearly the same so long as the direction of wave motion is correct. The marked color distortions that can occur with the color filter method are thus avoided. A disadvantage is that the light source must produce much more light to take into account that only a portion of it will go through to the images. One of the limiting factors for the size of a screen is the heat and danger of the lamp required. Of course new theater centers often show several movies at the same time and those several screens are usually smaller anyway.
Liquid Crystal Display Shutters
Another method of presenting different views or angles of view to various parts of a scene uses liquid crystal technology similar to that used in pocket calculator displays. The special LCD shutter glasses alternately block all light to one eye then the other. It happens fast enough to avoid the perception of the flicker much as flicker is avoided in all movies, television and computer monitors. On the screen only the image for one eye at a time appears. The glasses must be carefully syncronized so that they are open and closed at the right time to present the correct image to the correct eye. The advantages are no color distortions such as might happen with color filters and without the need for the excess light that polarizing filters require. Serious disadvantages are that the glasses require either electric cells, "batteries," or a cord to power the LCD shutters and they need to receive a syncronization signal in order to match the timing of the various images. Such glasses can be expensive for the theaters to maintain. Their failure during a movie could be a big problem also.
Buyer beware
The "dome" theaters are usually noted as such. But a "3D" theater might use color filters, polarizing filters or LCD shutters and you might not know which over the phone or internet. Remember that all the methods work, but none are perfect. New computer technology makes it easier and less expensive to produce content for 3D theaters and it is important to see for yourself the progress made in quality.
Which technologies can be brought home
Some of the technologies can be made available for home theaters. Of course there isn't likely to be a home monitor that produces much polarized light at any low cost any day soon. And no giant dome is likely to be practical. But the color filter method and the LCD shutter method can work at home. The big advantage of the LCD shutter method for home theaters is that if you own a set you can take responsibility for their care yourself. The theaters don't have to worry about anyone stealing them or the batteries or breaking the cords, that becomes your problem.
And beware the writing
The sorts of movies made for the various technologies can be more about spectacular photography than the story or documentary. The "stories" might have no plot, no character development and the "documentaries" might have no outline of ideas. They might drift aimlessly from one "spectacular" photographic sequence to another. Please note this might bother writers more than other people. Some movies made for 3D and Dome theaters might have known, dependable content from a plain 2D run of the same movie. Check whether the whole 2D movie was transformed to 3D though, it might be transformed in a small portion only.
Near Richmond, Virginia
The Science Museum of Virginia in Richmond has an IMax Dome theater.
The Regal Commonwealth Stadium 20 in Midlothian, Virginia shows 3D movies on about one or two of its many screens using the polarizing filter method.
They also have a color filter or "IMax 3D" larger screen. The IMax 3D has been upgraded and can show polarized method movies on its very large screen.
In Hampton, Virginia at the Air and Space Center is an IMax theater that uses the colored filter method. That screen is not as large as the Domes, but it is much larger than many screens.
A Minor Hazard
People who wear bifocal prescription eyeglasses might notice that when "nearer" images appear in a 3D movie they subconsciously tilt their heads back a little to better focus on them through the lower portion of their bifocals. That doesn't work because the images aren't really nearer, all the images in a 3D movie are really at the distance of the screen. This could lead to a habit that can complicate use of bifocals outside the theater. Much depends on how well one accomodates the various situations. For example if you adjust well to water taps in your home that turn in different directions than other taps for on and off you might adjust better to other complications as well.

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