3D
Originally posted by howlin_mad
Yeah, it would be cool to see the classic rides and shows to be put onto DVDs. They could also do the stuff easily in 3D and just include a pair or two of 3D glasses. The regular 2D image would look normal to everybody, and if you used the glasses you would see the 3D effects. They use this technique for the America's Greatest 1 and 2 and World's Greatest Roller Coasters videos.
I'm not sure that you understand the 3D effects techniques used for the Disney attractions and your Roller Coasters videos.
The Disney attractions where photographed in "true 3D," or, with two parallel cameras. The end result was based on the effects created by polarized glasses, filters, and dual projectors. Although it may seem complicated, I will try to describe this science:
Left camera > film projected through H filter > left lens on glasses is H filter
Right camera > film projected through V filter > right lens on glasses is V filter
Think of the different filters as H (Horizontal lines) and V (Vertical lines), or positive and negative. When your left eye looks at the screen through the H filter, it can only see the image that's being projected through the same H filter up in the projection booth. This is because H cancels out V, and vice versa. Thus, with both eyes, you're looking at a 3 dimensional image on screen, that is, visually acknowledging all 3 axis, x, y and z. A person who is blink in one eye does not experience 3D effects.
If you close one eye while watching a true 3D film, the film will become clear (but not 3D). If you tilt your head to the side, the images will become blurred, as though you were not wearing the glasses at all. This is because the H and V filters on your glasses are no longer aligned properly with the filtered images on screen, that is, perpendicular to one another.
Understanding this, you see how it is impossible to create a true 3D video that, while it looks 3D to those with glasses, would look normal 2D to those without glasses.
It should also be noted that true 3D projections onto a theater screen are a completely different science from television screen effects. Televisions cannot (to my knowledge) produce seperate H/V filtered effects. Rather, they use a "flicker" technology that, instead of overlapping the 2 (L/R) images, they display them interchangibly - very rapidly (thus "flicker"). This requires special electronic glasses that are bulky and run on battery power.
There are also those old blue/red cardboard glasses that one would see in theaters way back when, but those work on color spectrums and are completely unrelated to true 3D effects.
The science used on the Roller Coaster videos is in a breed of its own. You may recall the time when NBC's 3rd Rock from the Sun aired a "3D" episode. Glasses could be picked up at your local Burger King. These effects are created by filming with 1 camera and relying on time delay of light on the retinas. While those watching without glasses see normal tv, those wearing the glasses see "psuedo 3D." Those producing psuedo 3D films/television must keep this in mind during filming - and film with as much (fluid) camera motion as possible. This camera motion should be in contrast with the background. On a roller coaster, this effect is created automatically.
The effect is also enhanced when objects in extreme foreground move in contrasting direction or speed with objects in the background. One of the 2 lenses in your glasses is tinted, which very briefly effects the speed of light as it reaches your eyes. The delay of light reaching one eye creates the effect. The best way for someone to experience this is - buy a pair of sunglasses at the dollar store, and knock out one of the lenses, then watch tv - any show will do, but the effect will be more obvious with some programs than with others. If you have a movie that includes scenes in which it is snowing, the snow will appear slightly "3D," or, seperate the background. The snow is moving downward, while the backround is not, thus the contrast in motion. The snow may also be in the foreground, which enhances the effect as discussed. Again, anyone can try this - don't be discouraged if you don't notice any effect right away, just switch between programs - it's pretty neat.
If you're wanting to videotape a true 3D movie/attraction, you'll need to take one of those 3D glasses and cut out one of the lenses, affixing it in front of your camera lens. Be sure to keep the lens parallel to the ground, which should be easy because of it's rectangluar shape. This is to ensure that the filter type lines up with the image on screen. The video camera will cancel out one of the 2 overlapped images on screen, creating a single, clear image.
Cool?:sohappy:
Tk
