26-07-2012, 04:45 PM
How 3D Works
[attachment=29144]
Artificial 3D - recreating the 3D effect artificially
If we look at a standard flat TV screen, we're looking at a flat 2D picture. Because we have 2 eyes we can see the 3D characteristics of the TV box itself (e.g. how thick it is, and how far away from the wall it is, what angle we're looking at it), but there's no depth to the image displayed on the screen - it's just a flat array of pixels showing different colours. It's like looking at a photograph - a 2D snapshot of a place and time.
But it is of course possible for a TV to create the illusion of 3D. I call this "artificial 3D" because there isn't actually a 3D object protruding from the screen - it's still just a 2D array of pixels.
The key to creating an artificial 3D image is in feeding a separate image to each eye. This re-creates the 3D effect that we get when looking at the real world with two eyes. The brain takes the two separate images and combines them into one 3D image.
Of course this doesn't work with any two separate images... The two images must be carefully created and arranged so that they represent what each eye would see if it were looking at a real 3D scene. So, when the brain combines the two separate images (one from each eye), it is tricked into thinking that it actually is looking at a real 3D scene.
The basics of 3D filming
To film in 3D requires a 3D camera. And essentially that's just two cameras strapped together, filming two separate images at once. The left camera films the image for the left eye, and the right camera films the image for the right eye.
It's also possible to construct the two images required for 3D computationally. I understand that this was how the 3D version of Clash of the Titans was made (although I also understand the 3D effects in that film weren't particularly great). So I'm not sure that we'll be seeing 3D versions of many films that have already been filmed in 2D (e.g. taking Terminator 2 and making it 3D), but, given the right software, it's definitely pretty straightforward to make 3D versions of computer animated films. When a computer is generating one 3D image already, it's not a great leap to get it to generate a second 3D image from a slightly different angle (for the other eye).
The basics of 3D TV
Just like any other artificial 3D, 3D TV works by feeding a separate image to each eye, so that the brain can unite those two separate images into a 3D picture. The two separate images need to be carefully constructed so that they show the same thing but from slightly different angles, as this is what tricks the brain into combining them into a single 3D image.
The theory of 3D television is very straightforward - one image for each eye. But the technology required to actually implement it with detailed full-colour images is a lot more complicated. Because most people don't want to sit and watch movies that look like the animated Magic Eye picture above
Passive 3D Using Polarization
Polarized 3D, or passive 3D, is the technology that's typically used by cinemas to show modern 3D films like Avatar or Alice in Wonderland.
In a projection system, such as that at a cinema, two images are projected onto the screen, and each image is polarized in a different direction. You wear polarized glasses with lenses that are polarized in opposite directions, each lens matching the polarization of its corresponding image. The polarized lens covering your left eye is polarized to block the right image, and the polarized lens covering your right eye is polarized to block the left image. So your left eye can only see the left image, and your right eye can only see the right image.
Some 3D-capable projectors are actually comprised of two projectors - one for the left-eye's image and one for the right-eye's image. But many 3D projectors consist of a single projector running at a higher refresh speed, and alternately showing a frame for the left eye (with the polarization for the left lens on the polarized glasses) and a frame for the right eye (with the polarization for the right lens on the polarized glasses). Some very high-resolution single projectors can also display the left and right images together (i.e. no need to alternate between them).
How well does it work?
Polarizing technology works very well - you'll appreciate this if you've seen a 3D film in a good cinema with polarized 3D technology. And the glasses are cheap and light, which is good. But passive 3D doesn't seem to be the mainstream technology for home 3D.
Showing two images with different polarizations is a little tricky on a flat-screen TV, so, at the moment, passive home 3D technology typically requires a projector (keep reading though, as this is changing). For polarized 3D you can't just use any projector either... It needs to be a 3D-capable projector that uses polarizing technology as opposed to active-shutter technology (described in the next section). Most 3D projectors use active-shutter technology, so the polarizing ones are pretty hard to find for the home.
To use a polarizing projector you also need a special "silver screen", which has an aluminium coated surface that reflects light in a way that preserves its polarization. Silver screens are the screens that were traditionally used in cinemas, and that are making a resurgance again now that 3D cinema is becoming more popular. The trouble is that these silver screens cost several times more than standard projector screens.
Going the projector route, polarized 3D technology for the home appears to be a pretty expensive business that's really only for enthusiasts at the moment.
However, it's looking like passive 3D might actually take off on regular flat screens as well... LG are soon to release a 47" passive 3D LCD screen - the LD950. I believe this works by assigning half the lines of pixels on the screen to the left image, and half to the right image i.e. line 1 is for the left image, line 2 for the right, line 3 for the left etc. This approach does effectively halve the resolution when it's running in 3D mode, from HD to standard definition, but the cheap, light glasses make it a pretty appealing option in my opinion.
[attachment=29144]
Artificial 3D - recreating the 3D effect artificially
If we look at a standard flat TV screen, we're looking at a flat 2D picture. Because we have 2 eyes we can see the 3D characteristics of the TV box itself (e.g. how thick it is, and how far away from the wall it is, what angle we're looking at it), but there's no depth to the image displayed on the screen - it's just a flat array of pixels showing different colours. It's like looking at a photograph - a 2D snapshot of a place and time.
But it is of course possible for a TV to create the illusion of 3D. I call this "artificial 3D" because there isn't actually a 3D object protruding from the screen - it's still just a 2D array of pixels.
The key to creating an artificial 3D image is in feeding a separate image to each eye. This re-creates the 3D effect that we get when looking at the real world with two eyes. The brain takes the two separate images and combines them into one 3D image.
Of course this doesn't work with any two separate images... The two images must be carefully created and arranged so that they represent what each eye would see if it were looking at a real 3D scene. So, when the brain combines the two separate images (one from each eye), it is tricked into thinking that it actually is looking at a real 3D scene.
The basics of 3D filming
To film in 3D requires a 3D camera. And essentially that's just two cameras strapped together, filming two separate images at once. The left camera films the image for the left eye, and the right camera films the image for the right eye.
It's also possible to construct the two images required for 3D computationally. I understand that this was how the 3D version of Clash of the Titans was made (although I also understand the 3D effects in that film weren't particularly great). So I'm not sure that we'll be seeing 3D versions of many films that have already been filmed in 2D (e.g. taking Terminator 2 and making it 3D), but, given the right software, it's definitely pretty straightforward to make 3D versions of computer animated films. When a computer is generating one 3D image already, it's not a great leap to get it to generate a second 3D image from a slightly different angle (for the other eye).
The basics of 3D TV
Just like any other artificial 3D, 3D TV works by feeding a separate image to each eye, so that the brain can unite those two separate images into a 3D picture. The two separate images need to be carefully constructed so that they show the same thing but from slightly different angles, as this is what tricks the brain into combining them into a single 3D image.
The theory of 3D television is very straightforward - one image for each eye. But the technology required to actually implement it with detailed full-colour images is a lot more complicated. Because most people don't want to sit and watch movies that look like the animated Magic Eye picture above
Passive 3D Using Polarization
Polarized 3D, or passive 3D, is the technology that's typically used by cinemas to show modern 3D films like Avatar or Alice in Wonderland.
In a projection system, such as that at a cinema, two images are projected onto the screen, and each image is polarized in a different direction. You wear polarized glasses with lenses that are polarized in opposite directions, each lens matching the polarization of its corresponding image. The polarized lens covering your left eye is polarized to block the right image, and the polarized lens covering your right eye is polarized to block the left image. So your left eye can only see the left image, and your right eye can only see the right image.
Some 3D-capable projectors are actually comprised of two projectors - one for the left-eye's image and one for the right-eye's image. But many 3D projectors consist of a single projector running at a higher refresh speed, and alternately showing a frame for the left eye (with the polarization for the left lens on the polarized glasses) and a frame for the right eye (with the polarization for the right lens on the polarized glasses). Some very high-resolution single projectors can also display the left and right images together (i.e. no need to alternate between them).
How well does it work?
Polarizing technology works very well - you'll appreciate this if you've seen a 3D film in a good cinema with polarized 3D technology. And the glasses are cheap and light, which is good. But passive 3D doesn't seem to be the mainstream technology for home 3D.
Showing two images with different polarizations is a little tricky on a flat-screen TV, so, at the moment, passive home 3D technology typically requires a projector (keep reading though, as this is changing). For polarized 3D you can't just use any projector either... It needs to be a 3D-capable projector that uses polarizing technology as opposed to active-shutter technology (described in the next section). Most 3D projectors use active-shutter technology, so the polarizing ones are pretty hard to find for the home.
To use a polarizing projector you also need a special "silver screen", which has an aluminium coated surface that reflects light in a way that preserves its polarization. Silver screens are the screens that were traditionally used in cinemas, and that are making a resurgance again now that 3D cinema is becoming more popular. The trouble is that these silver screens cost several times more than standard projector screens.
Going the projector route, polarized 3D technology for the home appears to be a pretty expensive business that's really only for enthusiasts at the moment.
However, it's looking like passive 3D might actually take off on regular flat screens as well... LG are soon to release a 47" passive 3D LCD screen - the LD950. I believe this works by assigning half the lines of pixels on the screen to the left image, and half to the right image i.e. line 1 is for the left image, line 2 for the right, line 3 for the left etc. This approach does effectively halve the resolution when it's running in 3D mode, from HD to standard definition, but the cheap, light glasses make it a pretty appealing option in my opinion.