3D technology has existed for more than 100 years and has had its ups and downs with another rise in popularity in 2009 with the release of Avatar 3D.
This technology takes advantage of stereoscopic vision to create the illusion of depth. The illusion is achieved by feeding two different images at different perspectives to the left and the right eyes and the brain takes the two images and processes them to complete the illusion.
In the early days, the only way you could watch a 3D movie or play a 3D game was in a theater or a theme park but things have changed as you can now do this in the comfort of your home. But with the discontinuation of 3D TV manufacture in 2018, you are only left with one viable option, using a 3D projector.
3D projectors work under the same stereoscopic vision principle to deliver different images to the left and right eyes for a 3-dimensional illusion.
This can be done using Active or Passive technologies to achieve the 3D effect.
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Active vs Passive 3D projectors
A 3D projector can use either active or passive 3D.
Active 3D works by displaying images for the left and the right eyes in alternation left to right to left and so on. This is done over 120 frames per second at a 1080p resolution with each eye getting 60 frames per second.
You will need active shutter 3D glasses for an active projection which darkens from left to right or vice versa in tandem with the projected images. If the projected frame is meant for the left eyes the right lens is darkened with the help of a chip and vice versa.
Passive 3D, on the other hand, works by projecting 2 blended/interleaved frames as one which can then be picked up by passive glasses. The passive glasses are made in such a way that the left lens can only pick up frames meant for the left eyes and the right lens for the right eye frames.
For passive 3D to work, the footage needs to blend cyan and red-colored frames or frames different polarizing light.
Glasses that can pick up red and cyan frames are known as anaglyph glasses. They are made or 2 cyan and red-colored lenses. The red lens only allows the red light to pass through and the cyan lens filters out the red light only allowing the cyan frames through.
There are also polarizing glasses that can pick up the differently polarized frames. These frames have polarized light waves that are projected in different directions for the left and right eyes. Therefore, one lens can only allow horizontal frames to pass through for one eye and the other lens only allow vertical frames to pass through.
For passive polarization, you will need a dual projector and each projector should have a polarizing filter or a single projector with dual-polarized lenses and a special silver screen. This is the most expensive 3D projection set up of the three.
Active vs Passive 3D comparison table
|3D projection||Passive 3D||Active 3D|
|Brightness||The brightness is reduced by half as only half of the light from the projector reaches each eye.||Brightness is also cut by half as one lens is always blocked from the light for each frame.|
|Resolution||The vertical or horizontal resolution is reduced by half for each eye as the image is split.||A full-resolution image is delivered. The resolution is not altered as the frames are delivered in alternation.|
|Crosstalk (images look superimposed)||The crosstalk effect is less common in passive projections.||This ghosting effect is common for active 3D projections.|
|Comfort level||Passive glasses are lighter and are more comfortable as there is no flickering.
There are fewer effects from using these glasses but a user can feel nauseated at times.
|Active glasses are heavier and less comfortable due to flickering caused by the darkening of the lenses.
This can cause different issues for some people such as nausea, dizziness, and headaches.
|Motion||The motion seems smoother as the frames are projected simultaneously.||Although the alternation of the frames is fast, your brain may pick up this sequence, the motion perception may not be as smooth.|
What is the difference between 3D-ready and Full-3D projectors?
3D-ready projectors are projectors that can only handle active 3D from a Frame Sequential bandwidth (1080p120). These projectors can only get their transmission from a handful of drivers usually Nvidia drivers. Other sources such as 3D Blu-ray players cannot work with a 3D-ready projector mainly due to licensing issues by Nvidia.
Full 3D projectors can handle all 3D transmissions and are compatible with all 3D sources such as 3D Blu-ray players, Set-top boxes, 3D streaming services, computers with 3D drivers (including Nvidia), gaming consoles such as PS and Xbox, and so on.
So, what are these transmission formats?
3D transmission formats
As you can tell by now, transmitting 3D content requires a lot of bandwidth which is done using HDMI 1.4 cables and up.
There are 4 standard formats used to transmit 3D bandwidth and they include;
- Frame sequential
- Frame packing
- Side by side and top to bottom
1. Frame sequential
This 3D delivery format is also known as page-flip and it involves transmitting a full 1080p resolution 3D image at 120 FPS. The frames at displayed in alternating sequence with 60 frames going to the left eye and the other 60 frames going to the right eye.
This format can only be delivered using a computer with an Nvidia 3D graphics card to a 3D ready or Full-3D projector.
2. Frame packing
Frame packing is somewhat similar to frame-sequential in that it sends 2 full 1080p resolution images at 24 frames per second for each image. These frames are packed on top of each other with a narrow 45-pixel black band between them.
This doubles the vertical pixel to 2160 pixels plus 45 pixels to a total of 2205 vertical pixels.
3. Side by side and top to bottom
With side by side and top to bottom transmission, the left and right frames are packed next to each either side to side or one on top of the other. This is done by reducing either the vertical or horizontal frames by half.
For example, a 1080p 3D footage is halved to 960 by 1080 pixels with side by side or 1920 by 540 pixels for a top to bottom transmission. During decoding the frames can then be stretched out for projection.
This transmission format involves interleaving two frames each for either the left or right eye into a single frame and reducing the resolution for each frame by half.
What is the difference between a standard and a 3D projector?
A 3D projector offers a more immersive experience when compared to a 2D projector by adding an illusion of depth. You easily get lost and carried away but whatever movie you are watching, documentary or game. However, not much content is tailored to 3D enthusiasts, especially if you live in the US you may need to buy region free Blu-rays from places such as the UK.
When compared to standard 2D projectors, 3D projectors and setups are significantly more expensive. This is because you may need a special silver screen for polarized content.
You also need special glasses to view 3D content. These glasses can ruin the experience for most people, especially with active shutter glasses which use batteries and chips that make them heavy.
Discomfort is common with 3D and can range from dizziness to headache. This mainly happens with active 3D due to the flickering effect, especially if the projection and the shutter on the glasses are out of sync.
3D projectors need to be brighter than 2D projectors. They need to have at least 3000 lumens as the brightness is greatly reduced by the glasses when filtering the frames for the left and right eyes which also filter out some of the light.