AVRover manufactures two types of portable stereoscopic 3D systems, active and passive. Both systems are projector based with 3D computers built in. They both run the same software and content. They both were designed with security, ease of setup and portability in mind.
The differences lie in the technologies that create the stereoscopic 3D effect. Since we are in the business of manufacturing portable AV systems, we do not have a particular preference for either technology, therefore our opinion is not biased towards one technology.
Passive 3D systems have been around longer, and most people are more familiar with them because this is the technology they have seen at the movies or in theme parks. The glasses are polarized, and with corresponding polarized filters at the projector(s), the separation of left eye and right eye imagery is then accomplished.
Active 3D glasses are a bit more involved in the process. They shutter their lenses on and off alternately in synch with the images on the screen that are showing left eye and right eye imagery in alternating frames fast enough so your eyes cannot see the opposite images, only the correct ones.
We use both technologies in our AVRover portable stereoscopic 3D systems, but the results are not quite the same, the costs are different, setup procedures differ, and the screen surface needed for each technology differs.
In a passive system, typically two projectors with polarized filters are needed, a special 3D silver screen is needed, but the glasses are quite inexpensive. Setup requires aligning the two projectors, which may take time depending on the ease of the alignment process in the system. The screen needs to reflect the polarization, so it is more expensive and not always where you need it. The glasses are not only cheaper, but they are always on, providing confidence that everyone is seeing the 3D effect. There is a slight ghosting that appears with passive glasses, and if they use linear polarization, the viewer needs to heep his/her head level for the glasses to work. Circular polarization can eliminate this problem.
Active systems use a single projector, which costs less and sets up quickly with no need to match the alignment with another projector. There is no ghosting, which means the images seen by each eye are only the images intended for that eye. The glasses are quite expensive, so if there is a large audience, the cost of the glasses can be significant. If a viewer looks away from the screen for more than a second or two, the shuttering can get out of synch. The active system will work on any screen surface - even a plain white wall. Finally, the batteries will eventually die and need to be replaced, or recharged if they are rechargeable, so the presenter cannot be 100% assured that the 3D effect is working for all of the viewers.
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