There are a number of techniques that can be used to create stereoscopic, or 3D effects. Early forms of stereoscopic 3D were developed in the late 19th century as part of experiments with photography and the projection of light. While not being fully implemented into screen technologies like cinema in the early 20th century, specific forms of 3D were introduced as parts of 3D waves in the 1950s, and the more recent expansion of digital 3D for film, television, and video games.
Anaglyph and Polarisation
Early forms of 3D used both anaglyph and polarization technologies to establish depth. Anaglyph 3D relies on forms of additive light and colored filters to create the illusion of depth for a superimposed image. Red and cyan lenses in a pair of glasses combines color fields, while moving the head while viewing will enhance the effective. Associated with cheap cardboard glasses, anaglyph 3D is also used in photography and card effects. However, polarized 3D systems are more commonly used for film presentations.
Polarization involves the projection of two images onto a screen through filters, with 3D glasses using different polar light filters to produce an overlaid image. Different glasses types include linearly polarized lenses, which match up to a projector, but do require a viewer to maintain the same viewing angle. By comparison, circularly polarized glasses rely on analyzing filters to allow for the same 3D effects to be created without the need for stable head movement.
Current forms of 3D that work from digitally produced prints tend to come under the RealD category. Using circular polarization, the technology allows for head movement, but does experience problems with brightness. The projection and lens technology essentially reproduces the same effects as traditional polarized 3D, but improves on the need for dual projection. Other forms include Dolby 3D, a more expensive version that uses interference technology to control a larger spectrum of colors. Other notable techniques for creating 3D images include the Pulfrich effect, which relies on a filter being placed over one eye to make a flat object’s movement on a screen seem to be closer than it actually is.
Current 3D techniques can therefore be separated by the effectiveness of their depth effects in relation to the comfort and the cost of watching and projecting images. RealD makes up for the cost of special projection with cheaply polarized glasses, which in turn build on forms of linear polarization to prevent the best reduction in nausea from head movement. However, recent efforts have also been made to introduce glasses free 3D for home use, in doing so creating better comfort and flexibility.
How to get around wearing glasses has always been a concern for 3D television developers. New technology has looked towards using lenticular and parallax filters on the screen to send out a number of images, which are then read by different eyes and from different angles. By producing multiple images from the same source image, this process promises to enable 3D viewing from different angles. However, the technology remains out of reach for the average user, with glasses free 3D televisions currently priced at around £7000 ($11K US) in the UK.
Rob James is a technophile and loves the many different methods of watching TV. He likes to watch TV online with Time for Telly. Rob likes to blog about the latest technology gadgets and gizmos.
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