The problem of active vs. passive technology is one currently playing out in movie theaters as well.

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Unfortunately, Vizio hasn't committed to a 2013 release date for glasses-free 3D, but the rest of the lineup, set to debut later this year, will still have the firm's glasses-dependent passive 3D technology.

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The underlying technology enables both passive measurement and actively targeted marketing, but the privacy issues surrounding both are markedly different.

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These "passive" 3-D technology systems put most of the technical heavy lifting on the TV screen -- instead of on the glasses, as was the case with older models.

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The system Google is likely to unveil is known within the technology and music industries as a "passive" locker.

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Eleven of Sharp's large screen AQUOS models feature full HD 1080p active 3D technology, delivering twice the resolution of passive 3D.

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Sebastian Coe, chairman of the London Organising Committee of the Olympic and Paralympic Games, thinks the strides made in technology means that by the 2020 Games there will be no such thing as a passive armchair fan.

CNN: July 24, 2012 -- Updated 2201 GMT (0601 HKT)