6th Dec 2010 | 13:30
The UK's first 3D TV channel has gone live, but watching 3D in the home is a roller coaster ride
You might have noticed a little buzz around 3D recently, and why not – 3D TV sounds like a fantastic idea. James Cameron's Avatar demonstrated that the technology has advanced, even if the film itself is a steaming pile of stinky old sci-fi cliches, and after some short but intriguing demos from Sky, we wanted to know how it would translate into an experience you could enjoy at home.
Sky has partnered up with LG for 3D, and we used an LG 47LX9900 active 3D TV. It retails at around £2,000, including two pairs of rechargeable glasses (extra pairs cost £100 each).
In 3D mode, the screen alternates at 50Hz between left and right eye images, and the glasses contain LCD filters which block each eye at the same rate, synchronised by an infrared signal from the TV. The brain is fooled into seeing a stereo 3D image.
The parallax view
Depth is defined by parallax; caused by the separation of the left and right eyes, and 3D stereo cameras mimic this, creating positive and negative parallax to make objects to appear in front of or behind the screen. Too much, or too fast, and your eyes will have to refocus uncomfortably.
Other factors can affect the 3D experience, such as image brightness and crosstalk, where the left and right images aren't cleanly separated so you see ghostly echoes. Ambient light also makes a difference: pitchblack is best as the glasses are highly reflective, and bright sunlight causes peripheral vision to flicker most unpleasantly with active 3D.
Then there's Sky's transmission format – side-by-side – which squeezes the left and right images into a single HD frame at 1080i, which the TV then stretches to full width. This means they're not 1920 x 1080i, but 960 x 1080i, although Sky claims that lost horizontal resolution is less noticeable than lost vertical detail.
Over two weeks we've watched a bit of golf, football, nature and film docs, some films, and we've seen Sky's 3D demo reel too many times. It's all free to Sky World HD subscribers, at least until there's a full schedule worth watching, and it works on existing Sky+HD hardware.
However, as yet there's no 3D Sky Guide if you want to look at it while watching in 3D. It's just very fuzzy. There's a huge variation in quality, and some of Sky's older 3D experiments, like the Avatar 35mm Special, should be locked in a heavy box and thrown overboard.
The nature docs Bugs! and CGI dinos of Sea Monsters made us look forward to David Attenborough's Flying Monsters 3D at Christmas. Monsters vs. Aliens had some fun moments, but some 3D effects designed for the big screen don't quite come off on TV, and when the effect goes wrong you stop enjoying the film.
Sky's sports are well-filmed, but onscreen graphics often pop jarringly out of the screen, especially with the deep landscapes of golf. And while depth was initially a bonus, especially looking at the subtly pitched greens, it was hard to decide whether it was any better than the BBC HD coverage, because of the half-HD resolution.
The 50Hz 3D refresh rate also makes movement far less smooth than 2D HD, when you can take advantage of the TV's 200Hz refresh. It's a backwards step, making balls and limbs disappear into a blur, and flattening the 3D image during tracking shots.
If we had a choice between 3D and 1080p or even 2K resolution, we'd take higher resolution. The 'wow' factor of 3D is short-lived, and it's too often a roller coaster ride from the 'oooh' of a nicely composed 3D image to the 'ouch' when your eyes suddenly cross over.
It's not good enough to buy a 3D TV. Not yet.
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