With Toy Story 1 and 2 currently doing the rounds in a brand new 3D format and Toy Story 3 scheduled for launch on June 18th 2010 we thought we'd take a look at a host of films the studios are re-releasing in 3D cinemas. Is this a great new way for us to enjoy some old favourites thanks to new stereoscopic visual aids (3D glasses to you) or just an easy way for studios to squeeze more money out of their back catalogue?

Shooting a new movie in 3D and converting a 2D film shot back when 3D meant laughing at Jaws 3 or wincing at Friday 13th Part III are two very different processes. For recent films designed specifically for 3D such as The Final Destination the film-makers shoot the action using two cameras to represent both eyes (in the case of Monsters vs Aliens, an animated film, the second camera view is much simpler to implement since the action takes place in a virtual world anyway).

Well, your mother did always warn you.

To calculate how far away the viewer is from the presented image requires the two cameras be set a certain distance apart. This separation is called the Stereo Base Line and results from the ratio of the distance to the cinema screen to the (horizontal) distance between your eyes.

Luckily with Toy Story 1 and 2 it was just a case of Pixar retrieving the original data and forming a second image set millimeters apart to create a new 3D version of the film. But with a film like Titanic, which is live action, that isn't possible so a new 3D conversion system had to be designed.

YOU...ARE...A...3-DIMENSIONAL...TOY!

"We can't call it dimensionalisation, we have to call it conversion," James Cameron explained recently at Comic-Con. "That's the same thing, we're going to turn [Titanic] into high quality 3D. It takes about a year to 18 months to do it depending on the complexity. We've been told somewhere around a year, maybe 14 months."

"We've tested it, seen a couple of minutes converted. It looks spectacular. But it really requires the filmmaker to be involved to make sure that the Stereo Space decisions are made correctly." The Stereo Space he's referring to means where in the frame the director places the focus of the 3D action, that is popping out the screen at the audience, in the mid-ground or seemingly far in the distance. Each shot has to be calibrated in this way to suit the story.