DIY Tardis looks bigger on inside with augmented reality

A US-based Doctor Who fan has built a model of the Tardis designed to look bigger on its inside than its outside.

Rather than circumvent the laws of physics Greg Kumparak has relied on augmented reality (AR).

The actual interior of his wooden model features a zebra-striped fabric.

But when a smartphone is held in front of it running an AR app, it appears to show a spacious interior modelled on the ninth and tenth Doctors' time machine.

Mr Kumparak, former mobile editor at the Techcrunch news site, said he decided to embark on the project over his Thanksgiving break.

He had carved the exterior out of wood, painted it blue and attached a working light to its top before coming up with the idea of creating the illusion that the inside was huge.

"There's a running gag in Doctor Who, wherein new characters are always dumbstruck by the Tardis being bigger on the inside than it appeared on the outside," he wrote on his blog.

"Once I realised I had a rough idea of how to pull that off, I couldn't not do it."

To bring his idea to life, the Silicon Valley-based designer first created a 3D computer model of the Tardis's interior using the free-to-use open source computer software programme Blender.

He then used the Unity graphics rendering engine - commonly used by independent video games developers - and Vuforia - an AR app development platform made by the chip maker Qualcomm - to allow a smartphone to interact with his creation.

The only problem was that the software needed to latch onto a specific part of the model to be able to map out the appropriate view of the Tardis's interior.

Mr Kumparak initially tried using the sign on the police box's door which says: "Free for use of public", but it proved to be too small to work.

So, he ultimately detached the front door and added a piece of material with a black-and-white pattern. The smartphone software could then use this to work out which part of its camera's image should be superimposed and what angle of the interior image should be shown.

Reaction to the invention has been overwhelming positive on Twitter and YouTube - a site notorious for attracting some of the web's harshest feedback.

"Insanely cool," wrote one admirer. "You have just made my Xmas," posted another.

One user suggested the inventor might like to add features - perhaps even allowing the Doctor and some of his companions to appear inside.

"The feedback has been resoundingly positive so far," Mr Kumparak told the BBC.

"Almost shockingly so, really. Doctor Who fans might be some of the nicest people on the internet."

He added that there might be an opportunity to develop the idea further.

"I originally made this just to brush up on a few new skills and to have something fun for my desk - that so many others got excited about it is really just a wonderful surprise.

"I've had more requests than I can count to make it into something others can obtain, be it as a store-bought toy or a printable kit.

"If anyone in the right department at the BBC is reading this and wants to make that happen, I'd love to lend a hand."