Looking into the idea of impossible spaces today I came across a journal article in VISUALIZATION AND COMPUTER GRAPHICS, VOL. 18, NO. 4, APRIL 2012 which outlines a series of research experiments into how a virtual reality ‘tardis’ could be created within a small physical space by means of impossible virtual spaces. The experiment used a physical space roughly 9 x 9m wide but the virtual space created was much bigger than this and the the participants wearing a virtual reality headset could physically walk through the virtual space [whilst also walking in the physical space] but without ever reaching the edge of the 9 x 9m physical area.
The act of using physical motor functions of the body to explore a virtual reality space adds to the experience fo the space and the immersion in it. But previously to be able to do this large spaces of the same size as the virtual space were required to allow for the participant to move continually around the space without obstruction. This piece of research develops on existing techniques of stretching or shrinking the space virtually as well as introducing a new field of research into overlapping spaces, impossible spaces in the real world. Using this technique two rooms can be overlapped in the virtual space so when the participant exits one, goes through a transition space like a corridor and enters the adjoing room part of theat new room will be sitting onto tof part of the old room in the physical space. This means in the physical space the participant will walk over the space piece of floor whilst in both rooms. This allows for a larger virtual space to fit into a smaller physical space. The research aim was to figure out how much they could use this, and other techniques, to compress the virtual space.
The experiement concluded that two virtual spaces filling the physical 9 x 9m space could overlap by 31% before the participants were aware that something was wrong with the arrangement of the virtual world. This amount went up to over 50% overlap when the space was split up into a number of smaller spaces. Therefore the participant exploring the space has no idea they are walking over the same points in the physical world and are tricked into thinking they have travelled much further and explored a much larger, impossible space.
Other techniques for stretching or compressing space in the virtual world are, translation gain, rotation gain and curvature gain. Translation gain means that when the participant is physically walking the visual virtual reality they experience either moves faster or slower to translate the movement into a shrinking or growing of the space. Rotation gain is very simlar but works when the participant rotates their body or their head, the display they are viewing moves faster or slower to adjust the space accordingly, using this technique the participant can think they are walking in a winding s shape route, when in reality they are walking in a figure of 8 in circles. Curvature gain works by making the participant think they are walking in a straight line in the vrtual world, but by a slight distortion of the view the participant is actually walking in a large arc shape. The arc must be larger than 22m in radius, any lower than this and the participant will start to percieve it as a curve.
All of these techniques work to create impossible virtual spaces within a smaller physical space, but as the participant doesn’t percieve these changes and impossibilities and they are physically moving through and exploring the extremities of the virtual space does the impossible space become possible. If the participant can explore ever area of the impossible space than it is no longer impossible. A tardis has been created.