Man always sees the surroundings in 3d. We are used to the fact that the world is three-dimensional. Therefore we perceive our surroundings based on knowledge of a number of aspects, which signal spatiality. E.g., reading the size of an object - we know that a house which is seen as very small must be far away. Viewing it with two eyes each giving an image of the house, also matters in perceiving the three dimensions. When producing 3D worlds in our facilities the VR technology cheats the eye to view something else than the reality. This is done in several ways at VR Media Lab.
By visualization in mono both our eyes view the same image at the same time. This technique is know from the traditional monitor screen.


© VR Media Lab


It is possible to achieve a fairly good 3d effect by using mono, but the effect is increased substantially by using stereo thus generating separate images to each eye. When using stereo it is possible to an even higher extent to feel that the virtual world is either in front of the screen or behind the screen.


© VR Media Lab

In most presentations VR Media Lab uses stereo visualization, which uses two techniques: passive and active stereo. Each technique has its own advantage and disadvantage.

A presentation in passive stereo needs special glasses. These glasses look like sunglasses and are very light which clearly is an advantage.

One glass lets in light polarized vertically , while the other lets in light polarized horisontally. In this way it is possible to project separate images to each eye simultaneously. However, to do this it takes two projectors each projecting their image with individual polarization at the same time.


© VR Media Lab


However, the screen in the 3d auditorium makes it necessary to use 3 projectors to each eye to cover the whole screen, which again causes a considerable increase in the costs of the installations.

When using active stereo we also use special glasses, so-called shutter-glasses which are larger and heavier than the glasses for passive stereo. The shutter-glasses are synchronized by infra-red signals in such a way that each glass "opens" and "closes" for either the right or the left eye 60 times/sec. One actually looks with alternating eyes without noticing it. This is used to cheat the eyes and making a convincing spatial image.


© VR Media Lab


We have the possibility of adding yet another dimension to the visual trick. By means of a "tracker" on the glasses we are able to define the visual angle of the image as an electromagnetic field causes the tracker to report its actual x, y, and z coordinates whereafter the image is calculated and presented from this particular coordinate.