To achieve fluid movement and high quality, real-time rendering must occur at a rate of at least 12 images every second. In addition, certain properties of materials can be portrayed, as can transparency. This method of generating images makes the picture of the vehicle seem as realistic as a photograph. The developers use special glasses to attain the sort of depth perception needed for working in the virtual world. Experts call this phenomenon stereovision and distinguish between active and passive forms of stereovision.
Polarized light is used in passive stereovision.
The principle is similar to that of 3D glasses, which are equipped with red and green filters. As the images projected onto the screen represent the object as seen from a slightly different angle, the designers see a blurred image of their virtual model when they look at the screen with the naked eye. The viewer sees a clear three-dimensional image as a result of this process. Because of the special glasses, the user perceives these projected images as being real. Tracking means that every change of the user's perspective or position in three-dimensional space is relayed to the computer.