
308 Virtual Reality: Concepts and Technologies
different parameters of stimuli displayed on a cathode screen with active eyeglasses:
the colour, the display time, the vertical position on the screen and the positive or
negative parallax. The results imply that the limit of merging (given in angle of
parallax) is very low for a brief stimulus of 0.2 seconds: either 27 minutes of arc
(negative parallax), or 24 minutes of arc (positive parallax) compared with a stim-
ulus of 2 seconds: either 5 degrees (parallax < 0), or 1.5 degrees (parallax > 0). It is
therefore more difficult to observe rapidly moving 3D images. Red is easier to merge
than white (for ...