use of parallax vision in virtual reality systems

Parallax vision comes from the fact that human eyes see real world elements from two different angles. Eye muscles and cognitive analysis of the human brain work together to combine these two different pictures into sensation a single picture three-dimensionally. Muscles of each eye change the shape of each the lens to focus at the distance of the object viewed. Other muscles change the orientations of one's eyes so that lines of vision from both eyes intersect at that same distance. In real world sight, these two muscle functions work together. In Virtual Reality (VR), they may conflict. When pictures are displayed at great distances, then the size of the screen needed for immersion is overly large in size and it is a challenge to present different pictures to one's eyes. When images are displayed very near to the eyes extremely high picture resolution is required and the two muscle functions of one's eyes tend to conflict. The page on Virtual 3d discusses additional applications.

An object's inner edges can convey 3D angle and rotation. When distances between inner edges are shrinking, then this suggests that these surfaces are seen at an increasing-acute angle and "moving away". When the inter-edge distances are growing, then this suggests that these surfaces are travelling nearer to a right angle view and "moving nearer". Accordingly, an object with inner edges narrowing on one side and expanding on the other half seems to spin three dimensionally. Early 3D graphics used such effects to make "wire" figures that seemed to spin in three dimensions. Three-dimensional graphics are much more sophisticated now, but the geometry of object outlines remains core to depth sensation. More: Virtual Tours Hopkins, Minnesota has novel developments on this topic and virtual reality.

Virtual Reality VIsion also covers some of this VR material.