Stereopsis is derived from the parallax between the different images received by the retina in each eye (binocular disparity). The stereoscopic image depth cue depends on parallax, which is the apparent displacement of objects viewed from different locations. Stereospsis is particularly effective for objects within 5 m. It is especially useful when manipulating objects within arms reach
Thanks to VR, it is is now possible to manipulate very distant objects. But if we want to let that manipulation be easy to do, we need to virtually bring back objects within the stereostcopic area of our view !