So, you make a deal with stereoscopic every day (if you have 2 eyes). Human has
binocular vision and it helps to perceive depth, which in turn help us to navigate in space better.
Lets have a look how our eyes and brain make a depth effect.
Just remember when you looking to side window in running car and see the trees which moving
with different speed relative to each other and feel depth, you see the parallax.
But if you look on you hands or something else closer you feel depth, its because parallax
too. Parallax help us to feel depth. Basically your brain receive two images in different angles and
connect its together into one volume image.
How people use this ability? Humanity invent stereoscopic cards or stereoscopic
photography long time ago.
Interocular or Interpupillary distance (IPD) or interaxial distance or interlace: it is distance between
centre of camera lenses in stereo pair (often measured in mm) average human have 63,5 mm.