the effect by which the position or direction of an object appears to change when the object is seen from different positions 视差(从不同位置观察物体所产生的位置或方向上的差别) Word Originlate 16th cent. (also in the general sense ‘fact of seeing wrongly’): from French parallaxe, from Greek parallaxis ‘a change’, from parallassein ‘to alternate’, based on allassein ‘to exchange’ (from allos ‘other’).