In film, the term 3-D (or 3D) is used to describe any visual presentation system that attempts to maintain or recreate moving images of the third dimension, the illusion of depth as seen by the viewer.

The technique usually involves filming two images simultaneously, with two cameras positioned side by side, generally facing each other and filming at a 90 degree angle via mirrors, in perfect synchronization and with identical technical characteristics. When viewed in such a way that each eye sees its photographed counterpart, the viewer's visual cortex will interpret the pair of images as a single three-dimensional image. Modern computer technology also allows for the production of 3D films without dual cameras.