But what is 3D? This is the acronym for the term three dimensions. Movies have always had only two dimensions, height and width. However, with 3D technology, depth perception has become possible, which is the third dimension, which makes the image more real.
For the image to be formed in 3D, two sources of vision are needed, in this case, our eyes. Each eye sees the image differently, which is known as binocular vision. This is what makes us able to see the objects around us in 3D.
In cinema, this image is formed thanks to a phenomenon called stereoscopy, which consists of projecting the image of the same scene at different observation points. The brain receives these images, merging them into one. During this process, information about the position, size and depth of objects is obtained.
However, the image is not seen clearly if the 3D glasses are not used. The image is formed by two different projectors, one of which emits the image with horizontal light rays, and the other, with vertical light rays. 3D glasses use a technique based on the polarization of light. Polarizing light means making it propagate in only one plane. Each eyeglass lens has a different polarization filter: one lens filters vertically polarized waves and the other horizontally.
In this way, each eye receives a different image, and the brain joins the two images, forming a third image, which allows the perception of depth in the scene.
