WIDE-ANGLE SHOT OVER 3D

How 3D works

Almost every modern method of creating a three-dimensional image is based on the physiological features of human eyesight. Our eyes are located at a distance of 60–70 mm from each other, which allows us to see the world from two positions simultaneously. As a result, the left and the right eyes receive images of the same object at different angles.

These images are called a stereopair. Analysing the difference between the images received, our brain makes an assumption about how far away from us the observed objects are.

To create a 3D effect in the cinema, the principle of separate viewing is applied: an image is shown to each eye that is intended for that eye only.

The separation itself occurs in various ways, each of which has its own pluses and minuses.

Anaglyph

This method is simply what most people know as classic 3D.

The technology is over a hundred years old. It is based on the biological structure of the human eye. On our retinas, there are three types of photosensitive receptors — cones. Each type perceives only one of the primary colours: red, blue, or green.

The illusion of depth is achieved by dividing the image into two channels. For example, red and turquoise which is a mixture of blue and green. So, the resulting layers are superimposed with a slight shift. The viewer, using glasses with lenses of the same colours, receives a separate monochrome image for each eye.

The method’s main drawback is incomplete colour rendering. The image is perceived as single-tone or achromatic. The viewer quickly gets used to the effect. However, returning to the real world from a red-blue one is sometimes very painful.

In its classic form, anaglyphic 3D is almost never used. However, its successor, super-anaglyph, continues to be used in Dolby 3D technology. In the new design, single-tone lenses are replaced by special interference filters, which lessen the distortion of colours to some extent. But for all that, the technology continues to lose its fans.

Interlaced method

An image for one eye is recorded in even, interlacing lines, and in odd lines for the other. The result appears as a full-colour image with a ‘comb’ effect. The imitation of three-dimensionality is achieved by combining images using deinterlacing, a technology for creating a single frame from two half-frames of the interlaced format for output to monitors with non-interlaced scanning.

The image’s vertical resolution is reduced by half, while its colour rendering is retained in full.

This method is rare. It was previously used in making 3D DVD discs. Today it is experiencing a second wave of popularity, now with a passive separation of camera angles in 3D monitors. Even lines are passed through one kind of polarisation, while odd lines pass through another. All you need for viewing is simple, affordable polaroid glasses.