Stereoscopic image

A stereoscopic image is carried out by two optical sensors taking the same scene starting from two slightly distant points of view. These two sights can then be presented to the spectator so that the image of the left camera is seen only by the left eye, and the image of the right camera by the right eye to give an effect of Relief.

This effect of relief is produced by the Parallaxe. The Parallaxe is displacement between the two projection S of the same physical point, from a point of view of observation to the other. The stereoscopic cameras are usually adjusted so that the parallax corresponding to a point at the horizon is of 65 mm, i.e. the average distance between the pupils of an adult.

Types of acquisitions

Parallel cameras

Two cameras are used for the stereoscopic seizure of the scene. The distance between the cameras generally corresponds to the distance between our eyes (approximately 65 millimetres). This configuration requires two identical cameras with parallel optical axes (the line which passes by the focal point and the center of the sensors in the camera). With such an acquisition, the horizon will seem to be on the display screen and the various objects of the scene, will appear more close than the screen, in gushing.

Convergent cameras

This configuration requires two identical cameras. Instead of being parallel, optical axes convergent in a point which depends on the angle between the axes and the stereoscopic Base, spacing of the two objectives. It is this angle which must be adjusted in order to determine if the objects of the scene will appear behind, or in front of the display screen.

Stereoscopic posting

The Stereoscope

The Stéréoscope was the first stereoscopic posting with being invented. The stereoscope consists of a rectangular box of which the upper part is often open. Two openings, generally equipped with eyepieces, make it possible to observe the two images. In the middle of the stereoscope, a separator is placed between the images and the eyes of the spectator.

The Anaglyph

A Anaglyphe is a couple of stereoscopic images two complementary colors (usually red and cyan). If one records these two monochromic images on the same tape, one can separately visualize them with glasses which filter a color or the other for each eye, thus giving an impression of depth. This technique allows the stereoscopic diffusion of video color, but with restrictions.

The autostéréoscope

The autostéréoscope is a system where the images left and right-hand side are presented mutiplexées spatially on the same screen: the odd columns contain the left image, and the even columns the right image. In front of the screen another screen is which filters to create an impression of depth. Unless having a system of localization allowing the displacement of the user, this one must remain in the center to preserve this impression of profondeur.
See also: Car-stéréoscopie

Screen with polarization

The principle of polarization allows more flexible display systems. Here, the user carries polarizing, light and inexpensive glasses. The projectors are equipped with a device of polarization which encode the images left and right-hand side in perpendicular polarization. Polarized glasses then collect only the suitable image. This method allows the use of the colors and can be appropriate for a great number of spectators. It is a practical method for cinemas (IMAX), but it is also well adapted for projections to residence.

Temporal multiplexing

Posting with temporal multiplexing is adapted for viewing on a TV screen. Here, the images left and right-hand side are posted one after the other. Glasses of obstruction are synchronized with posting, making it possible to separate the images right-hand side and left and to create an effect of depth.

Stéréoscopie

Random links: