**4. Stereo technologies**

Anaglyph technology is achieved by two identical, differently filtered images, respectively for each of the eyes [7]. The two images are placed on the screen with a slight offset from each other. No specific equipment is required here, just a pair of anaglyph glasses. This technology is most commonly seen in magazines and in the past when showing movies in movie theaters. 3D polarizing technology uses two images: for the left, and for right eye, they are superimposed on the screen before they pass through polarizing filters. Polarization is 45 for one eye and 135 for the other. There are two filters here, one for each eye [7]. The necessary equipment is two projectors aimed at the same screen; a polarizing filter is placed in front of each projector, allowing light to pass through. Shutter3D technology—with it, the frame alternates sequentially, first for one eye and then for the other eye; the frequency is 120 Hz by 60 Hz for each eye [7]. For this purpose, active shutter glasses are used, which darkens the glass of the eye, which should not receive information. 3D Display technology improves the perception of the 3D scene, from which the applications become more qualitative. Different 3D technologies are suitable for different applications, so it is important to know them thoroughly [4, 8]. Generally, these technologies are classified into two categories: stereoscopic and real 3D. The stereoscopic technique is based on

*Virtual Reality in Stereometry Training DOI: http://dx.doi.org/10.5772/intechopen.107422*

binocular parallax by presenting separate images [4] to each eye. Motion parallax can also be simulated by adding a head tracking system. Unfortunately, not everyone can perceive 3D information through 3D Display technology, as (2–3% of the population are stereo blind) [4]. In turn, stereoscopic displays are divided into two subclasses: stereoscopic and autostereoscopic. With autostereoscopic displays, the user does not need to have special 3D glasses. Stereoscopic displays are based on blocking each eye from seeing the image corresponding to the other eye. This is achieved through glasses using various Display technologies. They are mainly used for simulation and training. Many of these 3D scenarios are impossible or too expensive to simulate. Because most of them are too risky to simulate or too expensive. To be as realistic as possible, it is necessary to use immersive 3D systems. Low-cost 3D stereo displays are used in middle school student learning. The aim is to increase the level of understanding on the part of the students.
