Virtual reality helmet
Modern virtual reality helmets (HMD-display, head-mounted display, video helmet) contain one or more displays that display images for the left and right eyes, a lens system for correcting image geometry, and a tracking system that tracks the device’s orientation in space. They are now similar in appearance to glasses, so they are increasingly called VR headsets or simply virtual reality glasses.
They can be divided into three groups:
Glasses in which image processing and output is provided by a smartphone (Android, iPhone, Windows Phone). A modern smartphone is a high-performance device capable of independently processing three-dimensional images. Smartphone displays have a sufficiently high resolution. Almost every smartphone is equipped with sensors that allow to determine the position of the device in space.
- glasses, in which image processing is provided by an external device (PC, Xbox, PlayStation, etc.). The external device must be high-performance, and the glasses are equipped with position sensors.
- standalone virtual reality glasses (Lenovo Mirage Solo, with Google, Facebook’s Oculus Quest, Samsung Gear VR).
Helmets are a major component of fully immersive VR, as they not only provide surround images and stereo sound, but also partially isolate the user from the surrounding reality.
MotionParallax3D displays
Such displays use the inherent human mechanism of volume perception – motion parallax. For this purpose, at any given moment of time for the viewer, based on his position relative to the screen, the corresponding projection of a three-dimensional object is generated. Moving around the scene, the user can look at it from all sides, with all objects of the scene will move relative to each other.
The phenomenon of parallax greatly enhances the perception of volume. Unlike 3D cinema and 3D TV, which only use binocular vision, MotionParallax3D technology allows the user to view a 3D scene from all sides, as if all the objects were real. Moving the viewer relative to the screen, which disturbs the volume effect in 3D cinema, in the MotionParallax3D system only enhances the effect.
A system that uses a parallax mechanism must pick up the smallest movements of the user’s head and track them with high speed and accuracy, so the brain does not detect distortions of the geometry of objects caused by a delayed change in the image. The delay should be no more than 20 ms, for interactive games no more than 11 ms.
These devices provide, as a rule, incomplete immersion, because they are played on displays and do not isolate the user from the environment.