Virtual Reality -How Does It Work?

What is Virtual Reality?

Virtual reality (VR) is a term used to describe three-dimensional computer-generated environments that replace the normal reality that humans are used to.

http://www.virtualrealitytimes.com/wp-content/uploads/2016/11/Virtual-Reality.png

Virtual Reality is experienced as 3D graphics, images, or 360-degree videos on computers or smartphones running mobile apps. The more expensive VR systems use wraparound computer displays or entire rooms with high-resolution displays integrated into the walls.

The VR environments are experienced through VR headsets, or goggles through headsets, like the Oculus VR system and the HTC Vive. Alternatively, a headset adaptor and mobile app software can turn a smartphone into a 3D display, like Samsung’s Gear VR system.

Major VR headsets not including the Vive

In addition to VR, many companies are now working to develop technology for so-called augmented or mixed reality, which blends the view of the real world with computer-generated graphics. The most familiar examples of AR gear are wearable see-through displays, commonly called smart glasses eg : Google Glass which I doubt people still use since google ended its development.

VR environments are often “immersive” mainly due to the fact that they engage a user’s vision, in some instances touch; to provide a seemingly three-dimensional simulated world to interact with and explore.

Many people have already experienced virtual reality games, and VR is of growing importance for training and education in fields like medicine, engineering, and the sciences. The world’s leading technology companies: Microsoft, Sony, Google, Facebook, HTC, Apple, and Samsung — are spending heavily to develop VR equipment and applications. Chipotle uses VR for training on how to quickly make a burrito to manage service wait times. KFC is planning to start using VR to teach employees how to make the perfect fried chicken the “Hard Way”, UPS uses it to train student drivers and Walmart to train new employees on different scenarios that happen in the store etc.

Ref: source

The ultimate essence of virtual reality is simulating the vision. Two autofocus lenses are generally placed between the screen and the eyes that adjust based on individual eye movement and positioning. The visuals on the screen are rendered either by using a mobile phone or HDMI cable connected to a PC

VR headsets track your head movements and adjust what you see depending on where you look thus virtual world appears to exist in all directions. Many VR systems let you control this virtual environment with hand controllers or gloves, including so-called “haptic” models that vibrate to provide a sort of virtual touch.

You can’t count on accurate position tracking with mobile headsets. Most use three-degrees-of-freedom (3DOF) motion tracking, which means they can follow the direction you’re facing very accurately, but can’t tell if you’re moving forward, backward, up, down, left, or right. To accurately track your position, you need a headset with six-degrees-of-freedom (6DOF) motion tracking. All tethered headsets have this thanks to either external sensors or outward-facing cameras.

To create a truly immersive virtual reality there are certain prerequisites — a frame rate of minimum 60fps, an equally competent refresh rate and minimum 100-degree field of view (FOV) (though 180 degrees is ideal). The frame rate is the rate at which the GPU can process the images per second, screen refresh rate is the pace of the display to render images, and FOV is the extent to which the display can support eye and head movement.

With reference to many headsets available today, HTC Vive and Oculus Rift both have 110-degree FOVs, Google Cardboard has 90, the GearVR has 96 and the new Google Daydream offers up to 120 degrees. As for frame rate, both HTC Vive and Oculus Rift come with 90hz displays, while the PlayStation VR offers a 60hz display.

If the GPU’s fps is more than the screen refresh rate then the image can become distorted. To counter this issue, the framerate is limited to the monitor’s refresh rate which is done using a tech called Vertical Sync (VSync). This prevents tearing (cybersickness) resulting due to the inconsistency between the frame rate and refresh rate.

how does it create a truly convincing feel of 3D?

Stereo Imaging’ is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. Stereoscopic methods present two offset images separately to the left and right eye of the viewer.

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Our eyes give us a feeling of depth perception out in the real world because they’re a couple of inches apart. As a result, they both have a slightly different view from one another. Our brains process those slight differences as clues about distance which gives our brains the perception of 3D; and in VR — eliminates any interaction with the real world

Virtual reality works by creating not one but two images in the headset — one for each eye, it’s like having two cameras views on the screen. It takes a fairly good GPU to do VR — the entire environment is being rendered around the player’s screen twice, as opposed to only having to do it once.

Passau Source : https://spdbv.vital-it.ch/TheMolecularLevel/0Help/StereoView.html

Other Elements That Go Into Creating An Immersive VR Experience

· Eye and Head Tracking:

Eye and head tracking can be ensured using laser pointers, led lights or mobile sensors. In mobile, we use the accelerometer to detect three-dimensional movement, gyroscope for angular movement and magnetometer to identify the position relative to the Earth.

Motion tracking Technology : http://www.onlinecmag.com/wp-content/uploads/2016/11/six-degrees-of-freedom.jpg?x43184

Gyroscopes are used to measure the angular position of your head (looking up/down/left/right) Accelerators are used to sense the speed of movement by measuring the force of acceleration applied to the headset.

3 Degrees of Freedom vs 6 Degrees of Freedom in Positional Tracking

The movement of the headset is tracked using sensors so that you can move and orient yourself in the virtual space, and you usually have 2 controllers tracked with the same technology.

The motion tracking is done with the phone’s gyroscope, and is equivalent to placing the needle of a compass in a sphere. They both move in 3 dimensions but in a gyroscope, it is not fixated on facing North because our phones can sense magnetism (how the compass works), the “click” gives off a magnetic signal which the app running the VR registers.

· The Impact of Sound:

Sound effects, are synced with the visuals, which create very engaging effects. By using headphones and 3D sound effects the user is completely immersed in the virtual environment.