Computer Generated Virtual Reality (CG-VR) is the use of computer technology to create a simulated environment. Unlike traditional user interfaces, VR places the user inside of an experience. Instead of viewing a screen in front of them, users are immersed and able to interact with 3D worlds. The computer acts as the bridge to these artificial worlds by providing users with realistic and stimulating simulated experiences.
While there is no doubt that CG-VR is prevalent in the world of entertainment, it is also being frequently used as an educational tool in various fields.
In the educational realm, medicine is one of the biggest beneficiaries with the development of surgery simulation. This is often used as a training aid and enables the surgeon to perform an operation on a virtual patient or to see inside the human body. It is also used as a diagnostic tool in that it provides a more detailed view of the human body compared to X-rays and scans.
Another popular use of virtual reality is aviation. Flight simulators have been used to train pilots for more than 80 years. In that time, there have been many breakthroughs in aviation technology. Now, virtual reality is about to usher in a whole new era of professional pilot training, with far-reaching consequences for the aviation industry.
Most standard virtual reality systems use virtual reality headsets to generate realistic images, sounds and other sensations that simulate a user's physical presence in a virtual environment. However, as explained later, there are other types of virtual reality system that creates a realistic virtual environment using multiple projectors.
Virtual reality requires high refresh rate and resolution to be able to move smoothly and naturally within a virtual space. It is a core requirement not only for an enjoyable 3D experience itself, but also to prevent so-called “simulation sickness,” which might cause dizziness, headaches or even nausea.
Many high spec VR headsets have two low persistence OLED displays, one for each eye, with resolution of 1200×1080 pixels and a refresh rate of 90Hz. Low persistence allows for the display of an image for two milliseconds per frame. The combination of the high refresh rate and low persistence will prevent users from experiencing motion blurring or judder, which is usually experienced on a regular desktop monitor. As a result, the user experiences an almost tangible sense of the virtual environment and objects within it.
Try to think of each lens in the headset as a separate display. Since VR headsets use a dual-lens setup, with one lens (or display) dedicated to each eye, resolution must be considered as double (1200×1080 per display equaling 2160×1200), with a refresh rate of 90Hz.
Furthermore, the headsets also render an “eye buffer” of 1.4 times the size of the 2160×1200 resolution. This results in a true render resolution of 3024×1680, or 1512×1680 in each eye. The purpose of the eye buffer is to compensate for the distortion of the headset's lenses. With a rendering resolution of 3024×1680 at a 90Hz refresh rate, this creates a graphical demand of up to 457 million pixels per second. This means that by raw rendering requirements alone, a VR game or application will require approximately 3x the GPU power of a traditional 1080p application.
If a 1080p application demands this much GPU power, imagine when HD becomes obsolete and we migrate to 4K/8K applications!
To make the demands even more daunting, the headsets have to render two slightly different scenes per frame to ensure correct parallax and depth cues. So, it’s not quite as simple as looking at the raw pixel count combined between the two lenses. This is known as “stereo rendering” which increases both the CPU and GPU demand of rendering compared to rendering one image on a single flat screen.
The physiology behind VR sickness is not completely understood. Fortunately, research has uncovered some clear indications of certain conditions that cause VR sickness.
It seems that the images projected from virtual reality have a major impact on sickness. The refresh rate of on-screen images is often not high enough when VR sickness occurs. Because the refresh rate is slower than what our eyes process, it causes a discord between the processing rate and the refresh rate, which causes the user to perceive glitches on the screen. When these two components do not match up, it can cause the user to experience motion sickness.
The resolution of graphics can also cause users to experience this phenomenon. When graphics are poor, it causes another type of discord between what is expected and what is actually happening on the screen. When on-screen graphics do not keep the pace with the users' head movements, it can trigger a form of motion sickness.
Another type of virtual reality is a Cave Automatic Virtual Environment (CAVE). CAVE is an immersive virtual reality environment where projectors are directed to between three and six of the walls of a room-sized cube to generate a virtual space.
A lifelike visual display is created by projectors positioned outside the CAVE and controlled by physical movements from a user inside the CAVE. A motion capture system records the real time position of the user. Stereoscopic LCD shutter glasses convey a 3D image. The computers rapidly generate a pair of images, one for each of the user's eyes, based on the motion capture data. The glasses are synchronized with the projectors so that each eye only sees the correct image. Since the projectors are positioned outside the cube, mirrors are often used to reduce the distance required from the projectors to the screens.
Many people consider CAVE to be the most immersive display system for VR environments. The display gives the user a very wide field of view -- something that most head-mounted displays can't do. Users can also move around in a CAVE system without being tethered to a computer. Furthermore, projecting a high definition (4K/8K) image onto multiple projection walls helps to create a multisensory immersive environment that can emulate an endless range of scenery.
To set up CAVE, clusters of desktop PCs or a powerful graphics workstation is needed to generate high definition images projected on each screen, creating a cohesive virtual environment using multiple projectors.
(1) Dual Intel® Xeon® processors with up to 56 cores and 96 PCIe lanes to offer top of the line processing power to meet and exceed the demanding requirements for running VR applications. It also eliminates low GPU usage due to CPU bottleneck.
(2) A custom motherboard supporting up to 4 full-length, double-width PCIe x16 cards, allowing for the installation of up to 4 high-performance GPUs. Running multiple powerful GPUs will provide additional headroom for real-time rendering and higher graphical quality essential for demanding VR applications.
(3) Large-capacity main memory (max 6TB, 256GB DDR4-2666 card x 24). As VR supports higher resolution, large-capacity main memory is needed to handle large amounts of data and perform optimally to avoid frame dropouts or tearing that make people sick. Your graphics card, CPU, and RAM are all involved in the effort to create the geometry, textures, lighting, and effects that compose each frame.
(4) Supports up to 16 NVMe SSDs (max 256 TB, 16TB SSD x 16). An average amount of storage will suffice for HD VR but 4K VR requires much more space for data. Furthermore, the speed of your hard drive is crucial if you need to stock VR content and access them on the fly for real-time rendering to keep the VR experience seamless and completely immersive.
(5) A custom-designed motherboard utilizing a PCIe switch on the NVMe SSD side rather than the PCIe slot side to prevent slowdown in video transfer speed. This feature is crucial to a smooth and accelerated processing of heavy VR data.
Source: Virtual Reality Society, AVADirect, Logical Increments, Antycip, Wikipedia