VR technology roadmap
Common complaints against VR (Virtual Reality) were on the motion sickness caused by:
(1) the screen door effect (SDE) (visible gaps between pixels);
(2) mura (colour inconsistency of each pixel);
(3) aliasing (series of square blocks instead of curved lines);
(4) latency (low chipset processing and transmission speed); and
(5) the weight of headsets.
To mitigate these issues, headset makers are advancing the chipset, optics, display, and tracking solution to improve the user experience.
Chipset: Qualcomm XR series
Qualcomm launched its XR platform Snapdragon Extend Reality (XR) series in 2018 as its first SoC for AR/VR devices. The XR2 5G platform was announced in Dec2019, which is a derivative of the Snapdragon 865 (7nm). Oculus Quest 2 was the first to deploy the chipset, with a process speed doubling that of Snapdragon 835 in Quest 1. The XR2 enables 2x more video bandwidth, 6x higher resolution, and 11x AI improvement.
The strong performance has attracted most of the major headsets makers including HTC, PICO, DPVR, Lenovo, and Microsoft Hololens.
Display: Fast-LCD is becoming mainstream
The display in the HMD (head-mounted device) for VR is usually one or two pieces of LCD (liquid crystal display) or OLED (organic light-emitting diode) panel, depending on the design of the device, although a dual display system is preferred as human beings have two eyes. Although LCD and OLED are both applicable for VR displays, the majority of recently announced VR models have adopted LCD due to its cost advantage. OLED display was first used on VR devices by Sony’s PSVR, Oculus Rift, and HTC Vive due to its fast response time, which reduces motion image blur significantly.
However, OLED is limited by its inadequate lifetime and higher cost/lower yield for higher resolution. Normal LCD has the characteristic of high resolution, high brightness, long lifetime and low cost, but its response time is ~100x slower than that of OLED. As a result, LCD usually displays much more severe image blurs than OLED.
Optics: Fresnel lenses to replace aspherical lenses
Fresnel lenses are advocated by more VR makers due to their lighter weight and thinner centre. HTC was the first to use Fresnel lenses in its high-end product, Vive, followed by Oculus. To reduce the weight of VR devices and enhance the user experience, Fresnel lenses are more likely to be adopted by the majority.
Tracking solution: 6DoF and inside-out tracking solution will be the basic feature
6 degrees of freedom (6DoF) is an upgrade of 3DoF which adds rotational axes for rolling, yawing and pitching. 3DoF is enough for basic applications such as VR movies, but for a complete immersive experience 0like gaming, healthcare and training, 6DoF is required.
Most of the newly released VR headsets in 2021 employed 6DoF, and we expect the 6DoF function to be a basic feature for VR in the future.
In inside-out positional tracking, the camera or sensors are located on the headset being tracked (e.g. Oculus); while sensors in the outside-in scenario are placed in a stationary location (e.g. PSVR). We believe inside-out will be used for most VR devices for its mobility and flexibility, whilst outside-in will likely be used in specific scenarios such as healthcare VR and console-powered VR for its accuracy.