Types of HMD

Presently, there are two basic categories of HMDs for VR: desktop VR and mobile VR, although the distinctions are increasingly becoming blurred. Eventually, we might just talk about platforms as we do traditional computing, in terms of the operating system—for example, Windows, Android, and console VR. Let's look at each of these HMDs in more detail.

Desktop VR

With desktop VR (and console VR), yourheadsetis peripheral to a more powerful computer that processes the heavy graphics. The computer may be a Windows PC, Mac, Linux, or a game console, although Windows is by far the most prominent PC, and PlayStation is a bestseller intermsof console VR.

The headset is connected to the computer with physical wires (tethered connection) or a near-zero latency wireless connection. The game runs on the remote machine and the HMD is aperipheraldisplay device with a motion-sensing input. The termdesktopis an unfortunate misnomer since it's just as likely to be stationed in your living room or den.

TheOculus Rift(https://www.oculus.com/) is anexampleof a device where the goggles have anintegrateddisplay and sensors. The games run on a separate PC. Other desktop headsetsincludethe HTC VIVE, Sony'sPlayStation VR, andMicrosoft Mixed Reality.

Desktop VR devicesrelyon a desktop computer for CPU (general processor) and GPU (graphics processing unit) power, where more is better. Please refer to the recommended specificationrequirementsfor your specific device.

However, for the purpose of this book, we won't have any heavy rendering in our projects, and you can get by with the minimum system specifications.

Mobile VR

Mobile VR originated with Google Cardboard(https://vr.google.com/cardboard/), a simple housing device for two lenses and a slot for yourmobilephone. The phone'sdisplay shows twin stereoscopic views. It has rotational head tracking, but ithasno positional tracking. Cardboard also provides the user with the ability to click ortapits side to make selections in a game. The complexity of the imagery is limited because it uses your phone's processor for rendering the views on the phone display screen.

Google Daydream can be said to have progressed to the Samsung GearVR, requiring more performant minimum specifications in the Android phone, including greater processing power. GearVR's headsets include motion sensors to assist the phone device rather than relying on the phone's own sensors. These devices alsointroduceda three-degrees-of-freedom(DOF)hand controller that can be used as a laser pointer within VR experiences:

The next generation of mobile VR devices includes all-in-one headsets, such as Oculus Go, with embedded screens and processors, eliminating the need for a separate mobile phone. The Oculus Quest further adds depth sensors and spatial mapping processors to track the user's location in 3D space, 6DOF hand controllers, and in some cases even hand tracking without hand controllers.

The bottom line is that the projects in this book will explore features from the high end to the low end of the consumer VR device spectrum. But generally, our projects will not demand a lot of processing power, nor will they require high-end VR capability, so you can begin developing for VR on any of these types of devices,including Google Cardboard and an ordinary mobile phone.

Next, let's dive a little deeper into how this technology works.