Mixed reality headset
A mixed reality headset is a headset that overlays computer generated content on a coordinate system that has spatial registration to the real world. It typically uses camera passthrough and a halo headband.
It is often shortened to MR headset.
It employs the concept of mixed reality, which is largely the same as augmented reality, although in practice mixed reality tends to use camera passthrough instead of optical seethrough. Examples of passthrough gadgets are the Quest Pro and the Apple Vision Pro.
It has two main parts: The visor and the headband. The visor has the displays on it and sits in front of the eyes.
The difference between an MR headset and a VR headset with camera passthrough is that an MR headset leaves the user's periphery open, with the displays only taking up the visual field's useful working space.
Microsoft called the HoloLens a mixed reality headset.
MR headsets input head movement, which is taken in by a tracking system, fed to a CPU, then a scene is rendered according to the head position by a GPU, which is sent to a display system, which converts electrical signals to photons (light). Then the light optionally passes through optics and into the user's eyes.
Features[edit]
Field of View[edit]
MR HMDs benefit from displays with large field of view (FOV) that comprise the entirety of the user's vision. With both eyes, humans have about 180 degrees FOV when looking in front of them. The display of a VR gadget should cover as much of the vision range as possible. A large FOV is important to create immersion for the wearer.
Two-view imagery[edit]
A MR HMD has to display virtual objects in a 3D world. A two-view display shows each eye a different image of the same scene. The images are of the same scene viewed from slightly different angles. This process creates depth perception by mimicking how our eyes perceive the world in real life. It is called binocular disparity.
Rotational Tracking[edit]
A key feature of an HMD is the ability to track the wearer's head rotations. The images shown on the display change according to the wearer's head movements. Head-tracking is an essential aspect of the HMD that allows the user to become immersed and feel presence.
Rotational Tracking is achieved through sensors such as the Gyroscope, Accelerometer and Magnetometer within the HMD.
Positional Tracking[edit]
Positional Tracking is often performed with sensors and cameras external to the HMD. These peripherals can track the position of the user's head, body and hands anywhere within the range of the gadgets. They can not only track the rotational movements like the inboard sensors but also translational movements.
Construction[edit]
An MR headset can use a halo headband, like on the Quest Pro.
It is possible to build a halo headband style headset with a detachable visor. It is possible to build one that has headphones in the headband.