Understanding the different types of AR devices

Although the term Augmented reality is relatively new, early developments in the technology can be traced as far as 1900s. Howard Grub, an Irish telescope maker patented a device called the collimating reflector. It’s main purpose was to enable greater accuracy when shooting firearms by augmenting the crosshair view exactly at the user’s target vision. It tried to solve a pertinent challenge of the human eye of being able to focus only at one object at a time. Grubb’s invention inspired the development of a number of military gun sights.

Augmented reality devices can be broadly categorized into four types

Head up displays (HUD)

As the onboard controllers on flights became more complex, the information processing tasks for pilots increased with added number of sensors, avionics and flight controls. It is important for pilots to focus on what is happening outside rather than looking at the array of information inside the cockpit. Heads up displays were mainly invented for mission critical applications like flight controllers and weapons system dashboards. Critical information is projected on transparent screens mounted in front of the pilot. This enables pilots to look forward outside rather than looking down inside the cockpit. Like Grub’s collimating reflector, HUDs tried to solve the problem of shifting focus by using a type of collimating projector. The information projected is collimated (parallel light rays) focused on infinity so that the pilot’s eyes do not need to refocus to view outside the cockpit.

A regular HUD contains three main components; a projector unit, a viewing glass (combiner) and a computer (symbol generator). HUDs help increase situational awareness by reducing the shift of focus for pilots. Increasingly heads up displays have been finding ways into new automobile designs.

Helmet mounted displays

The next logical step for heads up displays was to move from the windshield to the helmet. Increasingly helmet mounted displays which use the same underlying principles of heads up displays are being used in aviation and other industries.

Holographic displays

Popularized in the Star wars series, Minority report and the Iron man series in the recent times, these type of displays use light diffraction to generate three dimensional forms of objects in real space. The fact that holographic displays do not require users to wear any gear to view them is one of their greatest advantages. These type of displays have always been in the realm of science fiction and have recently started gaining traction with products like Looking Glass and Holovect.

Smart glasses

As the technology transitioned from critical applications in defense and aviation to commercially available products, smart glasses have become one of the more popular types of augmented reality devices. Like their name suggests, these are glasses that augment your vision. Smart glasses are of two types:

Optical see through
In Optical see through glasses, the user views reality directly through optical elements such as holographic wave guides and other systems that enable graphical overlay on the real world. Microsoft’s Hololens, Magic Leap One and the Google Glass are recent examples of optical see through smart glasses.

Video see through
With these type of smart glasses, the user views reality that is first captured by one or two cameras mounted on the display. These camera views are then combined with computer generated imagery for the user to see. The HTC Vive VR headset has an inbuilt camera which is often used for creating AR experiences on the device.

Handheld AR

Although handheld AR is a type of video see through, it deserves special mention. The rise of handheld AR is the tipping point for the technology being truly pervasive. Augmented reality libraries like ARKit, ARCore, MRKit, have enabled sophisticated computer vision algorithms to be available for anyone to use. In handheld or mobile AR, all you need is a smartphone to have access to a host of AR experiences.

A brief note on VR

Virtual Reality could be awarded the prize for the most popular oxymoron. It provides the user an immersive experience within a 3D computer generated model or simulation. VR is generally accomplished with the use of head mounted displays (HMDs) or full immersive projection based systems. Google’s introduction of the smartphone based VR experience using cardboard, biconvex plastic lenses, and few other cheap components was a game changer. Anyone with 15$ and a smartphone had access to VR experiences earlier reserved for tech elites in industry and academia. It has been regarded as one of the most intelligent and high-impact moves that enabled a wider adoption and awareness of the technology.

Despite the hype around Virtual reality, it is almost certain that Augmented reality will be the more widely adopted one. Like the smartphone, it makes technology a part of the daily life of users without obstructing reality.

References:
1. Augmented Human — Helen Papagiannis
2. Practical Augmented Reality — Steve Aukstakalnis

Related articles:
1. Human eye’s understanding of space for Augmented Reality
2. A machine and human’s perception of the world in Augmented Reality
3. Fundamentals of display technologies for Augmented and Virtual Reality
4. Types of AR device
5. Building blocks for Augmented Vision
6. The Future of our Augmented Worlds
7. A computer’s understanding of space for Augmented Reality

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