The Key to VR: Presence

Posted by Knar Bedian on Nov 8, 2016 10:43:43 AM

As you inch your way towards the ledge of the mountain your heart races and you start to experience a dizzying sense of vertigo. You’ve nearly forgotten that the thousand-foot drop that lies ahead doesn’t actually exist, and that your feet are firmly planted on a carpet. You are in a virtual reality simulation, but it feels very real.

The experience of believing the VR situation is not unique to you, however, many people report this, and for many VR designers this is the goal. This feeling of actually believing you are in a virtual world is called presence.

While there are other types of virtual experiences, including augmented reality (AR) and mixed reality (MR) which we’ve mapped out here, presence is most essential to VR, as VR aims to completely replace reality, rather than add to it.

VR and the power of presence have helped companies connect with clients and customers and improve product design. From travel to architecture to the automotive industry, VR has become both a production and marketing tool– be it Ford’s research and development using VR to determine the blind spots and adjust positioning of A pillars to improve visibility, or Marriott Hotel's “Travel Brilliantly” telephone-booth-like VR station lets users sample travel hotspots.

Creating compelling VR experiences is essential to the business case. If a user does not believe the experience, it will lack impact. Because of this, it is important to have a good technical understanding of what creates presence in order to apply good design thinking. Makers of VR systems typically highlight features that build visual presence; we’re going to focus on the five key elements that are most discussed in the world of VR:


Resolution
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Resolution is the number of pixels (individual points of color) contained on a display monitor, expressed in terms of the number of pixels on the horizontal axis and the number on the vertical axis. Perhaps the most obvious: the higher the resolution, the more realistic the image can be. There should be no visible pixel structure and stereoscopic distortion Full-feature VR systems should aim to have at 1,000 x 1,000 pixels per eye. 


Latency
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Latency is the amount of lag time between head movement and when the virtual picture adjusts. Latency was one of the major obstacles for early VR systems, as high latency (or too long of a delay in the shift in virtual perspective) can cause motion sickness.


Persistence

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Persistence refers to the state of the pixels: think of it as the
eye-tracking-based motion blur. Lower persistence contributes to more presence, or a more realistic experience. There are two main factors to consider for persistence: frame rate (measured in fps, or frames per second) and refresh rate (measured in hertz).

The frame rate is the number of still images shown every second. It’s like a flipbook-style animation: the faster the flip book is flipped, the more real and movie-like it will seem. Frames have to move at a certain rate in order to avoid motion sickness.

The refresh rate is the number of times the display screen image is completely reconstructed every second. A higher refresh rate helps avoid retinal blur and visible flickers. Full-feature VR systems typically require PCs or game consoles with advanced graphic cards that are capable of a refresh rate of 90+ hz (standard TV, and most video games, target only 30 updates per second).


Tracking
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VR systems should be capable of capturing the six degrees of freedom, which is a combination of two types of movement: rotation (tilting and turning of the head) and translation, or body movement through three-dimensional space (forward/backward, up/down, left/right).

Both mobile and full-feature VR systems track head rotation, but only some models of full-feature VR systems capable of tracking translation are called “room-scale,” and require a physical area for the user to move about. When users move around real space, their motion is reflected in the virtual world.


Field of View
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Field of view refers to the extent of observable environment. Usually, VR headsets aren’t truly 360º views, but a larger field of view will improve presence.

Full-feature VR headsets typically have at least 100 degree views (and often, wider) while mobile VR typically offer at most 96 degrees. Correcting for distortion also helps to improve field of view and presence.  


Beyond Visual Presence

While these five elements all work to establish presence in VR, a truly immersive experience requires a VR system to appeal to the other senses, too. To learn about other elements that contribute to a sense of presence and help a VR system “trick” users into thinking they exist in a virtual environment, take a look at our VR guide.

Have you had a VR experience that had exceptionally good or poor presence? Tell us about it in the comments below. Interested in working with us on a VR project? Let us know about your idea.

Topics: VR, Presence

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