“So, we’re clearly thinking about augmented reality, virtual reality and things along those lines.” Woody Floyd, managing director of the Seattle office of Vectorform,
Will Virtual Reality be someday as “real” as reality?
Yes. I get asked this question so often. At events, conferences, online on forums, websites etc. It’s one of my favorite to ponder and contemplate on.
Kynan Eng – CEO at iniLabs neuroscience of VR and applications to rehabilitation.
A future VR device with output visually indistinguishable from reality would feature:
- 80 Mpixels per eye
- Full human eye field of view: 170° horizontal x 130° vertical
- 60x the current most powerful available consumer graphics card (Nvidia GTX 1080) for rendering synthetic game environments at 120 Hz – if you don’t render humans. If you want to render humans, increase that graphics power by a factor of at least 10.
(Calculations below current as of August 2016)
For comparison, one 8K display is about 35 megapixels.
Resolution & Field of View
For someone with 20/20 vision, the resolving power of their eyes is defined as 1 minute of arc, i.e. 1/60 degree. This means that for the pixels to be barely visible, a 360° display needs at least 360 * 60 = 21600 pixels of horizontal resolution.
The number of pixels actually needed in a VR display depends on the field of view. For example, theis about 100° horizontal and 110° vertical. This means that for each eye it would need a display resolution of 21600 * 100/360 = 6000 pixels horizontal, and 6600 pixels vertical. This is about 40 megapixels of resolution.
The field of view of oneis approximately 170° horizontal and 130° vertical. (We have a higher overall field of view due to partial overlap of our left and right visual fields – the stereoscopic vision area.) At full resolution, this works out to 10200 x 7800 pixels, or just under 80 MP for each eye.
The story is actually more complicated than the above calculations, for at least the following reasons:
- Human acuity is non-uniform: the fovea has maximum resolution, while resolution drops off towards the periphery. So if you can track where the eye is looking fast enough, you don’t need to render all pixels at maximum detail.
- Various visual acuity experiments have shown that the brain can do super-resolution in a training paradigm, i.e. results better than what is predicted by 20/20 vision. However, these cases are fairlyartificial.
Graphics Rendering Hardware
The current most powerful consumer graphics card is the Nvidia GTX 1080. It can run several modern graphics-intensive games such as Far Cry Primal at 4K resolution at around 40 Hz. We will take the visual realism of these games as our current benchmark for reality – which is reasonably true for fairly static scenes if you ignore humans or other complex dynamic objects such as deformable fabric.
For our headset, we need 120 Hz over two eyes, as 120 Hz is the benchmark for VR. This means we will need a theoretical graphics card with 15x the power of the GTX 1080 – per eye – to hit the required performance for a display with the field of view of the HTC Vive. For a full-human-FOV display, this number increases to 30x GTX 1080 per eye.