The eyes retina consists out of 6 million photoreceptors that can sense red, green and blue wavelengths.
Furthermore there are over 100 million very sensitive photoreceptors that only perceive light and dark values.
The most important receptors that give us this very fine acuity we perceive sit in the central part of the retina,called Fovea. Almost all of the 6 million color photoreceptors sit here. This part of the eye
scans constantly our environment and lets our brain build up a very large FOV sharply perceived image although the fovea makes up only 5% of the FOV.
The rest of the retina mainly consists of receptors that perceive light and dark values and that play a especially important role for the night because this is the part of the day where most of the danger occur.
The night has only 1/1000-1/10.000 the brightness of a day and so these receptors are much more sensitive to photons than color receptors, thus we have so many of them.
So in principle, to simulate very sharp virtual images and it would't take more than 2 million RGB pixels
IF those pixels were all the time at the exact right location where the fovea is looking at but what does not happen because current displays for VR are very large and static and have not the required resolution.
Samsung announced that they are already working on 11k panels with a pixel density of 2250ppi that
they want to present at the olympic games in 2018 in Korea. Those pixels measure sth around 10x5µm.
This is not far from the actual size of photoreceptors itself which measure 2-3µm in diameter.
Also reseachers at the Fraunhofer Institut in Germany showed an OLED micro display with a pixel density of about 5,000ppi or 1 million RGB pixels at 0,38 inch. These pixels measure only 4,7µm and there is no pixel gap.
Since OLED panels can be produced only a few tens of microns(sub gramm) thick it would actually be possible to create a panel that would follow your eye view placed only 2 cm in front of it if there was a lens that you could put right in front of the panel or onto they eye itself in order to see a sharp image.
There is actually one company that has build such a device, a contact lens that you can put onto your eye and
solves the whole optics problem. innovega-inc.com (they are planning to release sunglasses that are going to incorporate a 1 inch microdisplay)
https://www.youtube.com/watch?v=aLCGBuT5vBQ
One cm² of this OLED device would only weigh 1mg ( that is the weight of one cm³ of air)
So how will VR devices evolve? Are we going to build panels with the size of 6 inches and a ppi of 5000ppi
although it would only require an inch or one half to simulate virtual worlds with perfect visual acuity?
From a cost POV the smaller version would be much better but it would require special optics and a very
reliable functioning eye following mechanism.
On the other hand Samsung is going to demonstrate that it will be possible to build 11-15k displays cheaply.
Anyways the gap between microdisplay ppi and smartphone ppi is closing and it will be very exciting to see
how fast electronic manufacturers will come up with a solution to the problem.
Micro OLED with densities of 5,000 to 10,000ppi in principle could also be build onto a contact lens since OLEDs are flexible, very thin and since very recently also 100% stretchable.
http://www.nature.com/ncomms/2015/15071 ... s8647.html
http://www.jst.go.jp/erato/someya/en/research_results/
From a rendering POV it would be completely insane to even think of rendering +8K resolutions.
So i think rendering speed isn't very much of a problem if VR is done right.
It will be interesting to see if this possible evolution is even going to happen in anyway since Magic Leap
is already promising the perfect VR/AR device with near perfect visual acuity AND rather than only projecting
stereoscopic images will be able to deliver true 3D in VR and AR.