human eye can see approx. 120 deg
https://en.wikipedia.org/wiki/Vision_span
and can move 120deg. so, human eye with fixed face can see 240deg.
also minimum pixel for human eye is approx 28sec.
https://webvision.med.utah.edu/book/part-viii-psychophysics-of-vision/visual-acuity/
Thus, for full experience for VR, we need approx 240deg * 60min/deg * ((60sec/min)/30sec) = 14400pixel.
Let's call "FullRetina resolution = (14K)^2".
