Optimum viewing distances

[Grauniad]

With the advent of Retina and 4K displays, the old controversy of optimum screen size, viewing distance and pixel density rears it's head again. Here is an old, but good article containing some of the basic facts (arc-degrees), a calculator and a few links to calibration tools.

Carlton Bale.

Oh yea, Samsung will be announcing their 98-inch 4K TV at IFA in Germany this week. The only puzzling thing in this article is the reference to "vertical mounting" - How else would one mount a TV on a wall?

Edit:  9/10/2013/ Just found another very useful article on optimum display resolution (with some fancy-looking math). Are we at the limit of resolution improvements that people can notice?

[Kingo]

Well, they could place it on a shelf mounted on the wall :P
Of course, that isn't very stable...

[teknotiss]

The only puzzling thing in this article is the reference to "vertical mounting" - How else would one mount a TV on a wall?

perhaps a set of vertically oriented mounting rails so you can slide it up and down, rather than horizontally, since it's so large it might not fit onto a short wall easily.
other than that i have no idea.  ???