[opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 6 Jul 2017 01:13:21 +0000
Craig Birkmaier wrote:
No, it becomes a question of economic interest. There are
significant costs related to supporting higher display resolutions;
Another déjà vu all over again. You made the same arguments with HDTV. For
instance, you said the same things about why HD news would never happen. And
yet, ...
So let's get beyond vague words. The only thing that matters is whether the
improvement is usable, and I'll address the specifics below. I've never seen
coherent and convincing discussions of this topic (not saying they don't exist,
but I've not seen any). I've come to conclude that the factors that matter most
are (a) the horizontal field of view (FOV) that is acceptable but not
excessive, and (b) the perceptibility of individual pixels **implied by that
viewing distance**.
The horizontal FOV matters because with movement on the screen, an excessive
field of view creates nausea. The ears don't sense the motion that the eyes
see. But keeping the field of view relatively small avoids this effect. What's
small enough? I've looked this up and have found this problem is very real in
gaming. It seems that games developed for consoles, where field of view is
typically a little greater than what it is when watching TV (say, at most in
the 40-50 degree range), create nausea when played on PCs, unless there's a FOV
adjustment available in the game.
In the articles I read, they claimed that FOV for games played on a PC is very
wide, like 60 degrees up to 100 degrees or so(!). And that (understandably) if
console games are played on a PC, that close to the screen, you get seasick.
My tentative rule of thumb is therefore, for TV material, FOV should probably
be less than 50 degrees, or maybe less than 45 degrees. With that in mind, NOW
you can determine whether or not the extra pixels are needed. Until this point,
you just cannot make any believable assertions on whether UHD is "needed." The
trig is straightforward.
The expected result is that FOV (horizontal FOV, which matters most) should
only be a function of viewing distance, expressed in screen heights, and aspect
ratio. Here's why:
Tangent of an angle = opposite side dimension (aka screen width) / adjacent
side dimension (aka viewing distance).
Therefore, angle = arctan(opposite / adjacent)
If sitting in the middle of screen width, a distance perpendicular to the
screen, the angle described above is to the left and to the right, from
mid-point of the screen. Therefore,
FOV = 2 * arctan(horizontal screen dimension/2 / viewing distance)
Now express those dimensions in terms of screen heights:
FOV = 2 * arctan((screen height * aspect ratio) / 2 / (screen height * n))
where n is the number of screen heights that equal viewing distance. Now you
simplify, cancelling out the screen height
FOV = 2 * arctan(aspect ratio / (2 * n))
Simple, and as we expected, the actual viewing distance in feet, and actual
size of the screen, don't matter.
*Now* you can play around with the numbers. What kind of FOV angles do various
n values create? And you see that if you are 1.9 screen heights for viewing
distance, then the FOV is 49.95 degrees. Assuming that <= 50 degrees of FOV is
a valid limit, to avoid seasickness in TV material, we can then see whether 4K
makes sense or not.
Using similar math to what I just described, the separation between pixels can
be calculated. At 1.9 screen heights of distance, and 2160 vertical pixels,
pixel separation is 0.84 arcmin. This is good. Same scenario, with 1080
vertical pixels, would create 1.68 arcmin of angular separation between pixels,
which is marginal. The rule of thumb here being that values greater than 1
arcmin and less than 2 arcmin are marginal. Values greater than 2 arcmin create
quite visible pixels.
That's it. The only psycho-visual question being, what max FOV is reasonable?
Is it really something on the order of <= 50 degrees? Less? More? If greater
FOV is usable, then that's even more reason why 4K, if not 8K, makes sense.
The TV is in a corner, next to a fireplace.
Well, let's not belabor the obvious. If you have your TV crammed into a corner,
you won't have room. But I very much doubt you can make the case that the
average home has no walls that are at least 10 feet wide! Remember, there's no
significant bulk away from the wall, with the rolled up screens I'm considering
here.
Yup. Which is why viewing distance for home displays has not
changed appreciably.
No, as you can see, that's not it. What matters is FOV. And while absolute
viewing DISTANCE might not have changed, FOV changed a lot. The previous limit,
with analog, had nothing to do with motion sickness. It had to do with ugly
grain, ghost, and general fuzziness you would perceive, closer up. In other
words, resolution. With HD, you could make use of a greater FOV, which is why
the HD screens are so much larger than analog screens. And FOV was still not
the limiting factor for seasickness. You'd see individual pixels before ever
getting seasick. Even with 1080p.
With UHD, I'm proposing that FOV is the limiting factor. You can now achieve
FOV angular values that might create motion sickness, with general purpose TV
or movie material. In my own case now, 42" screen at 9.5 feet viewing distance,
my FOV is merely 18.2 degrees. So, plenty of room for improvement, without
risking seasickness.
These are the considerations that I think make sense.
Bert
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Other related posts:
- » [opendtv] TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- John Shutt
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Mark Schubin
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Mark Schubin
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Mark Schubin
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Mike Tsinberg
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense? - Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Craig Birkmaier
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- cooleman
- » [opendtv] Re: TV Technology: 4K for Broadcast: Is it Worth the Expense?- Manfredi, Albert E