[opendtv] Re: Practical realities on screen aspect ratios
- From: Craig Birkmaier <brewmastercraig@xxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 12 Jul 2017 07:53:13 -0400
On Jul 11, 2017, at 10:48 PM, Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx>
wrote:
Back to square one? Last time around, just days ago, you seemed to understand
that video games designed for consoles create motion sickness if viewed up
close with PCs. Where the game intended for a FOV of maybe 50 degrees is
viewed in the range of as much as 100 degrees FOV.]
We're not talking about playing video games on screens 15-30 inches from the
viewer Bert. We are talking about TV and movies screens.
Why do you keep changing the subject to cover for the fact that you do not
understand what you are talking about?
All of that was already forgotten? Here's a most direct excerpt that makes
the point, Craig. Followed by two other links you should read, to understand
what the problem is.
https://www.howtogeek.com/241285/why-video-games-make-you-feel-sick-and-what-you-can-do-about-it/
TOTALLY IRRELEVANT, as I told you when you wrote this the first time. And for
the record there are millions of gamers who don't get sick.
People watch big screens all the time and do not get motion sickness.
A vague banality.
No. Reality Bert. They don't put motion sickness bags in the seats in
theaters...
The issue is FOV, and motion in the image. When a scene was filmed to be
viewed within a certain max FOV, and you attempt to view that scene on a
display with much greater FOV, that's when you get sick. Anyone who has ever
sat in the front row of a movie theater will most likely have experienced
this effect.
I've had to sit in the front rows of theaters, and did so intentionally several
times to experience the limited viewing distance and to determine if the raster
(pixels) could be seen at this distance.
Sorry, nobody got sick, and one of those movies was a Star Wars episode with
lot's of motion.
You continue to spew garbage and to try to misdirect by using video games as an
example.
So, to get beyond square 1 again:
1. The ratio of FOV, horizontal to vertical, is *not* the same as the aspect
ratio of a screen, as Craig assumes. The larger the FOV, the more the
difference.
DUH.
But the last sentence is incorrect and meaningless.
For example, if you want to create relatively narrow FOV of 20 deg horizontal
and 10 deg vertical, the screen aspect ratio is 2.02:1. Almost the same as
the FOV ratio. But if you want to create FOV of, say, 120 horizontal and 60
vertical, the *FOV ratio* is still 2:1, but the screen aspect ratio has to be
3:1. ]
This is unbelievable - how do you come up with this crap?
The screen aspect ratio does not change. It just gets larger.
That's why we like wide screens better than square ones. The wider the
horizontal FOV, the more extreme becomes the screen's aspect ratio. Or, of
course, you can sit the viewer at the center and create a semicircular screen
around him.
This is completely wrong.
IMAX covers the entire human FOV. The screen is 1.4:1
2. With the possibility of much wider screens offered by OLED, with minimal
bulk, the issue of motion sickness will emerge. Sitting at, say, 1.5 screen
heights, with a 16:9 screen, creates a horizontal FOV of 61.1 degrees. Your
average TV or movie material, viewed that close, would very likely cause
motion sickness for the majority of viewers. The size of the screen doesn't
matter. What matters is the FOV, aka how far you are in picture heights, from
the screen.
This information is simply wrong.
Again, please provide a link to a reputable source about the motion sickness
issue.
Just for fun yesterday, I sat at the "designed viewing distance" of three
picture heights from our HDTV. Motion was not an issue - but the compression
artifacts were highly visible. One other minor detail - at that distance only
two people can sit in front of the screen.
I've experienced 4K and 8K at 1-2 picture heights - no problem with motion.
What changes is that you MUST use directed eye movement to search within the
image, just as we do in the real world - You cannot see the entire screen as a
single sharp image - the visual system does not work that way as I explained
yesterday.
This link has a diagram and description of theater design specifications that
provides the exact information we are discussing - i.e. The H & V field of view
at various viewing distances measured in picture heights. This is for a very
wide screen 2.39:1.
http://www.acousticfrontiers.com/2013314viewing-angles/
Note that the ideal viewing distance is about 3 picture heights, with the
screen covering about a 45 degree field of view.
Visual search - directed eye movement - is essential when you cover more than
30 degrees of the field of view - only a small portion of the screen covers the
fovea, the rest is covering the low resolution rods outside the fovea. The ART
of film making relies on the ability of the director and cinematographer to
focus your attention on what THEY want you to watch...then the axe wielding
attacker lurking in the shadows lunges at the victim you are watching.
In any event, viewing at 2 screen heights of distance, which is probably a
safer bet to avoid motion sickness, still benefits from more than just HD
resolution.
We view computer displays at 2 picture heights or less all the time.
And yes you need more resolution, which is why we have seen the typical
resolution grow from 72 DPI to more than 200 DPI.
This was also clearly indicated in the diagram and text of the Task Force
report that I posted.
The fact that you continue to ignore is that viewers DO NOT want to sit this
close to a screen; even a high end theater is optimized for 3 picture heights.
In the home the situation is "worse." You must deal with furniture placement
and the reality that you cannot get a group of people that close to the screen.
This is the reason that the typical viewing distance in homes is 9-10 feet.
Full circle.
Yup
You just keep spinning out of control...
Regards
Craig
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