On Oct 26, 06 20:52:10 -0400, Ed McCanless wrote:
I found this thread very interesting and helpful, since I am looking at video cards to upgrade my system. I am curious though, about the frame rates. Since movies look pretty good at 24 fps, and experts have claimed for many years that we can't see changes very much faster than that, what is the advantage of the extreme frame rates most of the newer cards offer?
Just trying to learn,
The following numbers of course vary a bit from person to person:
- The eye will see changing images as "moving" begining with 12fps
(if it is less, it will see them as several still images)
- Motion will *start* looking fluently with approx. 24fps
(Film is 24fps, NTSC Movie is 23.976fps, PAL Movie is 25fps)
- Even with 50fps judder will be eminent for sensible people
(IMAX is filmed at 50fps, I personally still think it is juddering)
- Images will start to look steady if shown 50 times per second
(PAL is 50Hz, NTSC 60Hz, for film each picture is shown three times,
so it is actually 72Hz with 24fps)
- Even with 75Hz flickering will be eminent for sensible people
(though AFAIK all agree that 100Hz is enough)
Strangely enough, this doesn't seem to apply to film (because I
haven't heard anybody complaining about cinemas with that respect,
which use only 72Hz)...
- The eye can detect motion with a frequency up to 200Hz. The brain also
anticipates changes in the environment at approx. that rate, and gets
distracted if the input from the eye doesn't follow its anticipation.
(in a virtual environment the perfect update rate would have to be
200fps, else you easily develop a headache. It goes without saying
that the typical update rates in these environments of less than 10fps
are way below this margin)
Additional:
- Old games had game logic and video rendering coupled, so in Quake you
could run faster if you had an video rendering rate of AFAIR 73fps.
- Old games had a lag of 3-4 frames, from input to final reaction on
screen. So if you had the game running at 100fps, your received update
time was closer to 25fps which is still slow for good reactions.
See also the last point of the top list (anticipated changes).
Hope this helps
Matthias
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Matthias Hopf