RE: [Algorithms] FPS Questions

[Tom F. <to...@mu...>]

...except that eye's don't have a "shutter" or a "framerate" - they have a
response time, but it's continuous, not discrete like a movie camera. So you
can't say that the eyes are "out of sync" - they don't _have_ a sync.

As for finding the optimum details settings to get "n"Hz on a machine, with
continuous LoD methods, you can get quite close (+/- 5Hz is not too hard to
achieve 95% of the time). You have some sensible defaults for rendering
quality (i.e. how many passes), according to card type, allow the user to
override them if they feel like it, and then CLOD up or down to get the
right frame rate (within sane limits).

Tom Forsyth - Muckyfoot bloke.
Whizzing and pasting and pooting through the day.

> -----Original Message-----
> From: Jim Offerman [mailto:j.o...@in...]
> Sent: 01 August 2000 15:58
> To: Algorithms List
> Subject: Re: [Algorithms] FPS Questions
> 
> 
> I gave my original query some more thought, and I think I have found a
> plausible explanation as to why 60 fps might be perceived as 
> being smoother
> than 30 fps.
> 
> The human eye in many ways works like a camera (note: 
> actually, it is the
> other way around): the retina is exposed to light for a small 
> period of time
> and then the accumulated light signal is transmitted to the 
> brain before the
> retina is exposed again.
> 
> Let's assume for a while that the eyes record at a steady 30 
> fps. If our
> game also runs at 30 fps, the eye sees one frame at the time. 
> However, if
> the game runs at 60 fps, the eye sees two frames at the time, 
> which are
> blurred together, resulting in a form of motion blur.
> 
> Another important aspect is that your eyes will _never_ be in 
> sync with the
> frame rate of your game, so it is possible that there exists 
> a moment where
> your eye records a frame, but there is nothing to record 
> (since the monitor
> is doing a vblank). This will certainly be perceived as a 
> discontinuity of
> the ongoing motion on the screen. The higher the framerate, 
> the less likely
> that such situations occur.
> 
> Finally, I must agree with the lower latency factor, since 
> while our eyes
> may be relatively slow, our responses (generally) are _really_ fast.
> Specially, if someone is trained in some response, then it becomes a
> reflex... An experienced FPS player might be using his brain 
> as little as
> 25% of the time, the rest of the time, his actions are merely 
> reflexes.
> Hence the phrase 'mindless killer' ;-).
> 
> > Why not just ask the player what they want and then scale 
> the engine to
> that
> > speed.  If they want 'liquidity' at high frame rates then 
> scale back and
> use
> > lower level of detail models.  If they can't tell the 
> difference then
> > they'll pull the frame rate down to 30fps and get better 
> looking visuals.
> 
> We usually achieve this by offering the player some controls 
> over detail.
> Though it might be nice if your engine includes a little util 
> which finds
> the optimum detail settings to get n fps on a given 
> machine... but I can
> tell you that _won't_ be very easy, so better put that on the 
> 'things to do
> when I have time left' list ;-).
> 
> Jim Offerman
> 
> Innovade
> - designing the designer