Check out this video http://xiph.org/video/vid2.shtml which was recently posted here. Also the wikipedia page on sawtooth waves has an animation showing additive synthesis of a sawtooth wave: http://en.wikipedia.org/wiki/Sawtooth_wave
And Quake. Holy shit. Playing that game at 144hz makes it feel incredibly real, even if its blocky and pixilated, the movements are incredibly organic and the camera turning feels like a head turning rather than spinning around on Google Maps.
It's my understanding that you just need 2x (two points in a sine wave) to construct a unique wave. If you're getting a sawtooth, it means that you're sampling a wave that is composed of very high frequencies, and you're accurately sampling it, so a DAC can reconstruct it uniquely.
So if you sample 2xMaxFreq you have samples that describe the full signal and can reconstruct it exactly. So if our eyes really are 100Hz we can't see anything above 50Hz. That seems to align well with the ~50/60Hz threshold for flicker free viewing. Apparently higher framerates are only useful for when we have fast movement across the field of view which would be the case for FPS:
https://en.wikipedia.org/wiki/Flicker_fusion_threshold#Visua...
>So if our eyes really are 100Hz we can't see anything above 50Hz.
I'm not sure this follows as we're not perceiving waveforms when light hits our eyes, but we're perceiving intensity of energy hitting our receptors.
If you make the constraint/assumption that during reconstruction that you rebuilding a time domain signal composed of series of sinusoidals, then you're in the clear at just 2x sampling. For example, in Figure 2 in the article, it states that 2x sampling only provides frequency information, and not amplitude and shape. This is true if we assume that we're trying to directly reconstruct -any- periodic signal. Then if we sample at only 2x of the signals fundemental frequency, we are in fact stuck.
This can cause certainly cause confusion. So I think the usual way (I just dinker with DSP for funsies and a little bit at work, so I might have got it mangled) to deal with this confusion is to remember that sawtooth and square (and whatever) signals are chocked full of high harmonics that also must be sampled at or beyond the nyquist limit for you to be able to construct it.
In the past this was achieved by setting your CRT to a low resolution and upping the refresh rate. More recently you can get TN LCD panels that offer 120 or 144hz update rates.
Moving the mouse in small quick circles on a 144hz screen compared to a 60hz screen is a very different experience. On a 60hz screen you can see distinct points in the circle where the cursor gets drawn. With 144hz you can still see the same effect if you go fast enough, but it is way smoother.
This makes a huge difference for being able to perceive fast paced movements in twitch style games and is the reason there has been a shift to these monitors across every competitive shooter.
My thoughts on this is that this behavior is similar to signal sampling theorems. Specifically the Nyquist theorem talks about how you have to sample at at least 2x the max frequency of a signal to accurately represent the frequency. For signal generation this means that you have to generate a signal at at least twice the rate of the max frequency you want to display. If you want to accurately reconstruct the shape of that signal you need 10x the max frequency (for example two samples in one period of a sine wave makes it look like a sawtooth wave, ten samples makes it look like a sine wave).
So, if you're moving your mouse cursor quickly on a screen or playing a game with fast paced model movement even if your eyes can only really sample at something like 50-100hz the ideal monitor frequency might be 1000hz. There's a lot of complexity throughout the system before we can get anything close to this (game engines being able to run at that high of a framerate, video interfaces with enough bandwidth to drive that high of a framerate, monitor technology being able to switch the crystals that fast, etc.).
Yes, 48fps movies typically look less cinematic, but I think this is a flaw in movie making technology and not of the framerate. The fight scenes in the hobbit sometimes look fake because you can start to tell how they aren't actually beating up the other person. This detail is lost at 24fps and is why they have been able to use these techniques.