| pezus said: I actually stumbled on a really good article on this, which explains how our eyes work and discusses the 'supposed' FPS limit of ours: http://amo.net/NT/02-21-01FPS.html . It's really informative so I suggest you read it. |
This mentions the 1/220 sec flash test again
The USAF, in testing their pilots for visual response time, used a simple test to see if the pilots could distinguish small changes in light. In their experiment a picture of an aircraft was flashed on a screen in a dark room at 1/220th of a second. Pilots were consistently able to "see" the afterimage as well as identify the aircraft. This simple and specific situation not only proves the ability to percieve 1 image within 1/220 of a second, but the ability to interpret higher FPS.
A 30 fps camera will also pick up an image flashed like that. What would be interesting to know is at what rate can the human eye pick up differences in 2 subsequent frames. Show 2 frames 1/220 sec directly after eachother, can you see both or do you see the sum of the 2?
I suspect the latter, which is why fast moving objects still look bad at 60fps. You see a bit of frame 1 mixed with frame 2, you see the object in 2 places at once.
I do agree that adding motion blur to games is pointless. The human eye and brain track things that you are focussing on, compensating for the motion so you can see them clearly. Have you ever sat in a train staring out the window at the tracks speeding by? The faster you go the harder it gets to track the individual rungs until it all becomes a blur, yet every now and again your eyes still manage to catch on and give you a still frame.
Tracking fast moving objects doesn't work with fixed framerates on screens, they merely transition from 1 spot to the next. Adding motion blur doesn't help either. Sure it simulates how things look that you are not currently focussing on or are moving so fast you can't keep up with them, those will have blur in real life too. Giving everything that moves motion blur makes everything look blurry, making it impossible to see clearly that which you are trying to track.
Instead of motion blur, faster moving objects should be displayed at a higher framerate. This is how 120hz and 240hz tvs work, adding in between frames makes it easier to track the moving elements. Basically the distance an object travels between two frames should be constant for all moving elements. Unfortunately we're still stuck with fixed display refresh rates, and more importantly a cap of 60fps over HDMI. If we could send 240fps to the screen then it will be easier to start experimenting with variable frame rates for different elements. (Assuming hardware won't be prowerful enough for awhile to update the whole scene at 240 fps)
The human visual system is just as impressive a stabilizer system as its ability so focus quickly and track objects. Your eyes are constantly moving and scanning without you being aware of it conciously. Look at someone elses eyes and you'll be amazed at how much they jump about depending on what they look at. Yet they experience a perfectly stable mental image.
The mental image you experience is build from all the elements you track with your eyes to form one cohesive stable image. Parts you're not currently paying attention to are pretty much ignored / filled in automatically. Look up inattentional blindness to see what I mean. If games only knew what you were looking at, that could save a lot of rendering time. Actually a lot of games do know. But I guess it's not good for screenshots and you tube videos if game x is only showing high visual fidelity where you are aiming.
