Uh I have a question about something that's been bugging me off and on over the years.
You know when you look at the replays or spectate and watch the cars go by? And when you look at the wheels you see the rims turning in the opposite direction of what the car is going? Is that an animation that's modeled in like in GTA(?) or is it a real illusion like what you see in real life?
I hope that makes sense...

I'll try to make it simple(Im sure throves will correct me)

When the spokes of the wheels are going slow you can clearly see which direction the wheel is turning, but as the speed increases you eyes 'sample frequencey' only catches parts of the revolution and at that magical point where the wheel rotation frequencey mis-matches your eyes frequencey it only 'appears to be turning backwards. The clearest and most noticable example of this could be seen if you stand in a flourescent lit room whilst looking at any piece of equipment that has a high rotational frequencey like a drill for example, which is why you will never or should never see un-defused flourescent lights in any workshop as it is illegal.

Yeah that is called Aliasing efect, just in the night (the lights make that), on the t.v., etc. No in the day without any frecuency exposur.

Quote from Jonas8431 :

Yeah that is called Aliasing efect, just in the night (the lights make that), on the t.v., etc. No in the day without any frecuency exposur.

Yeah when its seen on TV it's because the frequencey of the camera is mis-matched, and when at night is because the lights only let you see at the lights frequencey...im getting congused its late

Quote from CSU1 :

I'll try to make it simple(Im sure throves will correct me)

When the spokes of the wheels are going slow you can clearly see which direction the wheel is turning, but as the speed increases you eyes 'sample frequencey' only catches parts of the revolution and at that magical point where the wheel rotation frequencey mis-matches your eyes frequencey it only 'appears to be turning backwards. The clearest and most noticable example of this could be seen if you stand in a flourescent lit room whilst looking at any piece of equipment that has a high rotational frequencey like a drill for example, which is why you will never or should never see un-defused flourescent lights in any workshop as it is illegal.

So are you saying I really AM seeing an illusion, or are you saying that "illusion" is animated in the coding for realism?

In LFS, it's most likely not an illustion, I'm pretty sure the rotation is drawn, but due to either your framerate or refresh rate, you'd get the same illusion.

I'm guessing there's not some line of code that says "at x velocity, start spinning wheels backwards"

Some motion blurring would be nice so it looked proper.

What we still need is some sort of a blurred wheel texture in front of the spokes, which increases in opacity when the speed goes up. I think this would be the best way to implement it without having to ditch the 3D wheels.

And rotars that spin with the wheel, and glow when they get really hot. But, I'd take wheel blur first I spos'

Its a real byproduct of you FPS. The illusion is real and not an intentionaly modeled effect.

Quote from CSU1 :

(Im sure ... will correct me) ... your eyes frequencey

Your eyes don't really have a frequency per se... photoreceptor cells each have their own response rate, but we've got about 130 million of them so there is considerable overlap. Turns out that we only see this effect (as you suggested) when we're looking at something that is in fact flickering (such as street lamps).

Quote from Racer Y :

So are you saying I really AM seeing an illusion, or are you saying that "illusion" is animated in the coding for realism?

Yes, the illusion is animated in race sims as everything is running 'internally' at the same frequencey. So once again, when you see it in real life on TV the illusion is the cause of the TV camera's sample frequencey(or ever noticed a PC monitor in the b.ground on a TV show, thats because the recording camera's frequencey is mis-matched to the PC monitors) and when seen in games its is only animated aliaising.

@wark, yep I understand, just last night I was abit tired and confused at three am

I seen this effect today whils looking at a cars wheels go by look through a metal fence from a distance of about 20 - 30 feet, the alloys appeard to be going backwards because of the fence messing it all up

most things supplied with a single phase AC supply will have this stroboscopic effect due to the 50hz supply frequency I believe its referred to as the wagon wheel effect, its especially noticable under discharge lighting and can cause many problems in industry (rotating machinary).

Its the same as blinking 50 or 100 times each second, your eye misses some information when its closed, and if the rotation matches your rate of blink then the object (wheel) looks like its standing still. change rotation rate or rate of blink, and it will appear to start to move again .

I remember first seeing it in LFS and thinking it was cool

SD.