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eeyore

Performance (Frame Rates) and Anatomical Biology

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Having come back to FSX (after earlier giving up on it until I had a decent machine on which to

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After many years of simming I have actually stopped looking at the FPS counter once I moved to FSX and a solid hardware platform. I remember spending so many days trying to increase the FPS number. After a constant tug of war battle with FSX I finally realized something. One day I decided not to enable the FPS counter and it was the best thing I ever did. The FPS number is not what is really important. It is the smoothness in between frames that makes the real difference, at least for me. I currently fly FSX with a lot of settings maxed out. It looks absolutely fantastic and very smooth. There are times when I lose a lil smoothness in heavy scenic areas such as NYC but you know something it is still very very flyable and enjoyable. Sometimes when Im flying and enjoying the amazing scenery and smoothness I may turn on the FPS counter to see the numbers and you would be surprised because sometimes those numbers can be anywhere between 9-15 FPS. Some time ago I would have thought oh man that is absolutely awful! I would then spend countless hours tryin to raise that magic number. I now realize that the FPS is only a small part of the overall picture. With the right hardware I think many people can fully enjoy FSX as long as they don't focus entirely on the FPS. Look at the smoothness instead I say. Just my 2 cents :)

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Not to rain on the parade, but there's a lot more to it than bragging rights, though that certainly exists here, as it does in every area of computing, and life. ;)25 FPS is fine for GA or Airliner flying, where the aircraft in question are stable by design. 25 FPS though is just simply insufficient for any kind of flying that requires very rapid and minute control inputs and responses, such as flying helos, aerobatic aircraft, close formation flying, and anything that moves at over 500 kts really.As for 25 FPS (actually 24) being the point at which the human eye can no longer detect differences in fluidity, it's unfortunately a total myth. That 'magic' number came from the film industry in its early days. At the time that standard was set (which we're oddly still using) they weren't looking for the rate at which differences in fluidity could be determined, but rather the *minimum* framerate at which movement could be considered fluid by the majority of people at all. This was simply due to the fact that back then film was a very expensive commodity.Anyway, whatever FPS floats your boat is great, but as I'm firmly in the aerobatic/helo/fighter camp I'll be satisfied with 60, if I ever get there, nothing less. :) 120 would be nice. I'd have to dig out my old CRT hehe.-mike

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I only *fly* the default airliners, with 3rd party paints, out of major airports. My FPS are, most often, well over 25, but the in/out popping and snapping of terrain textures and autogen is what ruins the experience for me. Too, Terrain textures don't fully focus until directly under the ac. Big turn off!!I have a Q6600 quad @ 3.6, and a Nvidia 8800 Ultra with 4 Gb ram on XP.Bruce

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There is another aspect to this subject. The motion of an observed object per frame. Take off on a moonlight night and head directly toward the moon. Whether your PC is going at 1FPS or 200FPS you will see no observable difference in the moon because its relative change per frame is zip. Now go and park you aircraft at a runway holding point and observe a jet landing. When the observed aircraft is directly in front of you its movement per unit time will be very rapid and I can assure you that at 35FPS(I run around at that rate)the movement of the observed aircraft will be large per frame and will not appear fluid. So the 25FPS might be OK for typical film sets where cameras can pan and reduce apparent movement between frames but flightsim is not a movie or TV studio set. Top competitive FPS players claim they can tell the difference between 70FPS and 90FPS. This is not a simple topic, claiming that 25FPS is enough is observably wrong in some circumstances. My experience is that 25FPS is OK if you are doing an approach to a runway where subject changes per frame are relativley small provided you are in an aircraft which has a relatively low approach speed. However, I have found that if flyig an aircraft with a 150Knot approach speed then 25FPS is not good enough for aircraft control purposes.

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Now you guys are fully on my turf, so I get to do a lot of explaining, a la any given James Bond villain.Film speed is closely related to the motors used to drive film through a camera and a projector. Before motors were used, film crankage was done by hand. Since film stock is expensive, many directors chose to undercrank the camera, so that it was common to see films in the 8-12 fps range. Once the process became automated, we saw projection move to around 24 frames per second (fps). This was largely due to the nature of AC current. You need AC to drive a rotary electrical motor. By timing the revolutions of the motor to the current, you get the the most efficient and smoothest drive possible. AC is different in Europe than it is in North America, which is why their film standard is 25fps and ours is 24. Film is largely irrelevant to the televised video culture (and I can got at length in very personal detail as to why this is so, but that's a different topic). Video analog signals are transmitted electrically, rather than optically. The most stable signal signal was 30 fps, which could transmit black and white images as well as sound. Again, the number is related to the transmitter (think of transmitting in multiples of MHz), rather than to any specific vagaries of human biology. When colour television was invented, the signal frequency was not aligned to travel at 30fps and provide sync audio and still be stable. So the NTSC standard comes to take away .03 of a single frame in one second. That three-one hundredths of a frame is used to encode the information television sets need for colour. The system is called 29.97 "drop-frame". The bear of it is, if you record synchronized audio at 30 fps, every second that goes by you will go out of sync by .03 seconds. Then there's PAL and SECAM which do the same thing as NTSC, but use different incompatible formats. Television is largely irrelevant to computer video culture. Since the computer renders video digitally, rather than in analog, you can freely jump between frame rates as you see fit. We are used to (nearly) 30fps, so that's kind of a benchmark of computer video. In reality, most game publishers shoot for 60fps. 60 = 2 x 30. The vast majority of people cannot see above 30fps, but that's not to say it's impossible. So why the extra unseen 30fps? It's called "overhead", and it provides a buffer of visual processing in case the game goes into a highly-detailed area. That way, the frame rate can bounce around freely between 30 and 60 fps, and the gamer won't likely see any difference. Putting on a frame rate lock can add so much stress to a processor that you will automatically slow the frame rates below optimum levels, so in many cases, if you can avoid locking frames, you do so. As to seeing above 30fps... some people claim its possible, and I do not doubt it. You can train yourself to perceive frames clearly. Some of my background is in classical animation, so I can tell you with 99%-100% certainty what your frame rate is from 1-24 fps just by looking. I can estimate 25-30 fps frame rates maybe 75% of the time. Anything above that, is just a guess for me. People who do pure video animation are usually better at estimating 30fps than me. Then there are gamers. Some of them are awfully good guessers at above 30fps. Are you one of them? One way you can tell is by fooling around with the refresh rate of your monitor. CAUTION: DO NOT SET YOUR MONITOR TO ANY RATE IT WAS NOT DESIGNED TO DISPLAY!!! If you set the monitor to a multiple of 30, then you might see some artifacts, blurring, or just get headaches. This is especially true of interlaced displays, I don't know so much about progressive scan. On an interlaced display set to 60 Hz, you will see "half" of a frame (called a "field") displayed alternately with the other "half" 30 times a second. These numbers ought to look very familiar. 30 fields a second is kind of like 30 fps. 30 fields times 2 = 60 cycles a second, which is what you see visually on a 60 Hz interlaced display.Another way you can tell if you are sensitive to frame rates above 30 is to spend time under fluorescent lights. Unlike incandescent bulbs with tungsten filaments, fluorescent lights strobe. They tend to do so past our perception, at around 120 - 180 Hz. But, we are back to those multiples of 30 again. If you are tuned to perceiving frames at 30 fps, then living under fluorescent lights will give you headaches and make you tired. It's not like Ned Flanders says, "They hum like angels! You're never lonely if you've got a fluorescent light!" It's more like a reason to take a blunt instrument to an otherwise innocent lighting fixture at five in the morning. MORE CAUTION: NEVER BREAK OPEN A FLUORESCENT LIGHT!!! IT'S FILLED WITH POISON!!! ALWAYS DISPOSE OF FLUORESCENT LIGHTS BY TAKING THEM TO AN APPROVED DISPOSAL FACILITY!!!So, anyways, I hope that helps. It seems every year someone comes up with this topic, and I always think it quaint to discuss it in the FSX forum because there are places in the FSX world you are never going to get 30 fps with the sliders on full. Jeff ShylukAssistant Managing EditorSenior Staff ReviewerAVSIM

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>This is not a simple topic, claiming that 25FPS is enough is>observably wrong in some circumstances. A respectful correction:Claiming that 25FPS is unnoticable is wrong in some circumstances. There are some who might feel that 25 is enough to be satisfied, even if it incurs some chop. :) Furthering on what Mike/Haldir/Lotus said above, the 24FPS in use by the movies has another major benefit which a computer screen has yet to bring (en masse) - and that is film/motion blur.When you take a photograph of something moving, especially moving fast, that object will often times be blurred because it is moving too quickly for the camera to take a sharp picture of it. Our brains take that blurry image, and combined with the frames before and after it, decode it into what appears to be relatively smooth motion. Our COMPUTER screens display one absolutely crisp image after another. There is no motion blur in the images, and this can be a jarring effect, especially at lower frame rates. Back in the day, 3DFX had a series of Voodoo cards who's big claim to fame was the fact they could do motion blurring, but they came out at the end of 3DFX's pioneering reign at the top of the video acceleration market, and were never widely adopted. To be honest, I'm a little surprised that the eye doctor indicated that 25 was the highest discernible rate... Oh well,-Greg

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>Claiming that 25FPS is unnoticable is wrong in some>circumstances. There are some who might feel that 25 is enough>to be satisfied, even if it incurs some chop. :) >When you take a photograph of something moving, especially>moving fast, that object will often times be blurred because>it is moving too quickly for the camera to take a sharp>picture of it. Our brains take that blurry image, and combined>with the frames before and after it, decode it into what>appears to be relatively smooth motion. You are absolutely right!This is the CRUCIAL difference: too many times over the years I've been reading this on too many forums to be able to count them...There's always someone starting the theory that, since TV and Motion Pictures use only 24 or 25 fps, this is the maximum the human eye needs to get a smooth motion.This might be correct IF computer generated images were "shoot" just like video/film frames. Unfortunately, they aren't. In video/film, there's a finite SHUTTER time, which adds the natural motion blur over moving objects (and the the camera movement as well), that our brain uses to AUGMENT the sense of smooth motion.If the shutter speed on a video camera goes too high, like at 1/1000th of a second, the result would be a noticeable jerky motion. But of course, putting the video in pause would look great, becuase you might be able to capture, for example, a fast moving race car which would have been otherwise very blurred, when paused.Also, while feature films are almost always shooted at 24 fps, a LOT of TV (I'd say most of it) is shooted at 50 or 60 INTERLACED frames, which means the indidual fields holds a temporary difference, so they hold information that will help us getting the sense of a smoother motion, at a cost of loss of vertical resolution and possibly jagged lines, but video at 50i or 60i IS visibly smoother compared to film at 24p or 25p, this means we CAN see a difference!Computer generated images, when not pre-rendered (like in animation feature films), do not have ANY motion blur, so they can be thought as film shooted with an "infinite" fast shutter speed, this means you'll need MORE than 25 fps to get the same sense of smoothness coming from a film shooted at 25 fps+motion blur.One should really have a look of the latest racing or fighting games on consoles to appreciate that. Since videogame consoles usually (not always, but usually they do) have the frame rate synched to the refresh rate of the TV, they are either running at 30 fps or 60 fps. The difference is VERY EASY to tell apart, and the 60 fps games are usually very highly regarded in the videogaming community.

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As many times as some observers say that this subject comes back to the forums, it obviously still generates responses.Search the Internet and look for the reports that have been published following various studies that have been undertaken

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>However, what we are talking about with regards>to meaningful experience and

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There's plenty of online research touching on the points raised by Umberto concerning the unique problem of motion in computer graphics.scott s..

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Great topic !Sorry for my english...If I read correctly.We / you have elected some parameters for a good moving picture.Moving blurs.Sharpe image.One give us the movement.The other the details.And what we need ?A good "balance".It's a french word, perhaps a good "mix" ?Is there any rule for that ?24 or 25 frames are / were Ok for old CRT television.But today we have LCD or (for me) CRT monitors.Devices with really precise dots.It's even more accurate for LCD.So "bluring" has to be balanced with speed.With that we can put some values.For sure it's depending to everybody percetance.But just for fun if you can.Try to put the same fly on a old classic TV and after on your "up to date monitor".It's not the same world.At the end...As simmers what we want, what we need ?CPU, yes because this sim really need it.A lot of screens ? Yes also. Hundred of fps ?Not sure...

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I find this topic interesting in that I get to show off even more! Well, that's egotistical, it's an interesting topic without me, but here goes:You can ask your eye doctor if he or she know about "geons". Geons were cutting-edge back when I was taking my degree, back in the '80's-'90's, but they still have relevance today. Basically a geon is a pre-rendered shape definition that we all carry around in our brains (so-called "wet-ware"). We have around 2 dozen geons that we can mix and match to make complex shapes that we can easily recognize. Go watch any of the "Terminator" movies and shows. The Terminator Point Of View shots (red screen with white computer overlays) were originally based on geon theory, as James Cameron's special effects gurus were big fans of the theory at the time. Geons are very similar to polygons as used by DX in PC graphics. There are polys that are hard-wired into DX-capable graphics cards to make drawing shapes easier, or at least they were in the early cards.Why talk about geons? There's evidence that geons may be the brain's preferred way of perceiving shapes, but that they are not the whole story. Geons arise from an even more basic cognitive-perceptive concept: that the brain will seek out edges and then fill in the detail of any shape it perceives. Think of a task where you decide to draw an AVSIM Colouring Book for your favourite nephew. You start by drawing the line-art of the aircraft, making the border very bold. You decide your picture is too good to give to your nephew, so you fill in the details and colour it in yourself. That's how the brain is said to work when processing image data.So then the question of smoothness of frame rate versus blurriness/crispness of objects does have a rule, and it's based on biological physiology, and we can call it geon-based perception or Recognition By Components (RBC). Does that really matter? Maybe to game or movie producers who are keen on exploiting human physiology to make a game or video(and yes, there are a few who are clever enough to do that, but it's not easy to be that smart in the long run it takes to publish a video or a game). For most of us, we do what we can to tweak the game or the sim to suit our own needs. We make these changes, it seems, based on instinct. Pretty deep, no?Jeff ShylukAssistant Managing EditorSenior Staff ReviewerAVSIM

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>fps above 25 may not actually be worthwhileThe key fact is that what FPS counter shows you is often NOT true. This is a number averaged over some short period of time so you can even read the number. This counter simply doesn't tell you the whole story.IF the frames in MSFS were coming synchronously one after another guaranteed 1/25 sec apart that would be enough for most of us to perceive smooth motion but the problem is that individual frames in MSFS are coming asynchronously with random spacing and even though the counter may show 25 fps there will be frames that are spaced much farther apart than 1/25 sec causing stutter. It would be nice if locking frames at say 25 fps would actually mean that you are guaranteed that no two frames will ever be separated by more than 1/25 sec.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

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