Sigh - here we go again.

IF your sim is smooth and looking good at 22 it will look just as good in the turns. IF it does not and you need 45fps to look good - your system is not configured properly BUT it is YOUR system and if you are happy with it - enjoy.

But I can do 360 degree turns around a point in P3D att 22fps with no problems.

 

Vic

This discussion is coming up every now and then.

There are people saying they have a smooth experience at frame rates as low as 20 fps or even lower. Other people are saying they need 30 fps or more or they can even see a difference between 30 fps and 60 fps.

 

Unfortunately the most essential aspect most of the time is missed.

No matter how high the fps are, everything that appears on a screen always is a sequence of single frames. The perception of a smooth movement in the end is an optical illusion created by the eyes and the brain. The most important part of the „system“ in this regard is the user's brain.

https://en.wikipedia.org/wiki/Frame_rate

https://en.wikipedia.org/wiki/Motion_perception

At what frame rate the brain is capable of creating the illusion of a smooth movement is highly individual and depends not only on biological prerequisites but also on training, habituation and focus.

It is just like the famous picture where you can see a young or an old woman depending on what your brain is focussed on.

http://psylux.psych.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/html/perceptual_ambiguity.html

Some people see the young woman, others see the old woman. After some training most people are able to „switch“ between them.

 

With single frames or smooth motion it is the same. If the brain concentrates on seeing single frames it will most probably see single frames. And the more the brain tries and trains to recognize single frames the more it will be able to do so. The frame rate at which single frames are perceived gets higher and higher. In the end the brain might even be able to see a difference between 30 and 60 fps. While this might be an impressive ability of the eyes-brain-system – it ruins the sim experience.

But the brain can also be trained and habituated in the other direction. If the brain focuses on perceiving a smooth motion it will probably see a smooth motion. The more the brain tries and trains to perceive a smooth motion the lower the frames can get for the brain to manage to do so. In the end the brain might be able to perceive a smooth motion even under 20 fps. Those are happy simmers.

 

Of course the less movement of the scene the easier it will be for the brain to perceive a smooth movement. Without any movement at all even 1 fps is „smooth“. Looking at a tennis match (with a fast moving ball) 60 fps might not be enough. That is why „stutters“ are most easily perceived when flying low, fast and turning sharply. So when flying a B747 most probably a lower fps rate will do than when doing aerobatics.

And apparently the brain can hardly perceive a smooth motion if the frame rate is unsteady. The brain needs a steady frame rate to create the optical illusion of a smooth movement. That is why it is essential to have the sim run at a steady frame rate (by limiting the fps in the sim or by using VSync and the the refresh rate of the monitor).

 

What frame rate is the lower limit for the brain to be able to create the illusion of a smooth movement will probably be individually different and depending on training and habituation. Since movies have been shot at 24 fps for decades without people complaing about stutters that might be a good hint that the average brain is able to create the illusion of a smooth motion at 24 fps.

 

After all a recommendation for those who now need 30 fps or more (and still see stutters or would like to increase their graphic settings) might be:

- Set the sim rate to something between 20 and 25 fps.

- Adjust the sim settings so that this frame rate is achieved steadily.

- Stop looking at the sim rate.

- Stop looking for stutters.

- Try to see a smooth movement and enjoy flying.

The brain will adapt to that frame rate over time. Not within minutes or hours. It takes weeks or even months.

After a few months of habituation most people would probably be able to enjoy a smooth sim at around 20 fps (except for inevitable lags when complex new scenery / textures get loaded).

 

5 hours ago, RALF9636 said:

This discussion is coming up every now and then.

There are people saying they have a smooth experience at frame rates as low as 20 fps or even lower. Other people are saying they need 30 fps or more or they can even see a difference between 30 fps and 60 fps.

 

Unfortunately the most essential aspect most of the time is missed.

No matter how high the fps are, everything that appears on a screen always is a sequence of single frames. The perception of a smooth movement in the end is an optical illusion created by the eyes and the brain. The most important part of the „system“ in this regard is the user's brain.

https://en.wikipedia.org/wiki/Frame_rate

https://en.wikipedia.org/wiki/Motion_perception

At what frame rate the brain is capable of creating the illusion of a smooth movement is highly individual and depends not only on biological prerequisites but also on training, habituation and focus.

It is just like the famous picture where you can see a young or an old woman depending on what your brain is focussed on.

http://psylux.psych.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/html/perceptual_ambiguity.html

Some people see the young woman, others see the old woman. After some training most people are able to „switch“ between them.

 

With single frames or smooth motion it is the same. If the brain concentrates on seeing single frames it will most probably see single frames. And the more the brain tries and trains to recognize single frames the more it will be able to do so. The frame rate at which single frames are perceived gets higher and higher. In the end the brain might even be able to see a difference between 30 and 60 fps. While this might be an impressive ability of the eyes-brain-system – it ruins the sim experience.

But the brain can also be trained and habituated in the other direction. If the brain focuses on perceiving a smooth motion it will probably see a smooth motion. The more the brain tries and trains to perceive a smooth motion the lower the frames can get for the brain to manage to do so. In the end the brain might be able to perceive a smooth motion even under 20 fps. Those are happy simmers.

 

Of course the less movement of the scene the easier it will be for the brain to perceive a smooth movement. Without any movement at all even 1 fps is „smooth“. Looking at a tennis match (with a fast moving ball) 60 fps might not be enough. That is why „stutters“ are most easily perceived when flying low, fast and turning sharply. So when flying a B747 most probably a lower fps rate will do than when doing aerobatics.

And apparently the brain can hardly perceive a smooth motion if the frame rate is unsteady. The brain needs a steady frame rate to create the optical illusion of a smooth movement. That is why it is essential to have the sim run at a steady frame rate (by limiting the fps in the sim or by using VSync and the the refresh rate of the monitor).

 

What frame rate is the lower limit for the brain to be able to create the illusion of a smooth movement will probably be individually different and depending on training and habituation. Since movies have been shot at 24 fps for decades without people complaing about stutters that might be a good hint that the average brain is able to create the illusion of a smooth motion at 24 fps.

 

After all a recommendation for those who now need 30 fps or more (and still see stutters or would like to increase their graphic settings) might be:

- Set the sim rate to something between 20 and 25 fps.

- Adjust the sim settings so that this frame rate is achieved steadily.

- Stop looking at the sim rate.

- Stop looking for stutters.

- Try to see a smooth movement and enjoy flying.

The brain will adapt to that frame rate over time. Not within minutes or hours. It takes weeks or even months.

After a few months of habituation most people would probably be able to enjoy a smooth sim at around 20 fps (except for inevitable lags when complex new scenery / textures get loaded).

 

Same thing happened with TV, and a person seeing flicker in a TV image due to the refresh rate. The NTSC system in the US used 30FPS ( actually 29.95) and in Europe, it was PAL at 24 FPS. People traveling from the US to  Europe, would complain that when they watched TV in Europe, the image seemed to flicker. After a couple of days, they got used to the 24 FPS and didn't noticed any flicker.   

The 24Hz TV image appeared to flicker In the UK because it was beating with the 50Hz lamp frequency. Back then, phosphor persistence prevented flicker within the image, along with retina image persistance. This is why CRT monitors took to using 70Hz to 90Hz to help prevent that beating, especially with striplamps.

15 minutes ago, SteveW said:

The 24Hz TV image appeared to flicker In the UK because it was beating with the 50Hz lamp frequency. Back then, phosphor persistence prevented flicker within the image, along with retina image persistance. This is why CRT monitors took to using 70Hz to 90Hz to help prevent that beating, especially with striplamps.

Not my experience, even in a totally dark hotel room, co workers that traveled with me to Europe a few times a year, all video professionals, would complain about the flicker in a dark hotel room when watching PAL TV. After a day or two, they didn't notice it. BTW, pro Video was my field during most of my working career. 

4 minutes ago, Bobsk8 said:

Not my experience, even in a totally dark hotel room, co workers that traveled with me to Europe a few times a year, all video professionals, would complain about the flicker in a dark hotel room when watching PAL TV. After a day or two, they didn't notice it. BTW, pro Video was my field during most of my working career. 

Then I suspect you would know about the beating problem.

In the CRT days the image was also interlaced, and with the phosphor persistence gave rise to smearing and making it hard to notice stagger during panning. A complicated problem with low persistence digital panels arises because the location of objects in each frame is very clear, panning can be a big problem. Extreme example of image persistence was with the moon footage where the horizon could be seen through the space suit.

P3D is different to FSX as it has functions applied to the image to improve effects like fog which can appear very slightly behind the scenery position in a fast turn or roll and appear to look like stutter. So where FSX can work well with 20fps, P3D may not work so well at low fps, especially with stunt aircraft requiring 30+fps. In a sedate aircraft I'm using 19fps locked on a 59Hz monitor.

 

P3D is also different to FSX in that it utilises the desktop view and places a D3D image in a window. In full screen this is just a desktop sized window with caption and borders removed. The P3D display setting VSync=On will limit the fps to the refresh rate of the monitor. This may be too high to serve any purpose on a high frequency monitor, giving rise to smooth looking P3D with big monitors that only do 30Hz and stutter on monitors running at 60Hz or more. The NVidia controls allow a profile to be made to allow 30 fps or other, effectively limiting the monitor frequency but can look poor when moving the mouse around.

 

Problems are reduced by ensuring the sim can run at a very consistent frame rate, using locked fps requires a lot of power since it creates look ahead frames. It's a mistake to think that if we can see 40fps unlimited we can use 30fps fixed. In fact any tiny amount of delay and a look ahead frame is used up, with only 40fps available would take many frames to build back the look ahead frames making it useless unless we can see 60+, even 90fps would work nicely with 30 fixed.

Having noticed slight lack of fluidity in several games even with constant 60fps+vsync using borderless window mode which become perfectly smooth on switching to exclusive fullscreen makes me think it might have its own share of micro stutters in p3d despite the triple buffering in addition to from fluctuating and low fps.

Yes, with exclusive mode the frame does not have to coincide with the monitor refresh frequency to remain smooth, with the desktop we have to improve the coincidence by using methods to keep the frame rate consistent and using sub multiples of the monitor frequency, for example 15 20 30 or 60fps on a 60Hz display.

15 hours ago, RALF9636 said:

At what frame rate the brain is capable of creating the illusion of a smooth movement is highly individual and depends not only on biological prerequisites but also on training, habituation and focus.

Thanks Ralf that is good food for thought but it is a flawed argument. The more frames there are per second, the more information there is for the brain.

When flying gliders at low altitude or doing aerobatics at low altitude, I need higher FPS to give me more information about what is happening in the air. I will probably have to move over to another simulator, but currently there is none.

I find it hard to believe that P3D being a military simulator, is a 20fps simulator. Hopefully that will change but for now I will try this:

Freedom is slavery

smooth low fps is real