LOL. I don't ant to beat this to death but I have to take one more shot. You cannot tell the difference between 25 and 35 IF THE IMAGE IS SMOOTH.

 

Now, before it starts a fight let me try to explain what I mean.

 

Smooth - smooth is a yes/no. There is NO almost smooth, very smooth, extra smooth - either it is smooth OR it is not.

 

Now, given that - how do you tell the differrnce between 25 and 35? A little flickering, you say? Then it WAS NOT SMOOTH to start with.

 

The aircraft doesn't go faster, so what do you see?

 

SO I am not saying that someone cannot see the difference in fps but I am saying that, all things being equal (meaning smooth) you cannot - there is nothing to compare against.

 

Lastly, that's not to say that the differences in each system cannot produce smooth at differing FPS - on one system 30 maybe the magic number, on another 60.

 

Just saying I really think we should stop worrying about FPS and consider IQ and smoothness at whatever fps the system likes.

 

Vic

Smooth - smooth is a yes/no. There is NO almost smooth, very smooth, extra smooth - either it is smooth OR it is not.

 

How exactly are you defining 'smooth' as a yes/no?  

 

Here's an extreme and over the top example to illustrate a point.  Let's say someone w/ perfect visual acuity and attention span is observing the full screen video output of a P3D flight scenario.  Maintaining exquisite attention to every detail,  the flight starts, goes ~1 hour to near completion w/ no perceivable hitches, micro-stutter, or other and at the very end, the user noticed a subtle hitch in the VC when panning to look left towards the gate.   This scenario is approaching absolute smoothness.  Our neurophysiology likely will have a 'non-smooth' detection resolution of perhaps, and this is just a wild guess, just over 7 milliseconds, under which a slight hitch could not be perceived.  So in our scenario above, one non-smooth detectable event happened over the course of 1 hour.  Was it a smooth flight then, since it technically wasn't absolutely perfectly smooth?  Since in this scenario there are 3,600,000 million potential non-smooth perceivable events in 1h at 7ms/event, so we will assign a value of smoothness to this flight of 0.9996% perfect smoothness.  Presumably most would argue this fortunate individual had reached the promised land of perfection in terms of smoothness.  But technically, he's not 100% smooth.  And moreover, throw in a few more perceivable events and at some point, he's going to say it's not quite smooth enough.  Moreover, I think there is something to the idea of fluidity in the video, and this quality while hard to define in a negative sense--i.e. absence of negative events like stuttering, seems real to me.  I see this at 60 fps way more than at 35 or even 45 fps.

 

So yes, what does it really mean to say smooth is either yes or no?

 

Sorry, it was raining out I didn't have anything better to do!!

You honestly truly only need 28+ FPS to have a visually smooth experience to the human eye.  

 

 

I'm afraid not. Setting aside the flight model requirements for a decent flow, the human eye comparison doesn't hold here. I think you might be comparing for example video or film (often 24-25 fps). But that is very different from one complete frame to the next in either FSX or P3d, which have no interpolation between frames. In film and most video there is motion blurr. One frame to the next is interpolated unless the object is completely still. This motion blurring helps the eyes to accept the movement as a natural one.

 

In flight simulators the eyes have to instantly adjust from one complete and sharp image to the next image. There is no motion interpolation. The eyes can spot the slightest stutter, glitch or hesitation. In P3d you also need a higher frame rate with almost no stuttering to perceive smoothness. It is not just the image frame rate but the smoothness of panning. We haven't even got to the flight model yet. In procedural flying (ie: navigating, setting the fms and reaching the goal of A to B flying), frame rates aren't quite so crucial.

 

However if you want a flight model to react properly - not just aerobatics but any kind of manual flying where you are pulling some G, doing turns, stalling etc, etc, we know from 15 years experience that flight models need a minimum of 30fps to be decent, and ideally 35 fps without stutters to be reasonably convincing. If you get no fluctuations downwards even for a fraction of a second, or you have zero, and I mean zero, stutters, then you might get away with 28 fps. Below around 28 fps the flight model begins to degrade. At 25 fps and below the nuances of the flight model are utterly lost.

 

Lastly we come to overhead. If you can only achieve 28fps it is not more than just about satisfactory unless your motion is completely stutter free or is absolutely constant. In normal situations if you set 28 fps as a limit, that is the UPPER limit. It doesn't stop the frame rate fluctuating downwards. If your system can manage 35 fps then a small fluctuation down to 28 every so often won't be too bad, but setting an upper limit of 28 fps means there will be fluctuations much lower than this, and it breaks even your own interpretation of perceivable motion. 

 

Please note there is nothing wrong with even 20 fps if you are just going straight and level or doing the gentle procedural flying in a passenger jet. Flying the Extra or similar is a different matter altogether.

 

 

I'm afraid not.

 

That man would know!  He's the REAL deal.  ^_^

@all

Did you ever try to fly a heli with FPS lower then about 30 FPS? Go and try it then you'll notice the difference.

Spirit

I want to use SweetFx, but when i copy the files to my P3D root directory, P3D says: prepar3d was unable to load some program files. When i remove the sweetfx files p3d will start without problems. Is this a known issue or is there a fix/workaround for this problem?

There's a thread abouit SweetFX here at Avsim. Maybe you want to read there?

Spirit

I want to use SweetFx, but when i copy the files to my P3D root directory, P3D says: prepar3d was unable to load some program files. When i remove the sweetfx files p3d will start without problems. Is this a known issue or is there a fix/workaround for this problem?

 

Followed to the letter it will produce some of the best visuals and buttery smooth flying experience possible in P3D with an Nvidia based card without the need of high taxing AA.   Good luck.

 

http://simtweak.com/    <---  SweetFX for P3D for Dummies (Essentially)

 

Of the greatest importance is this line below from the SweetFX setup website linked above.   COMPLETELY disable AA in Nvidia Inspector profile the guy gives you to download (leave all the other settings alone).  It is not needed when you setup SweetFX properly and eliminates stuttering in heavy cloud formations.    I am now capable of flying with 73 miles worth of clouds around me stacked in 8 layers through Active Sky NEXT.

 

P3D2 Known Issues

• SGSS may cause stuttering when clouds are visible. Up for LM to fix.

Noel - OK it's a yes/no as a function of time. If the flight stopped at 30 mins it would be pe4rfectly smooth.

 

B)

 

Vic
 

If we set Unlimited fps and sit at the gate or start of the runway, and go to the outside view and keep the pan button down, what do we see? We see the fps fluctuating in time with the delay taken to draw the next frame. The panning speeds up and slows down as the time to draw each frame changes. Now try for example 20fps fixed, and pan; keep panning, It's smooth. This is what we need to get a proper feel for the plane, especially through turns. If the fps fluctuates during turns it spoils the turn, going straight ahead is more tolerant to fluctuations.

 

With FSX we could get a smooth sim because we could run the sim at a fixed fps that is a multiple of the monitor refresh rate, and use partial vsync (NVidia). So with a 60Hz monitor we can choose 20fps and set 1/3 vsync, or we can choose 15fps with 1/4 and 30fps with 1/2 vsync.

 

In this diagram I'm setting 20fps and 1/3 vsync:

 

 

 

So we can see from the graph that the smoothest setting is to keep the fps matched to the monitor refresh. As soon as we have any fluctuations the sim feels less smooth. Even setting 21fps made the sim feel notchy in the above example.

 

We don't have this luxury with P3D since we can't control the vsync, the program is stuck in desktop miode and does not run in Windows full screen game mode. Instead we can use 120Hz or 240Hz refresh monitors for similar improvements to visual performance.

 

Keeping a consistent fixed fps means keeping a similar time between frames. D3D uses a system of look-ahead frames, or pre-rendering. If the pre-rendering of frames is based on the next few frames, having a known time-between-frames, then it is obvious the physics of the flight model, and environment are pre-calculated more accurately for these frames. This is more important to the flight model than getting 30fps over 20fps.

Maybe when P3D goes 64-bit and DX12 optimized they can do true full screen?

Noel - OK it's a yes/no as a function of time. If the flight stopped at 30 mins it would be pe4rfectly smooth.

 

B)

 

Vic
 

Yes it's always perfectly smooth between non-smooth events!  Despite the thing about 1/2 refresh rate which I used in FSX it still seem way smoother than FSX ever did, especially when you factor in the odd hiccough that would happen in FSX and panning anomalies.  Hands down, superior smoothness in P3D on this machine.  I'm still on version 2.2 but if 2.5 looks decent I will start fresh and reinstall again.

If we set Unlimited fps and sit at the gate or start of the runway, and go to the outside view and keep the pan button down, what do we see? We see the fps fluctuating in time with the delay taken to draw the next frame. The panning speeds up and slows down as the time to draw each frame changes. Now try for example 20fps fixed, and pan; keep panning, It's smooth. This is what we need to get a proper feel for the plane, especially through turns. If the fps fluctuates during turns it spoils the turn, going straight ahead is more tolerant to fluctuations.

 

With FSX we could get a smooth sim because we could run the sim at a fixed fps that is a multiple of the monitor refresh rate, and use partial vsync (NVidia). So with a 60Hz monitor we can choose 20fps and set 1/3 vsync, or we can choose 15fps with 1/4 and 30fps with 1/2 vsync.

 

In this diagram I'm setting 20fps and 1/3 vsync:

 

 

 

So we can see from the graph that the smoothest setting is to keep the fps matched to the monitor refresh. As soon as we have any fluctuations the sim feels less smooth. Even setting 21fps made the sim feel notchy in the above example.

 

We don't have this luxury with P3D since we can't control the vsync, the program is stuck in desktop miode and does not run in Windows full screen game mode. Instead we can use 120Hz or 240Hz refresh monitors for similar improvements to visual performance.

 

Keeping a consistent fixed fps means keeping a similar time between frames. D3D uses a system of look-ahead frames, or pre-rendering. If the pre-rendering of frames is based on the next few frames, having a known time-between-frames, then it is obvious the physics of the flight model, and environment are pre-calculated more accurately for these frames. This is more important to the flight model than getting 30fps over 20fps.

 

That's interesting stuff Steve. I agree that 20 fps is better if it's smooth than 30fps that stutters, or has spikes. But if you are throwing a small aircraft around the sky, even smooth 20 fps doesn't cut it because you will see, or at least I can see, the individual frames. A smooth barrel roll or even tight turn at a constant 33-35 fps, provided they don't spike, is very satisfying compared with 20fps, even if the latter has no spikes.

 

I thought that you can eliminate pre-render by setting a value of 1 in Nvidia |Inspector in the " render frames ahead" section. I don't know if it really works though.

Hey Rob,

 

Just like with twitch games like First Person Shooters, we can't have enough fps. We can turn down the quality settings and choose 30fps at 1/2 vsync, or even 40fps and turn off vsync if we want more fps, but yes smooth is key.