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Author Topic: Drop in framerates with FSDT in P3D4  (Read 4613 times)
Morten
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« on: June 17, 2017, 12:34:19 AM »

Although I much appreciate FSDT's scenery conversion into P3D4, I notice a severe drop in framerates compared to the exact same FSDT scenery and settings inside FSX - in my case this means a 40% drop down in P3D4 and even worse when using Dynamic Lighting.
As it is I simply can't use any of this converted scenery.

According to this article,
https://www.avsim.com/forums/topic/512651-14jun17-how-not-to-mess-up-a-perfectly-good-prepar3d-v4-installation/
using Dynamic Lighting is actually a good test in order to determine whether the scenery has been correctly converted into P3D4, or not. Unfortunately it seems that something has gone wrong in this case, which leads me to ask you if these conversions actually have been exported the proper way, which means, ONLY through the SDK tools provided from Lockheed Martin?

Morten         
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specialist
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« Reply #1 on: June 17, 2017, 01:23:31 AM »

So many factors can cause reduction of frame rates, and although I haven't made the switch to P3Dv4, perhaps wont either, I've read many threads in different forums about the issues they are having with poor frame rates. I think that many folks bought into the idea that 64bit meant no more frame rate issues. More like VAS or OOM issues is what they may not be having to deal with now, but folks just want to crank up their sim to the highest settings, not realizing that 64bit is not going to help that. Hardware limitations among other things can cause frame rate loss.
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virtuali
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« Reply #2 on: June 17, 2017, 01:36:46 AM »

You can't really say "I use FSX at the same settings", simply because you don't have ANY of the most demanding settings in FSX to begin with, like realtime shadows, cloud shadows, realtime reflections. Even when the slider looks the same, the sim is not doing nearly the same thing, like in Autogen, that P3D V4 draws (by default) using the much demanding Speedtrees.

I have much better fps in P3D V4 than FSX, even with Dynamic Lights enabled, and I have much better quality too.

The thing in the scenery that will affect dynamic lights the most, are the ground textures, assuming the scenery won't use its own dynamic lights, which only a handful use right now.

Since I don't like to make statements without actual testing, I made some tests, activated the display of the Average fps, which is the most accurate and useful to know so, these are average fps. And I tested with the default 737 imported from FSX, because I wanted to be sure I was testing the scenery, not the airplane itself. P3D V4 treats landing lights as a special case so, regardless if the airplane itself is "native" or from FSX, the landing lights are proper "real" dynamic lights so, I purposely used a not very demanding airplane, to put the airplane used out of the equation.

I don't think anyone would doubt that, if the problem was the scenery, the airplane used shouldn't matter, all other things being equal.

So, here's the results:

KCLT, which uses native P3D ground mesh/polygons, exported with the P3D SDK, sitting on RWY36C:
Landing lights On = 57.0 fps, with a 7.0% variance.
Landing lights Off = 59.1 fps, with a 5.0% variance.

KIAH, which use native FSX ground mesh/polygons, exported with the FSX SDK, sitting on RWY33R:
Landing lights On = 63.3 fps, with a 6.0% variance
Landing lights Off = 65.1 fps, with a 5.0% variance

LSZH, which use an FS8 ground mesh/polygons, exported with the FS8 SDK, sitting on RWY34:
Landing lights On = 54.7 fps, with a 5.0% variance
Landing lights Off = 54.7 fps, with a 4.5% variance

Note that, the most common case of airport sceneries, by far, are those using the FS8 ground polygons! We were always a bit different than the other developers, by using the native FSX format even for ground polygons, but you'll find that most sceneries out there still use the FS8 format.

But, as you can see from these tests, it doesn't seem the SDK used to make the scenery has ANY relationship with the impact of dynamic lights, surely not on our sceneries, but I cannot possibly guarantee it will be the same for every scenery out there. It's well known the FS8 code is slower, which is why we got rid of it years ago, starting with KDFW, but there's no evidence the FSX format is slower than the P3D one. KIAH it's just a less demanding scenery than KCLT, and that explains the fps difference between the two.

However, this test was made with Antialiasing at its lowest value, which is 2xMSAA. It's very well known that, more than everything else, what REALLY kills the fps with dynamic lights, it's the Antialiasing mode. So, putting that one at 8xSSAA, which is the better quality mode, the results become:

KCLT
Landing lights On = 29.1 fps, with a 4.5% variance.
Landing lights Off = 49.5 fps, with a 6.0% variance

KIAH
Landing lights On = 33.2 fps, with a 5.5% variance.
Landing lights Off =61.4 fps, with a 5.0% variance

LSZH
Landing lights On = 35.8 fps, with a 6.0% variance.
Landing lights Off =55.5 fps, with a 6.5% variance

But until now, I wasn't running with full screen, since I was writing this post at the same time. So, I went full screen, which in my case is 2560x1440, and see what happens, with the same highest quality antialiasing 8xSSAA:

KCLT
Landing lights On = 13.9 fps, with a 5.0% variance.
Landing lights Off = 31.1 fps, with a 4.0% variance

KIAH
Landing lights On = 34.8 fps, with a 4.5% variance.
Landing lights Off =14.9 fps, with a 3.5% variance

LSZH
Landing lights On = 17.2 fps, with a 6.0% variance.
Landing lights Off =29.8 fps, with a 6.5% variance

So, it's quite clear that, what kills performances with Dynamic Lights, are ANTIALIASING and RESOLUTION, which are basically the same thing, since increasing the antialiasing, it's just a way to force the video card to draw more pixels, as if it was running on a resolution higher than the screen.

The kind of SDK used to create the scenery doesn't seem to matter, not with our sceneries, which I chose to display 3 very different methods of creating ground polygons.
« Last Edit: June 17, 2017, 01:49:53 AM by virtuali » Logged

virtuali
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« Reply #3 on: June 17, 2017, 01:41:57 AM »

I think that many folks bought into the idea that 64bit meant no more frame rate issues.

Exactly. In fact, while in 32 bit you couldn't push your settings too high, because you risked an OOM, now because the sim won't OOM anymore, one might be tempted to set the setting so high, that no hardware will be able to keep up with it.

But, at least, with a 64 bit app, you can BUY more hardware to fix this and, even if the current generation video cards might still struggle, the next one and the ones following, will surely work much better, while on 32 bit, even the best hardware in the world wouldn't have helped much against OOMs, because it was a limitation of the software.
« Last Edit: June 17, 2017, 01:48:20 AM by virtuali » Logged

specialist
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« Reply #4 on: June 17, 2017, 01:47:46 AM »

But, at least, with a 64 bit app, you can BUY more hardware to fix this and, even if the current generation video cards might still struggle, the next one and the ones following, will surely work much better, while on 32 bit, even the best hardware in the world wouldn't have helped much against OOMs, because it was a limitation of the software.

That is true, and boy we can expect to be upgrading with all the possibilities that lie ahead in the sim world.
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Morten
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Posts: 76


« Reply #5 on: June 17, 2017, 11:05:06 PM »

So many factors can cause reduction of frame rates, and although I haven't made the switch to P3Dv4, perhaps wont either, I've read many threads in different forums about the issues they are having with poor frame rates. I think that many folks bought into the idea that 64bit meant no more frame rate issues. More like VAS or OOM issues is what they may not be having to deal with now, but folks just want to crank up their sim to the highest settings, not realizing that 64bit is not going to help that. Hardware limitations among other things can cause frame rate loss.

Either you haven't read my post at all, or your answer simply was meant for another post! I would suggest, when calling yourself for a "Specialist", that you at least start out with trying P3D4 before you rub your shoulders in here.

------------------------------------------------
Anyway, thanks for your profound answer Virtuali!
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marknie
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« Reply #6 on: October 17, 2018, 03:25:59 AM »

There is definitely something seriously wrong with KLAX by FSDT in P3d V4.whatever. .  .   I get maybe some drops to be expected at Flightbeams KSFO but KLAX is really really bad.  I go from 22fps to 9fps!!!  Crazy.  That scenery truly needs to be re-worked!!!
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virtuali
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« Reply #7 on: October 17, 2018, 09:39:45 AM »

There is definitely something seriously wrong with KLAX by FSDT in P3d V4.whatever. .  .   I get maybe some drops to be expected at Flightbeams KSFO but KLAX is really really bad. 

There's nothing wroing with KLAX, that has VERY good fps in P3D4, and doesn't require any fix. See this video here:

<a href="http://www.youtube.com/watch?v=NJnFeWU32hk" target="_blank">http://www.youtube.com/watch?v=NJnFeWU32hk</a>

Quote
I go from 22fps to 9fps!!!

22 fps is already VERY bad.

You shouldn't wonder why you think KLAX dropped it to 9, you should ask yourself why it was so low to begin with. As explained so many times already on the forum, if your system is so overloaded with stuff and with unreasonably high settings that was already running to an unbearably low fps as yours already was, it's absolutely normal it will drop even further with a detailed scenery.
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