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Do AI aircraft spawn

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starling View Drop Down
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    Posted: 24 Apr 2013 at 11:10pm
Bristol EGGD is my test airport for T360 and with a lot of expert help from forum members I've now got the AI activity quite nicely balanced. As long as I start FSX sometime between 07:00 and 09:00 GMT that is!

Starting FSX during this period (sliders at airline=32 and GA=51) always kicks off with a full house - all airline parking spots occupied and a few scattered business jets and light GA. Departures soon result in vacant parking and thereafter the mix of departures and arrivals give a pleasing and varying range of activity with periods of quiet and occasional queuing for take off. This balance runs through into late evening. However if I start FSX later in the day it can take an hour or so before a pleasing balance of AI activity is achieved.

So to my question:

I have just included a simple 2 leg flight plan (Air Malta) to Malta that is scheduled to depart about 11:30 am. It is the only Air Malta flight plan.

If I start FSX some time between approximately 10:00 and 11:30 I always see the Air Malta aircraft parked up ready to depart - and it departs more or less on schedule. If however I start FSX at 07:00 the Air Malta aircraft will not be there as all non-GA parking is occupied by aircraft scheduled to depart before 11:30.

Assuming a 07:00 start for FSX, by 08:00 (and thereafter) there are ALWAYS several free airline parking spots.

My question is: If I allow the sim to run itself from 07:00 will the Air Malta aircraft spawn into a vacant parking spot so that it can depart according to the flight plan schedule? In other words, will FSX spawn an aircraft into a parking-spot four and a half hours into the game in order to meet a flight plan schedule?

I appreciate I can test this for myself - and I will when I get the time. I'd just be interested to know "what there is to know" about FSX AI spawning .

Ok, I know FSX is really about the user actually "flying" an aircraft not watching AI. However sometimes AI can be an interesting diversion and if knowing more about how it works can help create a more immersive flying experience then......why not.

Bruce
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freddy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddy Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 2013 at 2:31am
Short answer: No, the Air Malta will not "spawn" there.

Long answer: FSX goes to great lengths and is coded specifically to try to maintain the best realism possible and eliminate "surprises" like aircraft suddenly appearing, *pop*, out of thin air. If you are sitting in an aircraft in a parking spot NEXT TO the vacant spot where an aircraft magically and suddenly appears, *POP* out of thin air, then that would be extremely unrealistic, and annoying. FSX tries hard not do this.

However, FSX *WILL* spawn aircraft in to the sim based on various factors. For example, AI aircraft will spawn in the air, at a certain distance from the airport, and then resume their flight plans to their destinations. The USER (that's you), will not see this occur because it happens away from the airport; away from where YOU are. Similarly, the sim will "throttle" (delete) aircraft out of the sim based on certain factors. Again, the USER will generally not notice this. Your USER aircraft (where YOU are) has a radius around it. It's a BUBBLE actually, with you at the center. Anything heading away from and out of this bubble is "throttled" (deleted). And anything heading toward and in to this bubble is spawned. This is one way that FSX keeps its frame rates under control. It only looks after the planes that it needs to look after; those that are near you. It makes no sense for the sim to load in thousands of AI planes and try to manage each and every one of them. The frame rates would be very bad.

Obviously, when you first run and load FSX, it spawns all the relevant aircraft at your airport (inside your bubble) ready to go. The spawned planes then begin their roles ... either remaining parked (not time to leave yet), following their flight plans (if they are in the air) preparing to land at or fly to their destination, etc etc. If there are not enough parking spots to spawn all of the parked aircraft, then some kind of randomness occurs and FSX just loads in enough planes to take up the available spots. But, once a plane leaves, and a spot gets freed up, no, a plane that didn't initially get loaded (for example, your Air Malta) will not spawn *POP* in to that spot.

Things can be VERY busy in the first minute or two after you load up and run FSX. Every AI plane that gets spawned in to your bubble has to work itself out and do whatever it is set to do. This is why you will see LOTS of activity, and departure after departure after departure, at an airport when you first load the sim. The AI will eventually settle down, smoothing itself out, with things beginning to appear "normal" and not as hectic, after about 5 or so minutes.

Yes, it is great fun watching AI. Especially if you have the correct airlines and liveries, at the correct airports, with real-world schedules (or as close as you can get them). AI is one of the things that FSX does do quite well. Sure, you get your blemishes, glitches and frustrations with AI from time to time ... But, when things are scheduled correctly and working as expected, FSX does a fantastic job of it. And Traffic X and Traffic 360 (and indeed the other traffic programs out there) are great tools to have.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote starling Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 2013 at 10:15pm
Freddy - Many thanks for your very detailed explanation of the FSX spawning (and throttling) process.

I'm thinking it would be useful if the radius of the bubble could be varied to take into account location and frame rate. For example, when I'm flying the PMDG 737NGX at London Heathrow my frame rates are typically about 13 fps with my "normal" AI settings (in practice I reluctantly tweak my setting). From what you've just told me I suspect that the poor frame rate could in part be due to AI activity arriving and departing the VERY busy London Gatwick and London City airport (and maybe even Luton Airport) as well as Heathrow own activity. In that situation a smaller "bubble" size that excluded (some/most of) Gatwick and London City AI activity would help frame rates significantly (I would have thought).

I've always thought there must be a reason why frame rates change depending upon the direction I'm facing. This is particularly apparent when taxiing the PMDG 737 at Heathrow. I'm guessing that there must some other cause other than the AI activity bubble.

Do you know how far into the future FSX looks when deciding to spawn aircraft at FSX start up? If at a low activity airport there was mostly weekly scheduled flights (maybe nothing for today), would FSX spawn aircraft due to depart in the next few days for example?

Bruce
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddy Quote  Post ReplyReply Direct Link To This Post Posted: 26 Apr 2013 at 1:01am
Unfortunately, the size/radius of the user "bubble" cannot directly be changed. There's no slider for it in the sim. The only way to really reduce frame rates with AI is to turn down the TRAFFIC PERCENTAGE slider in the sim, thus reducing the number of AI aircraft the sim has to manage and look after. Obviously, yes, at a busy airport like Heathrow, there are going to be a lot of AI planes, and hence frame rates can suffer. Turning down the traffic percentage slider helps in situations such as these. Like you, I RARELY change my Traffic Percentage slider. So it makes sense to try to choose a Traffic Percentage slider setting which achieves the best "compromise" between not having enough AI planes when I am far away from busy places, and having way too many planes when I close to busy places. About the only time I change my Traffic Percentage slider is when I am flying in Europe. Traffic X has LOTS of planes in that airspace, and I need to adjust my slider when flying there. I imagine that this would be the same for Traffic 360 as well.

Your frame rates will also be affected by the plane that YOU are flying. The default FSX B737 will be more friendly on frame rates than the PMDG 737 at a place such as Heathrow ... simply because the default B737 is not modelling as many (complicated) systems as the PMDG one.

Additionally, with Traffic X and Traffic 360, it is possible to add the default FSX planes in as AI. Doing this can also adversely affect frame rates as the default FSX planes are NOT AI planes. They have avionics systems which get modelled, and more detailed moving parts etc. Even though the sim might be flying them as AI, the sim is still modelling the working systems and parts ... thus adding to and affecting the frame rates. So if you are thinking of adding the default FSX planes in as AI, keep this in mind.

How far does FSX look in to the future when deciding to spawn and throttle (delete) AI planes? And for weekly schedules, does FSX mainly spawn aircraft due to depart in the next few days ... as opposed to planes that are due to depart today in the next few hours? I am not sure how it works it all out. That said, I don't think it loads a plane if it is not set to depart TODAY. So, even if an airport is not all that busy and only has weekly scheduled planes, I think it only loads in those planes that are scheduled for departures TODAY.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote starling Quote  Post ReplyReply Direct Link To This Post Posted: 26 Apr 2013 at 10:35pm
Freddy - Had some time on my hands today so decided to run a simple test to check out (in part) the FSX spawning timeframe:

I found a UK airfield that had plenty of GA parking and little scheduled FSX AI activity. Duxford Airfield (EGSU) seemed to fit the bill nicely.

I created a weekly VFR flight plan (Cessna 172) departing 12:00 GMT Mondays.

Starting FSX on Monday 11:50 the Cessna pushed back on schedule at 12:01. It arrived back at Duxford more or less on schedule at 15:43.

I tried starting FSX on Monday 14:00. The Cessna was not at the airfield. This of course was correct as it was still inside it's flight plan.

I started FSX at various times of day on Tuesday and the Cessna was always parked up.

I did the same for Saturday and Sunday with the same result.

The test shows that, for a weekly VFR flight plan, FSX will spawn the aircraft up to 6 days ahead of departure - if there are parking spaces available. The thing with Duxford is that there are ALWAYS free parking spots so we don't know for sure how FSX would handle spawning in a busy airport situation. My (fairly confident) guess is that, for %-slider qualifying aircraft, parking places are filled on a "first to fly" basis until all suitable spots are occupied.

In setting up this test I found a definite bug in T360. When selecting the day of the week for a weekly flight, T360 sets the plan for the NEXT day of the week. So for example, if I select Sunday in T360 the flight plan will be created for a Monday departure.

Thanks for the info in frame rates and advice cautioning against adding default planes to the AI fleet.

Bruce
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddy Quote  Post ReplyReply Direct Link To This Post Posted: 27 Apr 2013 at 1:07am
Originally posted by starling starling wrote:

The test shows that, for a weekly VFR flight plan, FSX will spawn the aircraft up to 6 days ahead of departure - if there are parking spaces available. The thing with Duxford is that there are ALWAYS free parking spots so we don't know for sure how FSX would handle spawning in a busy airport situation. My (fairly confident) guess is that, for %-slider qualifying aircraft, parking places are filled on a "first to fly" basis until all suitable spots are occupied.

A good test. And, yes, now that you mention it, I do believe I have seen this behaviour from FSX (loading planes on a "first to fly" basis until all suitable spots are filled).

Ahhh ... see ... you are on your way to understanding AI.


Originally posted by starling starling wrote:

In setting up this test I found a definite bug in T360. When selecting the day of the week for a weekly flight, T360 sets the plan for the NEXT day of the week. So for example, if I select Sunday in T360 the flight plan will be created for a Monday departure.

This is not a bug with Traffic 360.

FSX is different from FS9 in the way it numbers its days. In FS9, the week started on Sunday (which, for programming purposes, is assigned the number 0). In FSX, the week was changed to start on Mondays (and thus Mondays in FSX were now assigned by the number 0). You don't need to care about the assignment of the number 0, that's just internal programming stuff invisible to users. But, because FSX continues to use the exact same AI tools (no change) that were used by FS9 for compiling AI flight plans, what it means is this ... When compiling flight plans for FSX, flights which would have departed on Sunday in FS9, depart instead on Mondays in FSX. If you happen to copy your flight plans in to FS9 and compile them, then you will notice the days change.

As long as you are aware of this, then you can take it in to consideration when compiling flight plans. It would have been nice of Just Flight to adjust for this in the program by showing the "actual" departure day in the user interface, or by adjusting the schedules during the file creation process so that they compile with the correct day selected by the user. Although, to be fair, I suppose doing any of that would subsequently cause confusion if you use the program to create schedules for FS9. At the very least, it should have been mentioned in the manual. But, Just Flight haven't done any of that, so you just need to be aware of it and work with it.


Originally posted by starling starling wrote:

Thanks for the info in frame rates and advice cautioning against adding default planes to the AI fleet.

No problem. Worth mentioning is that I do have the default FSX planes added in to my schedules. But, I've only added the GA ones and the Learjet; not the commercial jet airliners. I am actually NOT noticing any great reduction in my frame rates. However, that said, there are plenty of web pages and forum posts all over the Internet which warn about the potential frame rate loss when doing this (perhaps they are talking more about adding the commercial jet airliners, as opposed to the GA planes and Learjet?). The caution would certainly be very relevant if you added and started to make flight plans for more complicated planes, such as the PMDGs. I suppose the point is this .... if you are cautious and spread the flight plans around so there are not concentrated appearances of the same planes, and you don't add in any of the big commercial planes or complicated PMDG types, then the results can be satisfying (all provided, of course, that your computer hardware is able to cater well enough for it).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote starling Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2013 at 2:27pm
Thanks again for the info freddy - interesting background to the problem.

Any idea why frame rates vary depending on viewing direction. Again using the PMDG 737 at Heathrow as an example, frame rates can vary by 6 or 7 fps depending upon which compass direction I'm looking (I use EZdok). It doesn't matter where I am in the airport or which way the plane is facing - just the direction I'm looking.

I know that EZdok is not the culprit as I've tried disabling it and frame rates still vary as I change taxiing direction.

Bruce
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddy Quote  Post ReplyReply Direct Link To This Post Posted: 29 Apr 2013 at 2:34am
Frame rate variances based on the direction you are viewing (as opposed to the direction your aircraft is actually facing) ... nope, sorry, I have no idea.

A suggestion: If you are not already using a frame rate limiter (program) with FSX, then you might want to download and try one. It may "smooth" out the frame rates for you and "correct" that issue. Do a Google search on the term "fsx FPS Limiter" (no quotes of course) and go from there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote starling Quote  Post ReplyReply Direct Link To This Post Posted: 29 Apr 2013 at 9:34am
Will give it a try - Thanks .

Bruce
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Soaranden Quote  Post ReplyReply Direct Link To This Post Posted: 29 Apr 2013 at 10:51pm
Originally posted by starling starling wrote:

Any idea why frame rates vary depending on viewing direction.


It has to do with the number of draw calls required. In general, the greater the number of objects in view at an airport, the greater the amount of processing that was required to create that view. The number of draw calls also increases when there are more objects in view that do not share the same textures.

Dan
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddy Quote  Post ReplyReply Direct Link To This Post Posted: 30 Apr 2013 at 10:03am
Interesting. And makes sense too.

(I think I've learnt something new today; and it's always good to learn something new.)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote starling Quote  Post ReplyReply Direct Link To This Post Posted: 30 Apr 2013 at 10:05am
Thanks Dan .

Bruce
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ranger Quote  Post ReplyReply Direct Link To This Post Posted: 03 May 2013 at 3:16pm
I noticed a while back this change in frame rate can be very obvious at LHR, I noticed when on Runway 9L facing right(towards all parked aircraft) frames could go below 10, face left away from any traffic or parked aircraft, the frame rate increases dramatically.

Cheers Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote starling Quote  Post ReplyReply Direct Link To This Post Posted: 04 May 2013 at 9:51am
Thanks Mike.

I use EZdoc camera and I've found that I can improve frame rates by increasing the zoom rate slightly. At smaller addon (or stock) airports I normally use a zoom of 0.82 with the PMDG 737NGX VC - increasing to a zoom of 1.00 gives me a more workable frame rate* at the "UK2000 Xtreme" Heathrow addon airport.

This pretty much ties in with Dan's explanation as increasing zoom reduces the field of view so reduces the draw call rate.

*.....however, I still need to slightly "dial down" some of the FSX settings and turn off shadows to get frame rates of 20+ with the PMDG737NGX/UK2000 Heathrow combo.

Bruce
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