GT5 physics model - how complex is it?

[vandaliser]

Subjective tests are not as valuable as objective ones.

You may have a point if it's just one person like me. But when you got jezza also being positive about GT then it's something.


No offense but i value the opinion of someone who has driven hundreds of cars more than yourself.

 

[robbo6]

I agree that pc sims do it better but that gap that used to be there between console and pc is so small nowadays that one can prefer the better visuals on console to the better physics on pc. I personally think they are very close, clearly.not 100% there yet but too close for the pc elitists from laughing

I dunno, the much better FULL race weekend that PC sims do are MUCH better than what console sims do at the mo. Physics wise....yeah the consoles are a LOT closer, but the PC sims are progressing too. Rfactor2 is going to simulate lock ups properly, be interesting to see how that pans out. Also the setup options on PC sims are better, adjustable steering lock is something that I really like from PC sims...as is proper brake balance and brake strength setups. Then again i fully realise that PC sims tend to be a lot more FOCUSED cars wise. GT and Forza simulate a hell of a lot of varying cars. Although the argument is how unique each car actually is.

I love Console Sims, but they still have a LONG way to go IMO. And I don't think they'll get there as the extra mile of realism (pun intended) is not what the "casuals" want.

 

[HKS racer]

If my friend who used to drive a alfa 146 got gold (by more than 0.8s) on the national b test with 147 on 2nd try but hardly bronze the golf gti on b license test, something must have clicked. Similarly, when I started off, I drove better in my own car, Mazda axela, than other comparable cars. I doubt any simulator can fully capture everything in real life else actual f1 race would be on simulator. Despite many millions invested with many manu different tuning and shared engines, some teams like red bull this season consistently perform better. So there must be subtle differences even the best engineers, equipment and simulator can't identify and match.

Not that subtle, RedBull took advantage of a loophole in F1 regulations, in a few words: the exhaust and diffuser work togheter generating max downforce on rear axis. Fia banned this thing at Silverstone and they lost about 0.8 tents every lap. 0.8 is the difference between destroy a championship and get 2nd 3rd 4th every race. Next year this thing will be banned, at least, this is what they're saying.


Back on topic I think the main problems of GT as a simulator compared to pc sims are the lack of options available:

-No race weekend = LAME.
-No custom championships = LAME.
-Ghost penalties = ARCADE. They need to implement proper flag rules asap.
-The cars never stop going even with full damage on = NOT REALISTIC.

I don't have Forza but I guess even that game suffer from similar things. So this is the difference from console to pc.

 

[Watt2159]

I like it, it feels pretty realistic, and it's fun too!

 

[Sele1981]

I would think that you would need to play FM4 to make any serious claims about FM4's physics or whatnot. I mean folks pointed out issues with your posts in the FM VS GT thread questioning if you even played it and you haven't posted much there ever since 💡

Personally, these games are a lot more complex and advanced today. Console racers are just as advanced as PC racers. Next gen is going to be even more epic!

I dont really understand what you mean? I´ll take a look in the FM vs GT thread. I dont know what you mean... But posting there is a waste. You can say 10 great things about FM and 1 bad thing and they are bashing on you... So I dont care about that thread anymore...

I played FM4 for over 10-20 hrs now. I only play rivals mode because its great. But as I said, I dont like the physics, love my comment or hate it...

I dont know if its realistic or not but I always thought and had the experience with GT that a gamer must be rewarded to not using driving aids. But in Forza you are faster with driving aids. In that Corvette event on road america I think, the top10 drivers use all traction controll. In the GT academy, the fast people disabled every driving aid.

 

[TBR 427]

It's not. There is a fundamental aerodynamic relationship preventing that. For a given wing, the induced drag increases with the square of the lift. In simpler terms, as downforce goes up, drag goes up much faster.

Also in F1, they tend to actually change the wing from track to track. They still need to pick the best operating point on the L/D curve for the wing in use though. In GT5 all you ever need to do is max [negative] L.

And you're looking at the wings, assuming they're in isolation. Which, obviously, isn't the case. And since it's the wing that changes (not an entire aerodynamic package, including the winglets seen at Monaco, etc), the appendages upstream of the rear wing, and of course the diffuser and beam wings below the rear wing, would obviously interfere with the wing.


Do you know which version of the F2007 and F10 are included? That'll help us understand the aero of these cars in the game a bit better I think.

 

[Bushby_23]

Exorcet, do you take into consideration that when top motorsport teams use high down force, they usually lower the gear ratios because it is usually a lower speed track?

 

[Exorcet]

You may have a point if it's just one person like me. But when you got jezza also being positive about GT then it's something.


No offense but i value the opinion of someone who has driven hundreds of cars more than yourself.

That's fine, but objective tests are still better than subjective ones. Someone could go drive around in GT and say it felt great, but if you do a simple test, like putting a car into a slide and then pulling the wheel to correct it and record what happens compared to reality, that is a more valuable test.

A really good subjective opinion is one that can be backed up by an objective test like that.

And you're looking at the wings, assuming they're in isolation. Which, obviously, isn't the case. And since it's the wing that changes (not an entire aerodynamic package, including the winglets seen at Monaco, etc), the appendages upstream of the rear wing, and of course the diffuser and beam wings below the rear wing, would obviously interfere with the wing.


Do you know which version of the F2007 and F10 are included? That'll help us understand the aero of these cars in the game a bit better I think.

But still, for any given configuration, increased lift will increase drag. Aero devices ahead of the main wing might change the the rear wing's angle of attack, lift coefficient, and Reynold's number, but the wing will still produce drag faster than lift as the AoA goes up.

It also stands to reason that the drag/lift trade off goes for complete packages as well, because if a package existed that had the most lift and the least drag, it would be the only one used. Now occasionally something with no downside is found (double deck diffuser), but it's usually only one part of the aero system and it probably still needs to be adjusted to optimize car performance.

I don't know which versions of the F1 cars are in GT5.

Exorcet, do you take into consideration that when top motorsport teams use high down force, they usually lower the gear ratios because it is usually a lower speed track?

I don't see why this matters, as in what part of my argument conflicts with that information? Also, the drag increase is usually much larger than the average force increase from the gearing set up.

 

[hotfoot]

One of the things I've thought for a long time is that PD has come up with a solution that makes driving the game such a unique experience. I think they exaggerate many aspects of car dynamics specifically to make the experience feel more "real" with the limited feedback mechanisms at our disposal. If you've played many other SIMS, one thing you'll notice is that in PD's products the cars feel extremely unique. You will not, even for a second, think that your RUF Yellowbird feel awfully similar to your RUF RGT. Even though they are evolutions of the same car, and even though they both feel very RR, the are also quite different. In every other SIM I've ever played, the cars feel less unique than in the GT series, which I think is key in the attraction GT has in appealing to "car enthusiasts" and not just "motor-sport enthusiasts". The thing is, all PD has to communicate these differences are sight, sound, and FFB in a steering wheel. This isn't even close to the amount of feedback a real car gives. So, how do you communicate the uniqueness of each car? How do you communicate how drafting works (for example)? Well, you exaggerate it sufficiently that the person using your product feel the difference keenly. You make cars that are neutral very neutral, you make cars with oversteer have lots of oversteer, you make cars with a soft suspension very soft and cars with a stiff suspension very stiff, you make drafting give more of a boost in speed than it should. Thus you get the "feel" of the real car through the limited sensations available for PD to work with.

Personally, this is a method that "really works for me" because that's exactly the experience I'm looking for: I want to know "what does driving an AC Cobra feel like? What does driving a Lancia Stratos feel like? etc. I don't know how complex it is, but however PD does it, it is very convincing.

This is a spot - on evaluation. Exactly my thoughts, had this discussion with a collegue. Totally agree. Other games do other things better, but this is the point of GT in my opinion.

 

[hotfoot]

I had a quick go on Forza 4 on my Fanatec. I thought the tyre model felt really good on face value. Seemed very detailed compared to GT5.

 

[trombone]

I don't know if everyone will ever agree on physics, but you can't argue that GT5 is the best car horn simulator on the market!

 

[With a EG6]

I think the Physics engine is not extreme in complexity, but its probably best for real driving feel, at least for a console game that is...

 

[kimi123]

Well I'd disagree there. FM4 is much better simulator. But that's another thread, in fact it's in the Q and A section of the GT5 forum.

Anyway, decided to throw in some numbers

F2007 speed vs downforce.

DF max
223 mph
DF min
212 mph

Essentially no difference. That speed difference is less than the mount the Dodge Viper suffers going from SRT-10 to ACR, and that car has a much less serious aero package.

Peugeot 908

DF max
226 mph
DF min
235 mph (I really hit 233, but I think the power started falling off)

I decided to do some further testing on the 908

2.0 g lift = -1064 lb, .1064 coeff (max DF at GVS tunnel)
1.8 g lift = -701 lb, .086 coeff (min DF at GVS tunnel)

Assuming 10% transmission losses
Max DF drag = 1020 lb (.02 coeff)
Min DF drag = 981 lb (.0178 coeff)

L/D rear wing est
Max DF = 5.32
Min DF = 4.83

The wing is getting more efficient with increased downforce. Highly unlikely. Induced drag rises with the square of lift.

This has nothing to do with physics but the car setup options which is limited in GT5. rfactor is master in this and is having very advanced set-ups. Basically you can model X1 or any type of mod, car you wish to create and play around with setup and various configuration.

 

[Exorcet]

This has nothing to do with physics but the car setup options which is limited in GT5. rfactor is master in this and is having very advanced set-ups. Basically you can model X1 or any type of mod, car you wish to create and play around with setup and various configuration.

When a game violates the laws of physics, that is a problem with the physics.

Wings are not L/D efficient at maximum lift, GT5 is wrong.

 

[kimi123]

When a game violates the laws of physics, that is a problem with the physics.

Wings are not L/D efficient at maximum lift, GT5 is wrong.

There are many advanced physics engine with better collision, deformation as well. GT5 is not good in those as well. GT5 is a driving sim of real cars not a physics simulator

 

[Exorcet]

GT5 is a driving sim

So in other words, it's a physics simulator.

And since it's not simulating physics properly, it's doing its job less well than it could have.

 

[Spagetti69]

So in other words, it's a physics simulator.

And since it's not simulating physics properly, it's doing its job less well than it could have.

Your flogging a dead horse there mate. Believe me.

 

[Bushby_23]

I don't see why this matters, as in what part of my argument conflicts with that information? Also, the drag increase is usually much larger than the average force increase from the gearing set up.

Because you are comparing the top speeds between both min and max aero, and claiming that the speed difference is too low. Unless you work for ferrari and have these figures readily available for the real car, you can't claim anything without taking into consideration the gear ratios, as the difference between a spa and Monaco setup is usually north of 30 kph, if not more.

 

[Exorcet]

Unless you work for ferrari and have these figures readily available for the real car, you can't claim anything without taking into consideration the gear ratios

Yes I can, because the gearing doesn't effect the aerodynamics. The difference in top speed between track A's set up and track B's set up doesn't matter. What does matter is the difference in speed between the wings set up for maximum downforce and minimum downforce. It should be fairly large given that the downforce change is fairly large.

And even though I don't work for Ferrari I could estimate the aerodynamic performance of their cars to a fair degree of accuracy using CFD if I could be bothered putting in the time to CAD the cars. It wouldn't be the first time.

https://www.gtplanet.net/forum/showthread.php?p=5934160#post5934160

But I don't even really need to. I've already shown with back of the envelope calculation that the 908's aerodynamics seem to be off. I could do it for any car.

 

[Dodzzz]

GT5 physics is "perfect" IMO not because it has the most perfect physics engine or whatever, but it's in a perfect balance to please most of the gamers that bought the game. it is simple, fun, and realistic enough.

most people who bought this game only want to win races, get credits, then collect cars, tune it, upgrade it, drive it around, win some more races, and so on.. not to really compete in a tight championship that need tweaks in every little detail like F1 teams currently doing to win races by 0,1 seconds a lap, so IMO, GT5 really don't need that precision & complexity in their physics.

and also note that this game is a driving simulator, not racing simulator. so basically the driving part is the most important, not the racing detail like everyone mention above.

 

[robbo6]

and also note that this game is a driving simulator, not racing simulator. so basically the driving part is the most important, not the racing detail like everyone mention above.

That's a crock. That's JUST a tagline, marketing speak, a blurb etc etc.

The MAIN point of GT5 is to RACE, you do it to earn money and you NEED money in the game. If it was just about driving then every car and track would be unlocked from the start.

 

[Griffith500]

That's a crock. That's JUST a tagline, marketing speak, a blurb etc etc.

The MAIN point of GT5 is to RACE, you do it to earn money and you NEED money in the game. If it was just about driving then every car and track would be unlocked from the start.

I agree that's it's market-o-speak, but most racing simulators (on the PC) have all tracks and cars unlocked from the start (ISI_babyfactory included ), so there is absolutely no distinction in that sense either.

Once again, it pays to use more than a few words (or numbers ) to describe a game.

 

[Bushby_23]

Yes I can, because the gearing doesn't effect the aerodynamics. The difference in top speed between track A's set up and track B's set up doesn't matter. What does matter is the difference in speed between the wings set up for maximum downforce and minimum downforce. It should be fairly large given that the downforce change is fairly large.

And even though I don't work for Ferrari I could estimate the aerodynamic performance of their cars to a fair degree of accuracy using CFD if I could be bothered putting in the time to CAD the cars. It wouldn't be the first time.

https://www.gtplanet.net/forum/showthread.php?p=5934160#post5934160

But I don't even really need to. I've already shown with back of the envelope calculation that the 908's aerodynamics seem to be off. I could do it for any car.

Thats some seriously nice work there 👍

What I was moreso getting at however was when you did the speed test, you werent comparing the gear ratios, so a full max speed test wont quite add up regardless. In saying that, im not saying the physics model is faultless, because I could almost garantee that having more down force on Le Sarthe will be slower in real life compared to a lower downforce setup; something that is reversed in GT5.

 

[Exorcet]

What I was moreso getting at however was when you did the speed test, you werent comparing the gear ratios, so a full max speed test wont quite add up regardless.

Yes, but the point isn't to test the car's max speed. It's to test the effect of drag on max speed.


Some pictorial evidence

Monaco

Monza

Monza


The rear wing is operating at two grossly different cl's for a given speed. And the angle of attack difference is so great that not only is the induced drag going to vary drastically, but profile drag will change a little as well.

I might make a crude F1 car and run CFD on it.

 

[robbo6]

I agree that's it's market-o-speak, but most racing simulators (on the PC) have all tracks and cars unlocked from the start (ISI_babyfactory included ), so there is absolutely no distinction in that sense either.

Once again, it pays to use more than a few words (or numbers ) to describe a game.

Ah but the crucial difference is PC games don't have the "earning money" game mechanic. That is a core part of the GTs since inception and to earn money you race. Whereas in PC games the whole point of the games is to just race in a reasonably accurate depiction of a motorsport championship, so earning POINTS like in reality is the reason for playing.

 

[Tenacious D]

Well I'd disagree there. FM4 is much better simulator.

I'm not sure I can agree with that. I won't exactly disagree, because obviously a lot is going on with Forza 4's physics engine which is remarkable. Some things are reminiscent of Live For Speed, which has incredibly realistic car dynamics. But there are aspects which are very different from any PC sim I've ever played, and make pushing high performance cars around a turn a chore for many of us. I think the only thing which can be said - dare I say it, definitively, is that GT5 gets some things wrong, Forza gets others wrong.

 

[Bushby_23]

Yes, but the point isn't to test the car's max speed. It's to test the effect of drag on max speed.


Some pictorial evidence

Monaco

Monza

Monza


The rear wing is operating at two grossly different cl's for a given speed. And the angle of attack difference is so great that not only is the induced drag going to vary drastically, but profile drag will change a little as well.

I might make a crude F1 car and run CFD on it.

The other thing that no one can simulate in the game. Which is in some ways a shame, but I guess we just have to deal with it.

 

[Griffith500]

Ah but the crucial difference is PC games don't have the "earning money" game mechanic. That is a core part of the GTs since inception and to earn money you race. Whereas in PC games the whole point of the games is to just race in a reasonably accurate depiction of a motorsport championship, so earning POINTS like in reality is the reason for playing.

I suppose GT is a bit far removed from reality in that sense, then. However, in that respect, I guess the real emphasis is on the progress; in being able to gradually amass more money and progressively afford "better" cars, akin to the item / abilities / gear "leveling" in most modern RPGs (which I suppose is where the "GT is an RPG" argument comes from).

In the same way that PC sims are a vehicle for experiencing the particular motorsport niche of interest, perhaps GT is more a vehicle for "experiencing" the individual cars in a range of motoring situations. Which is why the physics are so important, and also why, I feel, GT excels at the characterisation of cars (accurately or otherwise) and translates the virtual idiosyncrasies of fundamentally similar cars - an example immediately in my mind from a few shuffle races recntly: I drove a Celica SS-II (T230), a Clio Sport 2.0 (well, "Lutécia") and an EP Type-R on Eiger back-to-back, and each one was very distinct in the way it handled the different speed corners, down to the steering response and the way the engine "felt" running through the gears - you know, how they drove.

Again, I can't comment on how accurate the experience was, but I think characterisation itself must be heralded as quite an achievement.
I will concede the physics have their flaws, gaping holes even at times, and the racing framework is sub-par compared with other games, but those other games don't have the character or range that GT has, so it really is a case of swings and roundabouts.

 

[JDMKING13]

I suppose GT is a bit far removed from reality in that sense, then. However, in that respect, I guess the real emphasis is on the progress; in being able to gradually amass more money and progressively afford "better" cars, akin to the item / abilities / gear "leveling" in most modern RPGs (which I suppose is where the "GT is an RPG" argument comes from).

In the same way that PC sims are a vehicle for experiencing the particular motorsport niche of interest, perhaps GT is more a vehicle for "experiencing" the individual cars in a range of motoring situations. Which is why the physics are so important, and also why, I feel, GT excels at the characterisation of cars (accurately or otherwise) and translates the virtual idiosyncrasies of fundamentally similar cars - an example immediately in my mind from a few shuffle races recntly: I drove a Celica SS-II (T230), a Clio Sport 2.0 (well, "Lutécia") and an EP Type-R on Eiger back-to-back, and each one was very distinct in the way it handled the different speed corners, down to the steering response and the way the engine "felt" running through the gears - you know, how they drove.

Again, I can't comment on how accurate the experience was, but I think characterisation itself must be heralded as quite an achievement.
I will concede the physics have their flaws, gaping holes even at times, and the racing framework is sub-par compared with other games, but those other games don't have the character or range that GT has, so it really is a case of swings and roundabouts.

Grith you should be a MOD man your post are the best to read man. You always have some good input on things and at the same time you keep it real.

 

[kimi123]

So in other words, it's a physics simulator.

And since it's not simulating physics properly, it's doing its job less well than it could have.

PC sims have physics engine with heavy emphasis on customization of setups. So you can play around with various settings and car will react accordingly. GT5 is not made like this. They have basic physics engine based on car specification and then they do some research about the cars handling characteristics and try to simulate that in the game. That is how they are do going by this video: