Physics questions/discussion

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danowat

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Danowat32
Danowat32
Firstly, I wouldn't be suprised if these questions were unanswerable outside of the GT5 dev team, but for the sake of open discussion, I wouldn't mind hearing others thoughts.

To me, physics are (one of) the biggest draw of racing sims, and I am still left wondering how GT5p's physics are programmed.

I would be interested to know if the tyre physics are based on any specific tyre models, i.e. Pacejka curves, were any of the older GT's based on any tyre models, or were they, and GT5p, based on PD's own tyre curves?.

I would also like to see the inclusion of a telemetery view, ala Forza 2, simply to see what exactly is going on in the background of GT5's physics, I know most of GT5's demographic wouldn't be interested in this, but seeing as GT5 is aiming for drivers with more realistic hardware, I would think that a larger portion of the new GT5 drivers are indeed interested in what goes on "under the hood", because at the moment, I can't get over the feeling that most of GT5's physics are fudged.

Lastly, I am interested in the difference between standard physics and professional physics, as to me, it just seems like professional physics has the "LOUD" button turned on.

For those who don't know, the LOUD button on a stereo is a bit of a fake, because all it does is raise the bass and treble by 2 notchs to give the impression of "loudness", I believe that the professional physics selection is just the same, and all it does is turn down the grip by a few notches to give the impression of more realistic physics.

I would be interested to hear any (constructive) feedback, because with the inclusion of physics as realistic as something like Live For Speed, GT5 would be a dream come true.
 
Live for speed has some good physics, but on the other hand the cars have a strange way of sliding. When you drift with a road car, at the end of your drift you should be having all the trouble of the world to prevent the car from slipping the other way. Not in GT5:P, nether in LFS, this is simulated correctly.
At the end of a drift the car resumes its normal driving line and there are NO forces at ALL pushing the back in the other direction.
Offcourse with racing cars these effects are countered by modified parts and settings, but I'm just talking about road cars here, like there the cars you start with in LFS.
 
Firstly, turning off any type of aids would show the realism and difference between standard and professional.
second..
If you are using a wheel set, it is much easier to notice the difference between standard and professional physics, reason because the amount of throttle you apply can be precisely done which throttle response leads to over steer - under steer.

Many people might think that the professional physics is merely a less grip no driving aid setup. But the truth is, if you used a wheel set (any 900 degree rotation wheel), you will notice actually you have more control of the car because the physics are more precise in implementing a realistic experience.

Whereas the standard, if you used a wheel set despite having 900 degrees rotation the handling will be within 180 degree rotation.

The handling is prone to more under steering despite having all driving aids turned off. Why? Because the key is, standard does not create a major difference (reaction in different applications to throttle and the timing) in throttle response.
 
geez tuff opening post brother.......but for the sake of physics I gotta ask are you playin with a G25, because if you is not, the physics do feel a bit lame with a DFP. I for one loved the tyre based physics of EPR and thought GT5p was a great let down, but after the gettin a G25, all is well. Still I would like better simulation of weight tranfer and body roll, not to mention burnout physics, but for this we'll have to wait till full GT5.
 
Yes, I finally plugged my G25 that I use for LFS and other PC sims into the PS3 this morning, and I am still left lacking by, I think, the tyre physics, something just ain't right, and I can't put my finger on what it is.

As for LFS, it's certainly not prefect, but IMO, it is the pinnicle of racing sim physics, and has yet to be matched, let alone surpassed.
 
I'm not sure that I'm correct but I have the feeling that the standard physics are more natural (not entirely) than the professional physics.

I practice (private lessons) in real life in a professional auto training school, going from defensive car control, offensive, power slides, theoretical lessons etc... 2 years ago I had the change to learn how to power slide with a Porsche 997 S on a special designed anti skid track. The track was very wet (obviously) and the speed wasn't that high, around max. 60 - 70 km (also obviously). I'm just telling this to let you know that I have a little bit of experience irl and think that I can make a comparison with GT5p.

The professional settings in GT5p feel almost as difficult as irl on this wet track with the 997. In GT5p you have a little bit more grip.


I have to mention that I have set the streering options in the main menu to simulation. You can choose between Amateur, Professional, Simulation.






:)
 
Very odd, it's almost like he had a blow out, or mechanical failure of some kind.

But yeah, you can save slides like that quite easily in LFS, I have driven the FZ5 (a Porsche like rear engined, rear drive car) quite extensively in leagues, and have had similar slides and saves.

Like I said, LFS isn't prefect, it would be silly to think it is, but ATM, it's the best there is.
 
Actually my point is: You think racing sims are realistic, but we still have a LONG way to go.
That Audi didn't have a blowout, he was doing 160km/h when he steered a bit too harsh, the back steps out and he corrects it too late.
 
My Opinion :)
I think GT5P have one of best Physics for a car racing sims to date. Sure LFS may have awesome physics, and for me, somehow car's seem not handle as good as they should in real life, Besides, I don't really want to talk about LFS since it's only in ALPHA stages, it will take many years for that game to become a full and best sim out there..

Back to GT5P, I don't know why we do complain about TYRE physics, when Gran Turismo games always offered close to life circuits times over other sim racing games. But only complain I have is when you are in grass at low speeds.. too much sliding? I don't know, I never experienced going 100 MPH into grass... But I did drive my car in my back yard, and Since I have a RWD car, little gas will make my rear tires spin, just like in GT5P, but in GT5P even nose slides too much at low speeds in grass.
 
NoxNoctis Umbra
But only complain I have is when you are in grass at low speeds.. too much sliding? I don't know, I never experienced going 100 MPH into grass... But I did drive my car in my back yard, and Since I have a RWD car, little gas will make my rear tires spin, just like in GT5P, but in GT5P even nose slides too much at low speeds in grass.
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The grass is obviously not meant to be realistic, it is an anti cheating measure. Not perfect, but its probably better than just adding to the lap time like in FM2, when the guy cutting the corners still wins the race, its just that his lap times which don't effect the result at all are a lot slower.

I have always wondered why people rave about LFS. I have not spent that much time with the game due to the rubbish nature of PC online play, but it just seemed to be far too easy to be realistic to me. I could drift that rx-7 alike like a D1 king all day. Might have to download again and take another look sometime. To be honest it does not bother me if one game is a little more realistic than another. GT is already far better than LFS in most regards, who cares if LFS may or may not be slightly more realistic in one specific circumstance or another.
 
Previous GT games had massive errors in the slip angles of the tyres amongsed other things. The poor tyre model was put on display by tourist trophy.

The tyre model in say GT4 was like driving in a wet polished carpark. Some traction, the wheels spin and you have none. Something similar to the original versions of LFS

I think the original question that was asked tho is how does the physics differ between pro and std other than grip levels. To say the car under or oversteers more just states that.

Telemetary view would showcase the physics model if its good. And would give valuable feedback if the driver were inclinded to setup the car suiting their style.

If the tyre model is out, the whole car is out as that is its contact patch for the circuit. Just like a real car's setup may be perfect, but if he has granite tyres, its not going to be fast.
 
NoxNoctis Umbra
Back to GT5P, I don't know why we do complain about TYRE physics, when Gran Turismo games always offered close to life circuits times over other sim racing games.
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And there in lies the problem, physics artificially fudged to make joe bloggs lap similar times to professional racing drivers.
 
I don't think it is possible yet to take all the factors into account that determine the feeling of a car. Do you have any idea what an engine the game would need?
It should be taken so much into consideration:
- track temperature/status (wet/dry)
- air tempurature
- humidity
- wind direction
- wind speed
- tyre tempurature
- type of asfalt
- tyre wear
- tyre pressure
- tyre deformation
- fuel load (shifting of weight)
- flat spots on tyres
- brake types
...

If they'd had to implement all factors for each car.. That's impossible my friend.
Besides, these are not known values such as torque, power, weight... How do you express maximum braking power, maximum grip level, ...?
 
You dont need all those to get correct representation on how a car handles

track temp/status is modeled in other sims be and hopefully will be modeled :)

air temp and humidity dont have to be there

wind speed/direction is already modeled in many games

tyre temp should be modeled

tyre pressure is or should be modeled

tyre deformation is modeled in lfs

tyre flat spots are modeled in many sims

weight distribution of fuel should be modeled

brake types should be and is modeled in many sims

type of ashphalt can be modeled by having slip angles different for different types of ashphalt. They already model different types of surface. Road, grass, sand. Different ashphalt & concrete types isnt out of the question and is something im hoping to see.

You can still have it without a lot of those options and have a good physics model complete with an acurate pacejka model. Its not out of the question. But i guess the real question is what is the consumer demand for those features, and what can a ps3 calculate combined with the need for good graphics? Hardcore simracers is a niche market and although appealing to have all that modeled, it takes a lot of time, which in turn is a lot of money. Maybe in the full release we'll get some of these, if not hopefully some time in the future.

Sims are simulations, so its unrealistic they will be 100% accurate but hopefully GT5 will give good feedback and be as realistic representation of the cars as they can be on this platform, and by the sounds of what i've read its what they're hoping to do. A lot of companies do claim thats what they've produced tho so fingers crossed till the full release!
 
I use the Dual Shock Controller, and there's a HUGE difference when driving STANDARD or PROFESSIONAL.

What's obvious to me is that I am MUCH FASTER with standard than professional, mainly due to more tire slippage on professional. It is imperative that I get the wheel so that I can compete in the Time Trials...

wingwing85
Firstly, turning off any type of aids would show the realism and difference between standard and professional.
second..
If you are using a wheel set, it is much easier to notice the difference between standard and professional physics, reason because the amount of throttle you apply can be precisely done which throttle response leads to over steer - under steer.

Many people might think that the professional physics is merely a less grip no driving aid setup. But the truth is, if you used a wheel set (any 900 degree rotation wheel), you will notice actually you have more control of the car because the physics are more precise in implementing a realistic experience.

Whereas the standard, if you used a wheel set despite having 900 degrees rotation the handling will be within 180 degree rotation.

The handling is prone to more under steering despite having all driving aids turned off. Why? Because the key is, standard does not create a major difference (reaction in different applications to throttle and the timing) in throttle response.
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Thanks for shedding some light! :embarrassed:
 
Here is an excellent article on Wikipedia entitled Comparision of Racing Simulators . It's collections of matrix's which compare whether a racing simulator calculates certain factors.

I've heard many people claim one sim is superior to another, but after reviewing this article, you'll be quick to realize it's all shades of grey. Racing simulators as a genre still have a long ways to go!

The original posters point of the "Loud" button and GT Prologue or others "faking" it is accurate. They all fake it for certain aspects. There isn't a sim out there that even calculates everything. And just saying they calculate something doesn't even consider whether they do it correctly or not.

When I see someone on any racing forum say, "The physics for XYZ sim/game are perfect!" it makes me cringe. No sim is perfect. Some are better than others, but the more you know the more you realize we have a long way to go still. Personally, I'm all for more advanced sims, so I hope the bar keeps getting raised higher and not dumbed down.
 
danowat
And there in lies the problem, physics artificially fudged to make joe bloggs lap similar times to professional racing drivers.
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joe bloggs, you mean pro drivers too ... right? i hope you have seen some videos and magazine articles were pros can have their GT lap times very close to real life lap times.

Every single sim game out there does not have the capability to reproduce real life physics, simple as that. There are just to many factors to consider. They simply try to mimic real life feel in combination with a lot of physics, key word "feel". And on this, GT series have proven to be doing a good job.

just my thoughts.
 
tinram
joe bloggs, you mean pro drivers too ... right? i hope you have seen some videos and magazine articles were pros can have their GT lap times very close to real life lap times.

Every single sim game out there does not have the capability to reproduce real life physics, simple as that. There are just to many factors to consider. They simply try to mimic real life feel in combination with a lot of physics, key word "feel". And on this, GT series have proven to be doing a good job.

just my thoughts.
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I don't know if this is accurate, but to me it looks like those lap times are slower than what you can do in GT5P...

http://www.fastestlaps.com/track4.html

This is from GT4 (so maybe not really valid in this discussion, but you get the point):

http://www.youtube.com/watch?v=rkdWkAs9qmo
 
jibber
I don't know if this is accurate, but to me it looks like those lap times are slower than what you can do in GT5P...

http://www.fastestlaps.com/track4.html

This is from GT4 (so maybe not really valid in this discussion, but you get the point):

http://www.youtube.com/watch?v=rkdWkAs9qmo
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I assume you are comparing this lap times to gt5p online records. Without fear of repercussions, like destroying a car or killing your self, online lap times should be faster than real cars as your second video has said. But a car driven by the same pro driver, driven the same way with the same car on the same track, lap time should be quite close.
 
in reply to the loud button comment, that would have to assume pd designed their physics models on how the car currently drives in standard mode...rather ridiculous. more likley they designed their physics models on how the car currently drives in professional mode then allow you to dumb that down for standard mode....i find it hard to believe after all their research they decided that standard is as close tothe real thing as they could get.
 
Great discussion!

Since LFS is the defacto "best sim" standard it's right that we compare GT5P to the standard.

I'm very impressed by this video:

http://www.youtube.com/watch?v=L023Gxp4pWM

When I compare sims I first look at videos--internal cockpit views and external views. GT5P looks most realistic. The cars move just like the cars I see in Top Gear.

I think LFS has better tire sounds and the cars tip over or just tilt a little when you slide over a rumble stip. That makes "the physics" appear more realistic.

And of course LFS has damage.

If GT5 had damage and cars that could roll over and better tire sounds and more car bounce then it would be better than LFS physics wise IMO.

In LFS I find the cars too easy to drive. Especially the high powered race cars.
 
-- Bear in mind that I haven't yet played GT5P (but played the other earlier GTs) and just judging it from videos and reading others' impressions on it online, but have been driving various PC sims for the past few years. --

One very significant simulation aspect that LFS is the detailed suspension geometry modelling, which ends up translating well into the game's handling and force feedback implementation. Obviously, trying to model hundreds of suspension setups accurately for GT5 is going to be far too time-consuming (getting the geometry right is one thing, making it deliver the right feel is another). Not to say that this is bad, because at the moment, a GT5P on pro physics replay displays handling behaviour almost exactly like another PC favourite of mine, netKar.

On the subject on tyres, I applaud LFS' approach to modelling a tyre itself, but it has a long way to go . I'm still in a love/hate relationship with it, so I'd take a simpler approach like what GT5P is using today. Anyway, can someone here give an opinion on how similar/different GT5P's pro physics is when compared to GT3 with simulation tyres?

Oh, and without a doubt the biggest thing that is missing from any virtual driving experience is the natural G forces. It's funny that the forces that tend to scare us in real life, when they go missing in games, we end up craving badly for them. And most of us actually compensate for this loss by driving much more aggresively without even realising it.

There's hope on the horizon though...

http://www.youtube.com/watch?v=ld6xT5yfbhw

:D :D :D
 
whlspn
There's hope on the horizon though...

http://www.youtube.com/watch?v=ld6xT5yfbhw

:D :D :D
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The ultimate problem I have with LFS is that in order to really test the accuracy of a sim you need to be able to compare game lap times with real life lap times. But you can't do that with fake cars and fake tracks.

People may claim something "feels" right but what matters are raw numbers. If you can get 5 cars to each produce identical lap times as real life on 5 separate tracks AND produce real life straight line acceleration, max speed and braking then I say you probably nailed the physics.

Force Feedback quality is much more subjective.

Oh, that video is awesome. Can I would pay $1,000 for that G-force simulator but I doubt it's that cheap. :(
 
I'm happy to see so much great, in-depth physics discussion from so many new members. :)

MowTin
The ultimate problem I have with LFS is that in order to really test the accuracy of a sim you need to be able to compare game lap times with real life lap times. But you can't do that with fake cars and fake tracks.

People may claim something "feels" right but what matters are raw numbers. If you can get 5 cars to each produce identical lap times as real life on 5 separate tracks AND produce real life straight line acceleration, max speed and braking then I say you probably nailed the physics.
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Sorry, but I disagree completely. The problem with lap times is that any number of factors can lead to them matching up with real-life -- cars that are too fast on a track that is too big, cars that are too slow on a track that is too small...and those are relatively simple flaws (though solving them may not be so simple). There are many, many other faults that could collude to produce the "right" result.

In the end, pretty much any game with any physics engine could be set up to "look" about right and produce laptimes identical to the real thing. Hell, you could even do it with an SNES Mode 7 game (think the original F-Zero, original Mario Kart), though it probably wouldn't fool anyone.

It doesn't end there -- the thing to remember about examining "the numbers" (ie. in-game telemetry) is that they come from the game itself. If a particular car is supposed to produce x amount of lateral grip, of course the simulated car is going to report that it's producing x amount of lateral grip (assuming the developers paid attention to such details). But how are we supposed to know that x in the game would be x in real life?

It's for these reasons that I personally believe the focus of driving simulator physics evaluation should not be on the performance numbers, but on handling dynamics at and beyond the limit of traction. Of course the numbers should still match up on a good simulator, but the importance of those numbers pales in comparison to good understeer/oversteer simulation, IMO.

As such, I have no problem with LFS's lack of real cars/tracks, and I adore it for its understeer/oversteer simulation, which is lightyears ahead of anything else I've played. :)
 
Wolfe
In the end, pretty much any game with any physics engine could be set up to "look" about right and produce laptimes identical to the real thing. Hell, you could even do it with an SNES Mode 7 game (think the original F-Zero, original Mario Kart), though it probably wouldn't fool anyone.
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That's why I said 5 different tracks. You could fake results on one track but how would you fake it for 5 different tracks?

Imagine a simple L shaped track portion. If in-game the car takes the same amount of time to reach the end of the first straight as the real car on real L shaped track and if the total time taken is the same then clearly on the bend the game driver wasn't able to exceed the real life speed or the real life brake point or begin accelerating earlier than real life into the second straight.

Why didn't the game driver just take the bend faster? Because he didn't have enough grip. Why didn't he start accelerating earlier exiting the bend? Because he would oversteer/understeer and crash.

Again that's just a simple L shape but imagine a game getting times close on a number of different tracks with many different complex turns. That would prove they're doing something right.

Racing is really about keeping you braking, throttle and steering inputs as close to the grip limit as possible. And I think the best measure of grip limit is real world car/track comparissons.

I'm eager to see how the GT5 cars' Top Gear test track lap times compare to the real world numbers.

LFS is great...I own it but no one can say, "I own an XRT and the LFS XRT is rubbish because my car doesn't drive like that at all." In GT5 you hear plenty of people comare their real cars to the game cars. If you're "simulating" you need to simulate real things or else how is anyone supposed to objectively rate the quality of your simulation.
 
I haven't get a chance to play with standard physic much, but I think it's absolutely not just a "loud" button. It's not just less grip but greater change in grip level when you go beyond the optimum slip angel. So this means if you turn the wheel too much, it will understeer more on professional. This concept also applies to the rear slip angle, ie. grip level drops more dramatically when you over-rotate the rear causing more severe oversteer.

The effect of weight transfer is also different, causing more oversteer/understeer from weight transfer.

Pro Physics required more precision of drivers' inputs. Less grip means you just need to go slower, brake earlier, etc.
 
MowTin
produce real life straight line acceleration, max speed and braking then I say you probably nailed the physics.(
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this is one aspect I would love to see in the game as I have been alittle disappointed in previous attempts.0-100kph, 1/4 mile and top speed should be as close to manufactures times (after a couple attempts) and would add that feel of realism.
 

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