Racing in the Rain: Are GTR2 WetGrip parameters bogus?

[Shovas]

Looking to get some discussion going on racing in the rain in GTR2 and if it's being implemented properly

Here's a video where I show how WetGrip=1.0 (100%) is actually more realistic than the default 0.75 values which are commonly used in tracks, both by SimBin and modders.

Below the video I've copy&pasted my thoughts from the video description on what's going

Sorry, audio is out of sync, watch it muted to avoid being confused.

Video is 100% rain in the ESR WTCC 2010 BMW 320si at VLM Mid-Ohio

GTR2 knows you're driving in the rain even when Location GDB files set WetGrip parameters to 1.0 ("100%" grip just like in dry) and it models wet surface grip levels. GTR2 is modeling a wet surface, at some level of its isiMotor engine. It's not saying you have 100% of dry grip, it's saying that whatever GTR2 is modeling for a wet surface, you have 100% of that grip. Adding in less than 1.0 WetGrip values fakes less grip. I don't think WetGrip values are even needed. I think they've even broken the isiMotor simulation of rain driving.

What I did here was simply take VLM Mid-Ohio's GDB file and set WetGrip params to match dry grip params:

RoadDryGrip = 1.00
AIDryGrip = 1.00
RoadWetGrip = 1.0 // DEFAULT=0.75
AIWetGrip = 1.0 // DEFAULT=0.75

My dry time in the same car, same track was 1:29.901 and my best wet time with the new WetGrip values was 1:32.201 so, even with WetGrip=1.0, so you can see and prove there's a wet surface and grip levels being modeled.

My theory is that SimBin used these crazy different WetGrip values (commonly 0.75) to exaggerate the rain driving experience for keyboard or controller users or for users of early sim era ffb wheels that couldn't really deliver a good experience. Add to that they had already messed up with subpar PLR FFB parameters and no wonder they had to do something to communicate to the user a wet driving experience.

If they had proper PLR FFB, like we do now with SHO FFB or RealFeel FFB I don't think these fake grip levels would have ever been needed.

 

[jgf]

The tires also have a wet grip parameter for each compound, so this will factor in to the track settings also.

 

[Shovas]

TIW noted my wet times were overly fast compared to real life differences between dry and wet racing and I did notice AI didn't adjust for WetGrip at 1.0 they seemed to be acting like it was 0.75 still. That tells me they're trained or configured in Talent RCD files to drive in the wet in a certain way.

So there's issues that get introduced with WetGrip=1.0 even though I'm still convinced it's a more realistic rain driving experience :/

 

[IMC '67]

TIW noted my wet times were overly fast compared to real life differences between dry and wet racing

I was going to point that out as a 2 seconds difference in lap times between the dry track and the fully wet track is way too small. I'm using a RoadWetGrip value of 0.45 for my rainy 1967 Spa race together with P&G tyres to achieve authentic and realistic lap times in the wet.

 

[The Iron Wolf]

So, maybe worth sharing a bit of context here. Shovas and me are investigating RFP FFB getting signficantly lighter in rain compared to dry condition (I am pretty sure built in FFB has the same behavior). _I think_ a bit lighter is realistic, but in GTR2 it drops too much. I am considering adding simple additional force multiplier into CCGEP to compensate for that drop in steering force in rain based on surface wetness, but of course, ideal solution would be to find combination of settings that does not require the new feature.

 

[Shovas]

I was going to point that out as a 2 seconds difference in lap times between the dry track and the fully wet track is way too small. I'm using a RoadWetGrip value of 0.45 for my rainy 1967 Spa race together with P&G tyres to achieve authentic and realistic lap times in the wet.

I like the accurate lap times, I really don't like the driving experience

 

[Spinelli]

Looking to get some discussion going on racing in the rain in GTR2 and if it's being implemented properly

Here's a video where I show how WetGrip=1.0 (100%) is actually more realistic than the default 0.75 values which are commonly used in tracks, both by SimBin and modders.

Below the video I've copy&pasted my thoughts from the video description on what's going

Sorry, audio is out of sync, watch it muted to avoid being confused.

Video is 100% rain in the ESR WTCC 2010 BMW 320si at VLM Mid-Ohio

GTR2 knows you're driving in the rain even when Location GDB files set WetGrip parameters to 1.0 ("100%" grip just like in dry) and it models wet surface grip levels. GTR2 is modeling a wet surface, at some level of its isiMotor engine. It's not saying you have 100% of dry grip, it's saying that whatever GTR2 is modeling for a wet surface, you have 100% of that grip. Adding in less than 1.0 WetGrip values fakes less grip. I don't think WetGrip values are even needed. I think they've even broken the isiMotor simulation of rain driving.

What I did here was simply take VLM Mid-Ohio's GDB file and set WetGrip params to match dry grip params:

RoadDryGrip = 1.00
AIDryGrip = 1.00
RoadWetGrip = 1.0 // DEFAULT=0.75
AIWetGrip = 1.0 // DEFAULT=0.75

My dry time in the same car, same track was 1:29.901 and my best wet time with the new WetGrip values was 1:32.201 so, even with WetGrip=1.0, so you can see and prove there's a wet surface and grip levels being modeled.

My theory is that SimBin used these crazy different WetGrip values (commonly 0.75) to exaggerate the rain driving experience for keyboard or controller users or for users of early sim era ffb wheels that couldn't really deliver a good experience. Add to that they had already messed up with subpar PLR FFB parameters and no wonder they had to do something to communicate to the user a wet driving experience.

If they had proper PLR FFB, like we do now with SHO FFB or RealFeel FFB I don't think these fake grip levels would have ever been needed.

Not sure I'm understanding. You want full wet laptimes to only be 2.3s slower than fully dry? They should be like, I don't know, 15 - 30 seconds a lap slower. I'm talking brutally wet conditions, not a light drizzle obviously.

I like the accurate lap times, I really don't like the driving experience

Ohhh, OK, nevermind then, ignore my message above, I think I understand now. Basically you don't want lower, more realistic grip levels because it highlights negative/undesired physics of the car and/or game and/or game-engine much more obviously than higher grip levels. That makes sense and I can totally understand your POV and your comment about the lap time VS driving experience.

My advice (not that you asked for it)? Don't worry what's realistic or whatever. Just have fun and do what you want and keep sharing your info/experiences with us all.

Having said that, I was driving the Lotus Elise in the full wet - vanilla GTR2 track & track settings (eg. grip values) - at Barcelona and I had a TON of fun but...having said that...the Elise is probably the least powerful car in the game...plus...I was going back and forth with 2 different car-"physics" mods: HQ ("High Quality") and RP ("Reborn Project"). Both have, in my opinion, substantially better & more natural driveability & control during oversteer - at least in the wet - than the vanilla Elise.

I was using close to default FFB settings with my SC2 Pro as it was a quick test so I didn't spend time tuning it and it was still fine but, then again, I tend to like different FFB from a lot of people. I don't care much about rear feel and "return-to-centre" SAT through the actual FFB itself, I'm heavily dependant on front-tyre grip being conveyed. OK, this is quite irrelevant to your discussion - sorry - I'm just rambling now

Are you using the vanilla cars?

P.S. I'm just starting the career mode of GTL. Once I finish that, I plan on moving to GTR2. When I do that, I can join you in digging deep into GTR2 if you'd like. I notice you spend a lot of time with it. I can help test all sorts of things out for you if you'd like.

 

[Shovas]

Ohhh, OK, nevermind then ignore my message above, I think I understand now. Basically you don't want lower, more realistic grip levels because it highlights negative/undesired physics of the car and/or game and/or game-engine much more obviously than higher grip levels. That makes sense and I can totally understand your POV and your comment about the lap time VS driving experience.

I mean to say I think the default lower grip levels in the rain are less realistic... at least as far as intuitiveness in driving experience goes

I think they've only achieved more realistic laptimes through other hacks like Talent RCD files, for instance

Edit: After comparing real onboards, I no longer believe the physics are incorrect, it's more about the ffb feel

My advice (not that you asked for it)? Don't worry what's realistic or whatever. Just have fun and do what you want and keep sharing your info/experiences with us all.

For me, I rarely let go of something until I've come to terms with it. Like with RealFeel, I didn't understand that for years, now I'm a full convert So this is sort of part of enjoying the sim for me.

Having said that, I was driving the Lotus Elise in the full wet - vanilla GTR2 track & track settings (eg. grip values) - at Barcelona and I had a TON of fun

If you compared your experience to real-world rain racing, would you say how it felt mirrored what you see in onboards or broadcast?

Edit: After comparing myself, I found the default WetGrip values to be largely accurate to real life onboards.

Are you using the vanilla cars?

I switch back and forth quite often

P.S. I'm just starting the career mode of GTL. Once I finish that, I plan on moving to GTR2. When I do that, I can join you in digging deep into GTR2 if you'd like. I notice you spend a lot of time with it. I can help test all sorts of things out for you if you'd like.

Cool, yeah, GTR2 is my main sim so I always like to look for ways to improve it.

 

[Shovas]

Good example in a BMW M3 at a swamped Spa

 

[IMC '67]

Driving any of the cars that has fairly final physics in my 1967 sportscar game feels what I would like to think is realistic at a soaking wet Spa using a RoadWetGrip value of 0.45 and P&G tyres, with the exception of maybe a bit too light feeling in the steering force like the Iron Wolf pointed out.

The difference between the dry track pole time (3:35.600) and the fastest lap in the wet race (4:03.500) was almost 28 seconds at the real 1967 event. In the video I posted above I'm doing lap times of around 4:05 at best, driving the Ferrari 330 P4 which was slower than the pole sitting Chaparral 2F which also had the fastest lap in the race.

Jacky Ickx in the Mirage M1 passing the pits at the 1967 Spa 1000 km race

As for more modern cars and tracks close to the original GTR2 content, I was at the 2002 FIA GT Championship race at Anderstorp where the pole time in the dry (1:30.255) was over 11 seconds faster than the best lap in the wet race (1:41.603). It can be difficult to find info on fastest lap times in the wet as most races aren't fully wet from start to finish and hence the published best lap time is usually set in improved conditions.

A Lister Storm is leading the way at Anderstorp 2002

 

[C_Stephens]

Once you settle on a grip value you like is there a way to increase say the rolling resistance of the wet tire to broaden the gap in laptimes?

 

[jgf]

broaden the gap in laptimes

That is done with the "AIRange=" in the track AIW file.

 

[Spinelli]

What would be awesome is a mod with way longer & thicker spray. I had a couple different rain spray mods/files which I compared back and forth. Although different from eachother, neither had enough spray if I remember correctly; I should test them again though.

 

[Shovas]

Can you talk more about the P&G tyre you're using @IMC '67? Did you tweak it at all?

Grippiness loss at 0.45 must feel significant but does the tyre bring it back?

What does it feel like to drive?

 

[IMC '67]

The cars feel like I would imagine them to feel in the wet except maybe for the amount of lesser steering force. So basically less grip than in the dry with longer brake distances and easier to lock up under braking. More understeery in corners if not getting the speed down and more oversteery if getting on the gas too early. Watching my Spa video should give a good idea of how the 330 P4 drives in the wet.

No significant P&G tyre grip tweaks for the player but lots for the AI. I'm using the mid 60's Firestone, Goodyear, and Dunlop tyres from various cars and always try to pair them with similar cars in my game.

Here's also an older post where I talk more about the tyres.

 

[The Iron Wolf]

maybe for the amount of lesser steering force.

Glad to see I am not the only one bothered by this. I am almost sure I will be adding a multiplier to compensate for that.

Do you remember if drop in FFB steering force is related to track wetness, like 20%/50%100% do they drop force increasingly? Thanks.

 

[Shovas]

Okay, so I was just basically straight wrong about WetGrip.

I took that M3 at rainy Spa video, studied it for steering, throttle, and brake input action, and then compared it to GTR2 with the M3 at Spa with 100% rain and, guess what, SimBin was probably basically right. I went back and forth between the video and GTR2 all the time tuning WetGrip values. I only started to approach what it looked like in that onboard video as I approached the default 0.75 value for WetGrip. SimBin 1 - Shovas 0.

*I think 0.75 is too convenient of a round number to have been really dialed in but I have to admit it reproduces input requirements the closest

Observations:

1. Looks like default WetGrip=0.75 reproduces the steering, throttle, and brake inputs more closely than higher grip levels compared to the reference video

2. Important: Completely opposite Grip Factor values (before: 0.98125, after: 0.01875, Grip Weight unchanged for both) provide much more confidence of corner entry in the rain . "It's like maybe the game isn't faking me out with reduced wheel weight." You do lose ffb understeer information mid-corner but the confidence outweighs that in the rain (and you can still visually judge understeer).

3. In the dry, I care more about understeer while, in the wet, I care more about oversteer - and it's not a small preference.

4. The good news is this means it's not about physics so much as ffb expression and so we won't have to affect AI laptimes to get where we want to be.

5. While WetGrip isn't the answer, I think it's agreed the "feel" (ffb) is subpar in the wet.

6. I still want to experiment more with Grip Factor and Grip Weight because I know when I go back to the dry I won't like not having as much ffb understeer information.

*This may turn out be another wrong assumption. Only AB testing will confirm. Doing that right now and in normal non-understeer scenarios I really like the new lower Grip Weight in the dry. We'll see how I feel when I'm at the limit in understeer situations, though...

7. I suggest modulating RealFeel FrontGripEffect based on rain percentage as there is some uncertainty between one set of parameters working between wet and dry.

I was doing this testing on a true vanilla install just to be sure I had a proper baseline so that's why I was in the PLR and not tuning RealFeel but the observations are still helpful for RealFeel tuning as things like RealFeel's FrontGripEffect have the same/similar effect as PLR Grip Weight.

Grip Weight tuning notes:

 

[The Iron Wolf]

7. TIW's idea of modulating RealFeel FrontGripEffect based on rain percentage seems to be the correct course of action at this time.

To be clear I am leaning towards modulating the entire steering force, not RFP FGE alone. I am going to check how FGE affects FFB in rain but in my experience entire steering force drops and I want simplest and most logically comprehensible solution rather going down the fight with infinine combination of track/car/plr/ai/RFP settings.

Biggest thing still unclear if FFB drop is track dependent. A lot to test.

 

[Shovas]

To be clear I am leaning towards modulating the entire steering force, not RFP FGE alone. I am going to check how FGE affects FFB in rain but in my experience entire steering force drops and I want simplest and most logically comprehensible solution rather going down the fight with infinine combination of track/car/plr/ai/RFP settings.

Biggest thing still unclear if FFB drop is track dependent. A lot to test.

Ah, ok, updated to reflect my recommendation based on the uncertainty between wet and dry working optimally with only a single set of parameters.

If modulating strength could make it feel better than it's worth an experiment.

 

[IMC '67]

Do you remember if drop in FFB steering force is related to track wetness, like 20%/50%100% do they drop force increasingly?

I did some testing and would say that the drop amount in steering force is equal over the scale for every 10% increment of rain.