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[DiRT 4] Constructive feedback on the subject of car-feel and physics: The Ultimate Thread

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chukonu said:

To me, Sam's video was VERY enlightening. 
Indeed, it was; it shows that the car behaviour is D4 is very realistic. 

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Um, where's Headlong gone to??.. (Body is 8 characters too short)
Right now he's sitting on his couch, chilling with a beer in his hand, while periodically convulsing with laughter when reading the nonsense being posted here. 

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Um, where's Headlong gone to??.. (Body is 8 characters too short)
Back to his puddle of negativitiy hopefully
No doubt, but I'm getting all of these email notifications that he's posting in this thread, but I'm not seeing them?  I wonder if he's been blocked??

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Um, where's Headlong gone to??.. (Body is 8 characters too short)
Back to his puddle of negativitiy hopefully
No doubt, but I'm getting all of these email notifications that he's posting in this thread, but I'm not seeing them?  I wonder if he's been blocked??
That explains the nonsense being posted here. 

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Um, where's Headlong gone to??.. (Body is 8 characters too short)
Back to his puddle of negativitiy hopefully
No doubt, but I'm getting all of these email notifications that he's posting in this thread, but I'm not seeing them?  I wonder if he's been blocked??
Wow, you're right. I'm getting them aswell since I'm the thread owner.
That's not right, he should be unblocked.

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Um, where's Headlong gone to??.. (Body is 8 characters too short)
Back to his puddle of negativitiy hopefully
No doubt, but I'm getting all of these email notifications that he's posting in this thread, but I'm not seeing them?  I wonder if he's been blocked??
Yeah I'm seeing that as well. Maybe the mods have struck with great vengeance and furious anger!

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Headbong said that RX is no different from rally despite RX not suffering from all the issues we are discussing. Also he didn't see anything wrong with braking distances. He also insisted that heavy truck's brake distances are shorter than light car's, and that Mk II is behaving realistic in D4. On top of other remarks. Plus he was offensive toward everyone trying to reason with him. At one point everyone was wasting time trying to prove him wrong while all he cared for was calling names. I think now that he is gone we can finally have some constructive feedback going on :) 

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SamRWD said:
Headbong said that RX is no different from rally despite RX not suffering from all the issues we are discussing. Also he didn't see anything wrong with braking distances. He also insisted that heavy truck's brake distances are shorter than light car's, and that Mk II is behaving realistic in D4. On top of other remarks. Plus he was offensive toward everyone trying to reason with him. At one point everyone was wasting time trying to prove him wrong while all he cared for was calling names. I think now that he is gone we can finally have some constructive feedback going on :) 
LOL @ Head'bong', well he's certainly ticked someone off with admin power haha.  @SamRWD I just did 5 stages in Sweden in a Fiesta R5...wasn't that bad, but you what is a little startling, is the bumpy roads in Sweden?!?  Not used to it....Sweden has always been more flowy in previous titles I thought (sorry a little off-topic).  But yeah, I didn't mind the braking accuracy...especially down hill.  Had to plan my breaking points and scandinavian flicks accordingly.  Mmmm

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Yes downhill braking is much better, I remember doing wet Spain in Ford 2007 and I really needed to pay attention to pacenotes on downhill sections. It felt really immersive! 
Overall in game Sweden is more similar to recent events surface, last time it was almost canceled due to poor road conditions and lack of snow altogether. I finished career event recently and I remember very clearly that you could underbrake and enter the corner a bit too fast because cars were slowed down easily using tyre friction on slide. Otherwise corners could be navigated with next to no grip loose. I already stated that all world record videos show how that's the quickest way to drive in D4 - you can drive most corners with next to no grip loose while in real life if you went with this high speed inertia would throw the car outside of the corner m

I wish we could get one car with beta physics parameters for evaluation testing, then other cars could be addressed based on that single car fix. Getting whole fleet fixed at once is a big task and needs to be done carefully IMHO. 

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fab1701 said:
SamRWD said:

We could brainstorm if it is not a matter of lack of engine power, however that wouldn't explain too short braking distances.
That one just got me thinking...

Well let's pretend the grip gets lowered. This would help with the rear and the braking distance on gravel would increase. But then, because of less grip, the forward thrust would decrease even more. Now this seems wrong to me.
But there is a difference between braking and accelerating on gravel: Thrown material. Does anybody know how much thrust is created by simply the dirt that gets thrown away by a spinning tire? I bet this can be calculated to a degree. Also, how easy is it that a dirt-pile simply gets shredded away? Maybe thats something that needs to be considered.
EDIT: well i guess the extra-thrust will be minimal, but the tires digging in the ground should find additional grip somewhere down there ;).
That's actually really good point I missed so far. Acceleration is less effective because of that in real life indeed! 

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If the car parameters are correct then by adjusting the surfaces the game will just become more realistic. If the cars are not made by actual values but by guesswork to get the end result seem realistic, then the end result might be unrealistic.

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Um, where's Headlong gone to??.. (Body is 8 characters too short)
Back to his puddle of negativitiy hopefully
No doubt, but I'm getting all of these email notifications that he's posting in this thread, but I'm not seeing them?  I wonder if he's been blocked??
As far as I know he's been blocked so he can post but no one can see it.  All my posts are getting disagreed with by him so we know he's still up above judging us from his cloud of delusion.

Anyways, really hope we get a road book today and they address some of these issues with D4 in it.

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thats what i doubt that theyre correct ^ ......................i had to do some crazy stuff to the 306 to get it to understeer and act like a FWD high powered car on tarmac.
Then it did some funky stuff in mid turns when pushed hard ,at the limit.

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"That said, a good number of us have stuck around to make sure that we are listening to your feedback and working out where we go next. We are seeing some recurring themes out there, so rest assured we are looking to address things in a priority order. Stuff that will come through relatively quickly will be based on fixing stability issues but once we have sorted those we will be looking to get some more cool and exciting elements into the game."
Quote from Christina at CM,from last road book.Can anyone guess what new elements she may be about?


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hawku0 said:

In Dirt 4 it seems that there are same friction values in every situation or the difference is very minimal. That leads to that the friction values have to be higher to car to feel stable when tires aren't slipping, but it causes problems when the tires are slipping.
Hm. I don't think that this is the case in D4. I believe having a uniform friction level would lead to a higher consistency and that seems not to be the case, considering that the same car can get straighten out by resistance to the rear and suddenly spin around 270° on the same stage. To me this seems like the simulation actually is way more complex than even two different friction levels, but maybe the way all of this plays together leads to some issues. After all, even though the braking distances seem to be nearly the same on different surfaces, the handling itself sure isn't.

Also regarding braking distances: I just recently logged some telemetry data, to figure out some exact values. The Subaru Impreza 2001 with default settings for example brakes at DirtFish from 100km/h to 0km/h in under 1.5s and with a braking distance of around 33m (measured from position-data) on nearly all surfaces alike. The longitudinal g-force is around 1.4g. On tarmac this doesn't seem too far off from RL to me, considering this is a rally car with really great tires and suspension. On gravel though... :/
But a surface being defined as 'gravel' doesn't necessarily indicate longer braking distances. Take a surface that is really hard and has some sort of round gravel stones on it. This should be like braking on marbles with a really long braking distance as a result of this. Now on the contrary take a surface that has even more gravel on top of it, or a really soft bed. This can stop a car way quicker than any tarmac, simply because the tires get buried in the surface. The question should be, which sort of surface is beeing represented here?

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Well, after almost finishing the modern championship in sim mode I came to the conclusion that this  game is more fun when playing with a gamepad and it was built for that. Driving with a wheel car feels slugish and difficult to throw arround, maybe some wheel settings adjustment could help. idk

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^ then its not a sim ...............i havent tried with a PS4 pad,but after reading all this i will!

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fab1701 said:
hawku0 said:

In Dirt 4 it seems that there are same friction values in every situation or the difference is very minimal. That leads to that the friction values have to be higher to car to feel stable when tires aren't slipping, but it causes problems when the tires are slipping.
Hm. I don't think that this is the case in D4. I believe having a uniform friction level would lead to a higher consistency and that seems not to be the case, considering that the same car can get straighten out by resistance to the rear and suddenly spin around 270° on the same stage. To me this seems like the simulation actually is way more complex than even two different friction levels, but maybe the way all of this plays together leads to some issues. After all, even though the braking distances seem to be nearly the same on different surfaces, the handling itself sure isn't.

Also regarding braking distances: I just recently logged some telemetry data, to figure out some exact values. The Subaru Impreza 2001 with default settings for example brakes at DirtFish from 100km/h to 0km/h in under 1.5s and with a braking distance of around 33m (measured from position-data) on nearly all surfaces alike. The longitudinal g-force is around 1.4g. On tarmac this doesn't seem too far off from RL to me, considering this is a rally car with really great tires and suspension. On gravel though... :/
But a surface being defined as 'gravel' doesn't necessarily indicate longer braking distances. Take a surface that is really hard and has some sort of round gravel stones on it. This should be like braking on marbles with a really long braking distance as a result of this. Now on the contrary take a surface that has even more gravel on top of it, or a really soft bed. This can stop a car way quicker than any tarmac, simply because the tires get buried in the surface. The question should be, which sort of surface is beeing represented here?
Yes, the uniform friction level should lead to higher consistency, but to me it seems that the suspension can't handle the tire forces and that causes the inconsistency. I have noticed that the unexpected spinning usually happens when there is a large spike in the suspension forces.
Maybe I have to do more testing and record more telemetry data.

To me this seems like the simulation actually is way more complex than even two different friction levels
Yes, the simulation is way more complex than that. I am just talking about difference between static and kinetic friction to simplify the point . Of course there are multiple different curves and parameters to determine what the friction should be at any point in time. There is a list of some parameters what are used in most tire models:
http://www.edy.es/dev/docs/pacejka-94-parameters-explained-a-comprehensive-guide/

In that guide you can see some pictures of tire friction curves and to me it seems that the the longitudinal force curve in Dirt 4 doesn't drop very much after the peak value. That might be a correct curve in some cases, but i would say that the curve should not be the same on every surface.
Some of the parameters used in tire force curves are possible to get from a tire manufacturer and that might have been the case with the Dirt 4's RX tires on tarmac.

On top of those tire force curves the Codemasters would have had to implement the tires digging to ground calculation, which would need multiple different parameters to get a realistic result. Implementation or parameters of that calculation might be the cause for the short braking distance on gravel and not just a one parameter in the longitudinal force calculation.

Of course everything could have just been calculated with bogus values. It isn't exactly easy to reverse engineer the exact parameters out from the limited telemetry data, but those are my thoughts on this problem.

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Was wonderig if the tire data could have been used on tarmac tires for rally too?from Rally X that is 

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Was wonderig if the tire data could have been used on tarmac tires for rally too?from Rally X that is 
Nope, completely different type of tyres. 
RX are short races, in rally they have soft/hard compound to choose. And thats something KickUp said is a thing for a future. 

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versedi said:
Was wonderig if the tire data could have been used on tarmac tires for rally too?from Rally X that is 
Nope, completely different type of tyres. 
RX are short races, in rally they have soft/hard compound to choose. And thats something KickUp said is a thing for a future. 
im with you but if the RallyX tire model is replantable to rally and that much more sophisticated then why not use it.And yes i totally understand theyre different spec:) Although why we cant get tire choices for a sim in which cars rely on them exclusively for in teal life,is beyond me.
So since there isn t a choice,and RallyX tire model is that much better,then we should use that:)

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Not to stray too far off topic, but I really expected to see Tire choice play a part in the tuning menu. Speaking strictly from the RX side of things, wet or dry, new or used and where to put them on the car. The teams are allowed 8 tires of wet and 8 tires of dry per championship weekend (event). I wonder why it's not even mentioned in the Tuning menus? Tire pressure is another one I expected to see. Maybe those choices would add too many variables to the calculations?

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^ ESPECIALLY when its the number one items the crews and drivers mention as having big influence on stage times 

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