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S6R2: Silverstone International Post-Race Chat

Author Topic: S6R2: Silverstone International Post-Race Chat  (Read 8834 times)

Online Bird

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #30 on: April 01, 2015, 06:47:50 PM »
And this accident has made me realise how different it looks from each car - even with good pings.  In my replay the overlap is barely any.  On Marty's it's nearly half a car.  Altho I dunno how do you get the overhead view, I've been watching from my car. How do you do that, Marty?

Offline Matthew111

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #31 on: April 01, 2015, 07:24:58 PM »
First off sorry Perch for the warpy internet moment, it was my pc as my net dropped after that race and in race 3 it was all over the place! Bit of a shame was a good battle for the podium. I was on TS but i dont think my mic worked

Race1: Got a solid 4th was just managing the gap to stan all the way home couldnt touch the alfas in the race.

Race2: Did the lap of the gods in qualy to steal a pole position off those pesky alfas haha was one of the best qualy laps i have done i think, pitty it was probably the most useless too as those alfas off the line sent me straight back to 4th lol. Was on 3rd for a bit and had perch catching me as my tyres faded, I tried to keep him behind me in the dieing laps but then had that net issue and it sent us both off sadly so i finished 6th.

Race3: My net died after race 2 and by the time i rebooted everything i joined 1 lap down so just circulated for points with my warpy net lol

do you even motorsports?

Online Gratulin

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #32 on: April 01, 2015, 07:48:32 PM »

And this accident has made me realise how different it looks from each car - even with good pings.  In my replay the overlap is barely any.  On Marty's it's nearly half a car.  Altho I dunno how do you get the overhead view, I've been watching from my car. How do you do that, Marty?
My view is that there is some sort of programming error in AC with perspective that leads to this problem. I got caught with this problem in a Mini race where I was the inside car. The view from each car w.r.t overlap was totally different.

Hence Helicorsa is essential IMHO. Since I have started using it I only run into the back of people :))

Online Bird

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #33 on: April 01, 2015, 08:38:12 PM »
It's not a perspective error IMO.  Latency + the program actually needs to do some computing, even if it's very quick.

See, if we both have 50ms latency to the server, that means 100ms all up as the info travels Ysu-Server-Martin.  Just that, 0.1 second.   
Now, at 20m/s speed (which is 72km/h) will lead to a 2m offset between car positions.   Half the lag, 25ms each, would mean 1m offset.   And I have not allowed for computing at all, nor frame lag (video cards often pre-calculate frames), nothing.

So as you see the program actually have to compensate for lag all the time somehow - probably with prediction...and maybe that's where problems lie.

I'd like to know how they deal with it, it's an interesting problem. :)

Offline Vipergod

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #34 on: April 01, 2015, 08:41:13 PM »
Three awsome races for me
R1 Had a massive battle with Bird for most of the race Till i hit that stupid ripple strip on the last corner
R2 Rolz behind & Freezer in front Epic racing, Loved it
R3 Hooked up well in qualy, Started and finished 2nd, No way could i get near Perch

Thanks for the thumbs up Wobbly,  I used to win a few in Netkar, Just not good enough at this game yet

Offline marty

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #35 on: April 02, 2015, 12:29:40 AM »
And this accident has made me realise how different it looks from each car - even with good pings.  In my replay the overlap is barely any.  On Marty's it's nearly half a car.  Altho I dunno how do you get the overhead view, I've been watching from my car. How do you do that, Marty?

For overhead I use the F5 camera, this is a camera fixed to the car but you can move it anywhere you want. I find its the best way to check as perspective from cars may always be a little deceptive. To use this camera you need to first make a basic edit to one of the ini files. camera_onboard_free.ini which is found in Program Files (x86)\Steam\steamapps\common\assettocorsa\system\cfg

You just need to edit this line
SPHERICAL_COORDS=1
make this 0 to unlock the camera as otherwise its locked to the car, once unlocked you can use keys ASDFGWEZXC etc to move it around and when you press play it will stay locked to the car in that position, you can also adjust fov(zoom) with + - keys

Regarding lag I dont think it would be so much but an easy way to compare and test the lag is if you upload your replay file then I could record both videos side by side and compare them to see if there is noticeable lag between what 2 people see. I doubt with 40ms pings the difference would be more then a cm in spacing of the cars but it would be interesting to see still.
« Last Edit: April 02, 2015, 12:32:31 AM by marty »

Online Bird

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #36 on: April 02, 2015, 12:15:10 PM »
Thanks for the info!
I'll edit my replay when I get some time, it's too big for upload as it is :)

The lag is what it is; it exists as a matter of fact, and I've just calculated the impact above.
The "how does the program deal with it" is the big question IMO.

Online Bird

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Offline marty

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #38 on: April 02, 2015, 01:35:00 PM »
With the replay if you could do from start of race to just after the contact. Easiest way for me to try sync footage is from the race start if the start isnt there its not so easy to do this. I can sync back from the point of contact but race start would be interesting just to see how other cars are seen to 2 people and if its a very noticeable difference.

It would be interesting to use the same camera angle and overlay the 2 replays fading one video into the other. This will show how much effect lag has, I dont think its going to be very noticeable. The actual lag would just be pretty much both pings added together (however I may be wrong it seems the way it would be) at the most so maybe 80ms between us. That is .080 of a second difference which at the speed we were traveling at shouldnt be a very significant amount.

Offline marty

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #39 on: April 02, 2015, 01:41:59 PM »
It's not a perspective error IMO.  Latency + the program actually needs to do some computing, even if it's very quick.

See, if we both have 50ms latency to the server, that means 100ms all up as the info travels Ysu-Server-Martin.  Just that, 0.1 second.   
Now, at 20m/s speed (which is 72km/h) will lead to a 2m offset between car positions.   Half the lag, 25ms each, would mean 1m offset.   And I have not allowed for computing at all, nor frame lag (video cards often pre-calculate frames), nothing.

So as you see the program actually have to compensate for lag all the time somehow - probably with prediction...and maybe that's where problems lie.

I'd like to know how they deal with it, it's an interesting problem. :)

I hadnt seen this post before, the thing is the replay will just show how the game will display gaps to cars. Add to this input lag and how long it takes for you to actually see what the computer has rendered which is another factor. But what the replays show should be how both see it at the time and display lag will just delay your reaction time to what your seeing on screen. The replays compared against each other will show how the game deals with lag with predictive netcode. After all its only getting data at the server hz setting.

I am not sure what Wally has the server set at, probably 20hz would be my guess so at 60 fps its only getting car location data every 4th frame and needs to guess/predict the others. Add to this all the different types of lag and its amazing you can race door to door even amongst local guys let alone across the world with 200ms or higher pings.

Online Bird

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #40 on: April 02, 2015, 02:32:58 PM »
here's the cut from start
https://dl.dropboxusercontent.com/u/24242159/ac/ferrari_f40_silverstone-international-accident.zip

Btw, here it is from my viewpoint, just when the braking starts.  Huge difference - as expected.


Online Wally

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #41 on: April 02, 2015, 02:50:52 PM »
15 Hz.
“You can please some of the people all of the time, you can please all of the people some of the time, but you can’t please all of the people all of the time”

Online Gratulin

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S6R2: Silverstone International Post-Race Chat
« Reply #42 on: April 02, 2015, 02:54:22 PM »
here's the cut from start
https://dl.dropboxusercontent.com/u/24242159/ac/ferrari_f40_silverstone-international-accident.zip

Btw, here it is from my viewpoint, just when the braking starts.  Huge difference - as expected.


The key views are the views from each car. Compare those with this one and you will see the perspective difference between each of the three views. Hence AC has one set of position data in Bird's replay but then presents the relative position view differently to each car.

A bug in my opinion.

Offline Wobblyone

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #43 on: April 02, 2015, 03:09:33 PM »
Brilliant so every time I T bone someone now....I can say its a bug, programming error?  Happy days gents....happy days ;)

Online Bird

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Re: S6R2: Silverstone International Post-Race Chat
« Reply #44 on: April 02, 2015, 03:54:42 PM »
Brilliant so every time I T bone someone now....I can say its a bug, programming error?  Happy days gents....happy days ;)
Glad to be of service!