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admiral_noone

How are dispersion rolls calculated?

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So I heard about the dispersion woes of the French BBs, especially Gascogne and France, as well as Roma, and it got me wondering since I'm not THAT quick to joining the complain train; what gives with that? I know that they use German dispersion patterns, their sigma is mostly sub-2.0 except France, and their shells were very fast which amplifies the effect of the vertical dispersion plane from your viewpoint (therefore making sigma more drastic). That seemed fine and dandy of an explanation in my book until I saw Notser's video on Gascogne's identity had a comment which said dispersion rolls are done per-turret rather than per-shell, meaning that if a turret gets a bad roll all its shells will be all over the place, which is detrimental to Richelieu/Gascogne with 2 turrets (all or nothing RNG basically) compared to Bismarck with 4. But I'm not really sure if that's true, because if it is that would actually explain quite a bit about the french quad turret dispersion, as well as Roma's to a lesser extent.

 

Yes, I was prompted by a Youtube comment, which is why I asked here because I don't know for sure.

Edited by admiral_noone

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16 minutes ago, admiral_noone said:

So I heard about the dispersion woes of the French BBs, especially Gascogne and France, as well as Roma, and it got me wondering since I'm not THAT quick to joining the complain train; what gives with that? I know that they use German dispersion patterns, their sigma is mostly sub-2.0 except France, and their shells were very fast which amplifies the effect of the vertical dispersion plane from your viewpoint (therefore making sigma more drastic). That seemed fine and dandy of an explanation in my book until I saw Notser's video on Gascogne's identity had a comment which said dispersion rolls are done per-turret rather than per-shell, meaning that if a turret gets a bad roll all its shells will be all over the place, which is detrimental to Richelieu/Gascogne with 2 turrets (all or nothing RNG basically) compared to Bismarck with 4. But I'm not really sure if that's true, because if it is that would actually explain quite a bit about the french quad turret dispersion, as well as Roma's to a lesser extent.

 

Yes, I was prompted by a Youtube comment, which is why I asked here because I don't know for sure.

 

Hey Admiral - Here's a link from iChase who recently put up a video explaining the components of your shell accuracy (Horizontal/Vertical Dispersion, Sigma)

[ Link from iChaseGaming ] Captains Academy #41 - Definitive Guide to Dispersion

iChase provides a detailed explaination of the differences between Horizontal and Vertical dispersion and Sigma and how this affects your aim and shell hit results.  Understanding this clearly will help you get more hits on your intended targets on your target ship.

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In short:

A ship has a vertical dispersion, a horizontal one and a sigma value. Vertical dispersion is a function of range and shell velocity and isn't listed in game.

The two dispersion values form an ellipse and the sigma decides the dispersion within that ellipse, the higher the sigma the more the shells tend towards the center.

That said, people on this forum tend to overestimate the importance of sigma, often citing a .1 sigma difference as being really important. In reality, a .1 sigma difference is at most a few % and tends to show itself only over several hundred shells fired.

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18 minutes ago, Lert said:

In short:

A ship has a vertical dispersion, a horizontal one and a sigma value. Horizontal dispersion is a function of range and shell velocity and isn't listed in game.

The two dispersion values form an ellipse and the sigma decides the dispersion within that ellipse, the higher the sigma the more the shells tend towards the center.

That said, people on this forum tend to overestimate the importance of sigma, often citing a .1 sigma difference as being really important. In reality, a .1 sigma difference tends to show itself only over several hundred shells fired.

Lert, you got it reversed. Horizontal at max range is shown in game, and is linear with range. Vertical dispersion isn't shown in game, and is a function of range and shell velocity.

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1 minute ago, SgtBeltfed said:

Lert, you got it reversed.

So I did. I amended my post. Thanks for pointing it out!

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I have the basics down, thank you; what I’m not sure is if, say, a bad roll that lowers the odds of a shell going where you aim occurs, is it applied to every shell from that turret, or does each shell get their own roll so a bad roll on one shell doesn’t affect other shell rolls?

Also the comment said: “The problem on the French BBs is the fact that quad turrets in few numbers give you less dice rolls in dispersion. If only WG could implement the real layout of the quad turrets (two twin turrets together with an armored bulkhead in between) it would make things so much easier because on Dunkerque, Richelieu, Gascogne or France, you'd have 4 dispersion rolls instead of 2. 2 rolls is all or nothing basically. Where Bismarck has 4 rolls and Fuso has 6.”

A response to my skepticism: “no dispersion is calculated per turret. So on a quad turret, all 4 shells will have good, mediocre or awful dispersion. Sometimes 2 shells happen to group anyway”

Hope that clears things up. 

Edited by admiral_noone

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21 minutes ago, admiral_noone said:

I have the basics down, thank you; what I’m not sure is if, say, a bad roll that lowers the odds of a shell going where you aim occurs, is it applied to every shell from that turret, or does each shell get their own roll so a bad roll on one shell doesn’t affect other shell rolls?

I - .......... honestly don't know. I always figured it's per shell, but I've never scienced it and I wouldn't even know how.

@LittleWhiteMouse, do you have any insight into this?

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I seem to recall one of the WG types saying it was per shell and not per salvo. 

Edited by JCC45

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35 minutes ago, admiral_noone said:

I have the basics down, thank you; what I’m not sure is if, say, a bad roll that lowers the odds of a shell going where you aim occurs, is it applied to every shell from that turret, or does each shell get their own roll so a bad roll on one shell doesn’t affect other shell rolls?

Dispersion rolls are calculated independently per shell. You can see that, especially at low tier BB where shells from the same turret can have wildly different dispersion rolls. 

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I'm pretty sure it's per shell. The only thing with some of the French battleships that might be odd is getting into brawls with widely spaced turrets. If your front turret is pointed 90 degrees to the target, the aft turret might be at a 60 degree angle, with the smaller guns, you will still hit, but might bounce. I see this with Graf Spee against Battleships when things have gone horribly wrong, and with Mikasa when things have gone hilariously right.

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2 hours ago, Fog_Battleship_NCarolina said:

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Yup! If you pull a good accurate lead where the shots will hit, the shells disperse all around the target. If you pull a poor lead and it's a clear miss, the shell pattern will be tight. I see this a lot, especially with Dunkerque.

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It is per shell.  People like to think it's per turret because they'll see a wonky spray of shells and attribute it to one roll of bad luck.  Having mapped (literally) thousands of shells, I can say for certain:  Each gun has its dispersion calculated separately.

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