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## How Negative Model of Spread works (Accuracy)

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Monday, November 7th 2016, 10:52pm

### Quoted from "leptis"

This is because the spread is improving during the burst but the cumulative effect of the Horizontal Recoil compensates that resulting in a distribution almost equal with a very slight tendency to worsen from bullet 7-8th (due to constant spread and cumulative effect of the Horizontal Recoil).
So this is the key point, here.

The data is very convincing, but this effect of "cumulative recoil" just doesn't make much logical sense to me: how can horizontal recoil be cumulative? Can you try to explain it in layman's terms?

I explained that in the threads:

Horizontal Recoil DOESN'T produce an uniform distribution of hits.

and

Position, shape and frequency distribution in a burst

But OK. In layman's terms.

Remember that we are speaking of probability not about an individual burst where the path of the barrel will seem erratic.

In the firts bullet Recoil H can move your aiming point to left or to right. The maximun width will be betwen MaxLeft and MaxRight with an uniform probability to be at any point between those limits.

In the second shot, if the first one has put your weapon on the extreme right side, there is a possibility it goes to the extreme right again, but with a lower probability because two chained events (right-right) are required. Central values are more probable. Begins to draw a normal distribution (Gauss Bell) with more probability in the center than at the ends.

The maximum width of this bell in the second shot will be 2x(MaxLeft-MaxRight.)

This is the cumulative effect of Recoil H (in terms of probability). Distributions tend to be wider when more shots are fired.

Despite that most of the shots remain in a similar central zone.

This can be evaluated with some static parameters (such as the standard deviation), demonstrating that it doesn't grow as fast as the possible width of the distributions. In other words, 90% of the shots are in a similar area that grows more slowly than the width of the distribution.

It is because the extreme events right-right-right-right-right... are more improbable than the common right-left-right-left-right....

I don't know if it is clear enough.

This post has been edited 1 times, last edit by "leptis" (Nov 7th 2016, 10:57pm)

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Thursday, December 15th 2016, 1:09pm

Hi!

I made some crude and probably wrong negative spread calculations for some of the new patch LMG stats. Can anyone of the experts confirm or correct them?

Name ........................ Jump(1) ... Decrease/s(2) ... TTBS(3) ... BTBS(4)
M1909 Telescopic .......... 0,84 ...... -0,73/s ............ 0,96s ...... 8
BAR1918 Telescopic ....... 0,80 ...... -1,01/s ............ 0,63s ...... 7
Huot ......................... 0,72 ...... -0,83/s ............ 0,65s ...... 6
MG15 Low Weight ......... 1,08 ...... -0,83/s ............ 1,08s ...... 9
MG15 Suppressive ......... 1,26 ...... -0,71/s ............ 1,52s ...... 13
Lewis Gun Low Weight ... 1,05 ...... -0,82/s ............ 1,02s ...... 9
Lewis Gun Suppressive ... 1,26 ...... -0,68/s ............ 1,54s ...... 13
Madsen Low Weight ...... 0,96 ...... -0,95/s ............ 0,75s ...... 7

(RPM / 60) x Negative Spread Increase Per Shot

(RPM / 60) x TTBS, rounded up to whole number

The weapon that impressed me most from these numbers (if they're somewhat correct) is the Madsen. It's not much worse than its more accurate brother, the BAR but the extra 11 rounds should really help. Basically you should get an extra volley of shots out of it compared to the BAR, or, in other words, one more potential kill per mag. Actually it scales pretty accuratly in the "accuracy for magsize tradeoff" department.

This just comes from observing the numbers - I never actually tried the Madsen ingame (deemed too inaccurate) so maybe it's something entirely different in ingame conditions.

This post has been edited 3 times, last edit by "drdim" (Dec 15th 2016, 1:39pm)

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Thursday, December 15th 2016, 1:46pm

fssm=X shots to reach base spread
2nd shot(assume 5fssm) =5 shot positive spread

it's as simple as that, i think

i honestly can't remember how any bullets you have to add, but it's either 1 or 2.
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bf4
on 13/05/2016
23rd M320FB user on pc(13/05/16)
rush mode score RANK:2794 TOP:2% OUT OF:215398
obliteration mode scoreRANK:994 TOP:1% OUT OF:159466
handgun medals RANK:2236 TOP:2% OUT OF:143874
longest headshot RANK:9512 TOP:4% OUT OF:257589
recon score RANK:10871 TOP:4% OUT OF:274899
general score per minute RANK:10016 TOP:4% OUT OF:294774

bf3
31/3/2012 4:58:

Revives per assault minute RANK: 6019 TOP: 3%
Headshots / kill percentage RANK:25947 TOP:13%
MVP ribbons RANK:18824 TOP:11%

*= 6 if we not count the EOD BOT headshots

### Quoted from "CobaltRose"

@kataklism

ARGUMENT DESTROYED 100

ENEMY KILLED [REASON] JSLICE20 100

WRITING SPREE STOPPED 500

http://i.imgur.com/4X0321O.gif

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Thursday, December 15th 2016, 3:15pm

So the "Negative spread 'increase' per shot" value is derived from the fssm? (Or the other way around?)

This post has been edited 1 times, last edit by "drdim" (Dec 15th 2016, 3:28pm)

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Thursday, December 15th 2016, 3:29pm

rather the other way around, it's the fssm result that is given by negatively multiplicating the negative sips, resulting in a positive fssm and negative sips, and naturally if this multiplicator is a full number, then that means you can guess fairly easily how many bullets you'll need to reach base spread.
"I'm just a loot whore."

### stuff mostly unrelated to BF4 that interests nobody

bf4
on 13/05/2016
23rd M320FB user on pc(13/05/16)
rush mode score RANK:2794 TOP:2% OUT OF:215398
obliteration mode scoreRANK:994 TOP:1% OUT OF:159466
handgun medals RANK:2236 TOP:2% OUT OF:143874
longest headshot RANK:9512 TOP:4% OUT OF:257589
recon score RANK:10871 TOP:4% OUT OF:274899
general score per minute RANK:10016 TOP:4% OUT OF:294774

bf3
31/3/2012 4:58:

Revives per assault minute RANK: 6019 TOP: 3%
Headshots / kill percentage RANK:25947 TOP:13%
MVP ribbons RANK:18824 TOP:11%

*= 6 if we not count the EOD BOT headshots

### Quoted from "CobaltRose"

@kataklism

ARGUMENT DESTROYED 100

ENEMY KILLED [REASON] JSLICE20 100

WRITING SPREE STOPPED 500

http://i.imgur.com/4X0321O.gif

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Thursday, December 15th 2016, 4:04pm

So in other words:
2. shot = base spread + ffsm x |sips|
3. shot = (base spread + ffsm x |sips|) + sips <-- negative in case of LMG
4. shot = (base spread + ffsm x |sips|) + 2 x sips
...
X. shot = (base spread + ffsm x |sips|) + ffsm x sips
== base spread in case of LMG

I think I'll visualize this for every LMG later like the diagram on the first page but with RPM measured in, so most graphs should be different.

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Thursday, December 15th 2016, 7:10pm

### Quoted from "drdim"

I think I'll visualize this for every LMG later like the diagram on the first page but with RPM measured in, so most graphs should be different.

Perhaps this is you are looking for:

BTBS= Bullet that reaches base spread.

TTBS= Time to shot BTBS

(edited)

This post has been edited 1 times, last edit by "leptis" (Dec 15th 2016, 9:15pm)

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Thursday, December 15th 2016, 8:04pm

@leptis

For example, if we count the number of gaps (1-2, 2-3, 3-4, etc.) the BAR Telescopic reaches minspread after the sixth shot. Therefore, it should take 0.6s to reach minSpread. Shot 7 should not be counted because it is at minSpread.

The same logic applies to the BTBS column as well. The final bullet should not be counted because it has reached base spread at that point. The BAR took 6 shots to get the 7th at base spread. If you fire six shots but not the 7th it is still at base spread.
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### Quoted from "blahdy"

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Thursday, December 15th 2016, 9:12pm

### Quoted from "NoctyrneSAGA"

OOPS!!! You are right!!!

Sometimes I forget that firt bullet is not time-consuming. I added the last column too quickly.

If BTBS is the number of bullet that REACHES base spread the column BTBS would be correct .

TTBS has to be corrected for N-1 bullets (firts shot T=0).

I edit that.

Thanks!!!

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Friday, December 16th 2016, 12:43am

well. it's apparently quite hard to visualize that stuff - leptis did alot better than me...
here's my take on it anyway, which is, let's be frank, mess. At least I tried
EDIT: much improved version of this diagram on the next page

### Spoiler

edit: In case anyone is wondering: the descents of the graphs should be linear but they're not, because the timescale at the bottom isn't linear either. It's just certain milliseconds at which "stuff happens" lined up on a scale.
For some reason that was the only way I could persuade Google Sheets to display everything.

This post has been edited 3 times, last edit by "drdim" (Dec 16th 2016, 6:46pm)