How works the accuracy system in Empire: Total War

[p.jakub88]

I. Introduction.

I gathered all the informations, that i know about the accuracy factor in land and naval battles.

I would like to write a tutorial about the basics and some of the advanced aspects of accuracy in Empire: Total War.

Credits goes to Kaunitz for his accuracy test and research.

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II. Accuracy overview.

Every unit in Empire: Total War has its own accuracy level.

If you "mouse cursor over" unit card, you will see the unit accuracy level.

The unit is less accurate in battle when it is tired, or use old type of musket (misslock).

In example: most of line infantry have accuracy 45.

The unit become more accurate when it gains experience.

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III. Accuracy mechanics.

The accuracy system is controlled mostly from kv_rules db table.

You could affect the unit accuracy, without changing its default overall accuracy level in units_stats_land.

The accuracy is of course smaller, when shooting from certain distance.

Shooting from max distance will inflicts few or no casualties in enemy lines.

ETW infantry units, have the tendency to shot above the enemy heads (yes, they are aiming too high).

But if you place on the battlefield two units (one friendly and one enemy), and they will be stationary all the time, in constant distant, in flat terrain - the results of musket fire will be the same.

Of course, if the terrain is not completely flat (contains of hills ,etc) there could be a small difference between your unit casualties and enemy casualties.

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IV. Modding accuracy.

In order to modify the accuracy mechanism, you will need to open and edit the kv_rules table (or with Pack File Manager or with DB Editor).

Not all entries all "well known", but some of them all quite obvious.

Changing the "projectile calibration" (the is not the exactly line name) you will make stronger effect of unit overall accuracy (default value for projectile calibration is 1).

Changing the "distance_to_half_chance_hit" will make the unit more accurate when distant or less.

If you put i.e 20 (default value is 70), there will be no difference between very accurate unit and the low accurate unit when firing from max distance.

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V. Summary.

If i made any errors, or i missed some very important or basic informations about accuracy, please correct me as soon as possible.

I simply gathered all the info about the accuracy system, credits goes to Kaunitz for his help in modding accuracy.

Note: i 'm open to "constructive criticism", ideas and proposals --> but not for complaining.

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[Kaunitz]

Hey, I really didn't mean to offend you in any way!

May I add some additions and some questions for further research (well, practically everything I state or rather gather together from more experienced modders somewhere in the modding section needs further research and thus is not really fit for a tutorial imho):

• According to my experience, the "projectile calibration target area" affects the size of the area that units use for aiming. E.g. if you set it very high, you will see bullets fly almost vertically into the sky or directly hit the ground at just a few metres distance from the muzzle. Neither do I know if it is the "hit-area" or the "miss-area" which is affected, or both - i.e. do also bullets which are considered to hit the target disperse that much, or only those which are considered to miss the target? This question requires another question: do the shots (misses and hits) disperse in a totally random way? Id est: Does the game only know "hit" and "miss" (two absolute categories), or does it calculate how close to the centre of the target area an individual bullet hits (relative)? Apart from that, we'd need to try out how changing the calibration target area affects units' accuracy (does a units' accuracy stat still matter when you set a very high value?).
• The effect of fatigue on accuracy can be altered in the fatigue_effects_tables. I guess that, since it is measured in %, a unit with a higher accuracy suffers more from fatigue than units with lower accuracy. But of course I could be wrong.
• I think it's important to add that the overall effect of musketry is not only determined by accuracy, but also by damage (and of course reloading skill and misfires), which is not part of this tutorial. I find it quite hard to balance small arm impact by altering accuracy only. It can be calibrated much better in combination with damage (especially the projectile_damage_distance_multiplier in kv_rules, plus the type of weapon (ap/effective range based) in projectiles_table). But then it has to be remembered: If you weaken the importance of accuracy in favour of damage, the effect of fatigue is reduced as well.

[p.jakub88]

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Of course, that you could add some additions or ask questions!

I 'm glad, that you are interested in the accuracy and morale topic Kaunitz!

I really appreciate your help!

Yes, you are right: this tutorial isn't complex (i mentioned only some aspects of accuracy), so it needs further research and develop.

By the way, you could vote in my poll Kaunitz - if you wish so of course.

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[p.jakub88]

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5 minutes ago, i played a land battle in Alpine Pass against the Spanish line infantry in the early period.

How big i was surprised, when i saw that shooting at max distance makes 99% of bullets flying in the air!

The musket behavior in this case, is like shooting the canister shot ammo from 12 lbs cannon...

The units are aiming too high (artillery probably too), so the musket volleys are almost ineffective at max range (the spread of musket bullets is also big).

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[p.jakub88]

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I. The musket fire accuracy test.

Note: I' m using the "new ranges for units mod".

Battlefield: Alpine Pass, almost flat battle terrain

Distance between units: 250 meters

Unit size: 2 x 160 men (both sides counted together)

Sides: United Provinces vs. Spain

Experience: none

Morale: confident

Fatigue: Fresh

Time period: Early

Weather: Dry

Difficulty: Normal

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II. The effects of musket fire at max distance (=250 m).

When:

1) Calibration is 35, ca. 3 casualties from few volleys

2) Calibration is 20, ca. 6 casualties from few volleys

3) Calibration is 1 (default), ca. 20 casualties from few volleys (almost horizontal aiming).

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III. The effects of musket fire at medium distance (from 100 to 200 m).

When:

1) Calibration is 35, ca. 6 casualties from few volleys

2) Calibration is 20, ca. 12 casualties from few volleys

3) Calibration is 1 (default), more than 20 casualties from few volleys

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IV. The effects of musket fire at small distance (below 100 m).

When:

1) Calibration is 35, ca. 8 - 10 casualties from few volleys

2) Calibration is 20, ca. 15 - 20 casualties from few volleys

3) Calibration is 1 (default), more than 25 casualties from few volleys

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V. Summary and conclusions.

I think that "projectile calibration" value from: 20 to 35, is almost historical value for accuracy from XVIII century.

My line infantry unit was fresh all the time when shooting and was defending the position during the battle.

Giving too high calibration value, forces the infantry to aim higher (higher degree of fire).

So, value 1 means almost 0 degree when shooting.

In default Empire: Total War, infantry units were aiming almost directly into the enemy unit, so there was more casualties in land battle.

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[p.jakub88]

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Land artillery tests.

This time, i made two field artillery tests: one test with 12 lbs cannon foot battery, and the second test with 12 lbs mortar artillery.

Note:

I 'm using the "new ranges for units mod" and i changed the damage from cannon projectile (i doubled the impact damage for round shot in projectiles_tables).

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I. Test number 1 --> 12 lbs foot cannon.


1) Battle settings

Battle terrain: Alpine Pass, almost flat terrain.

Early period and weather dry.

Enemy unit: Spanish pikemen (160 men)

Experience: none (both units)

Morale: confident

Fatigue: Fresh

Battle difficulty: Normal

Distance between units: ca. 900m


2) Kv_rules settings:

---> artillery calibration 25 (50 is default)

---> distance to half chance hit 100 (default 70)


3) Enemy casualties:

---> max distance (up to 1200 m): ca. 6 casualties

---> medium distance (from 300 to 900): ca. 10 casualties

---> small distance (from 0 to 300 m): ca. 20 casualties

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II. Test number 2 --> 12 lbs mortar


1) Battle settings

The same as in test number 1

Distance between units: ca. 900m

Unit stats the same as in test number 1.


2) Kv_rules settings

The same as in test number 1.


3) Enemy casualties (i used the explosive shell only):

---> max distance (up to 1000 m): ca. 10 casualties

---> medium distance (from 300 to 900 m): ca. 15 casualties

---> small distance (from 0 to 300 m) ca. from 20 to 40 casualties

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III. Summary and conclusions.

My artillery batteries were stationary all the time and enemy pikemen unit was marching into my position (walking 99% of the time).

As you could see, the explosive shell is more "deadly" than cannon round shot in Empire: Total War.

The deadliest ammo type is of course canister shot: at close range (from 0 to 150 m), ca. 40 or more casualties (unit of 160 men).

The artillery as default aims too high in ETW land battles (i' m not telling about mortars, because it is normal...).

Calibration value for artillery, from 25 to 50 - seems to be nearly historical accurate and realistic.

The battle terrain is very important too - for the cannon accuracy.

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[Snuffythe3rd]

I've found this thread really interesting. In order to completely understand accuracy, I think it would best to find the equation that uses these variables in order to determine hit or miss. Do you know what file the algorithms would be in?

Also, when speaking about ap vs. effective range, what does ap stand for? What's the main difference? I'm assuming effective range uses limits to determine the accuracy "zone"; like

If x is defined as distance.
60>x>100
Would everything within these limits have the same accuracy?


Can accuracy be determined by a continuous function of distance?

Ex. Accuracy=40/x

In this case accuracy would be calculated at each distance. I'm hoping this is possible.


I could be completely wrong about this btw. Please let me know if this is true or not.

[p.jakub88]

Unfortunately, this topic if far more complicated that some people think (including me...). Nowadays i hardly ever play ETW, so i didn't find out any additional informations about how accuracy works. You could possible ask Kaunitz for more. Morale system is for me much more easier to understand to be honest..

[Freelancer Tex]

How does exactly work the "distance_to_half_chance_hit"? If higher,does it increases the chance to hit something at long distance? Or that value indicates the max distance which the projectiles are accurate?