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Xen0tech

Hiding in a bush vs AI

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Okay so I know the ai cant spot you if you are behind a bush but if i'm in a bush completely still will that help at all? So far not much luck trying to stealth the ai :( Anyone know a way to turn their detection down a bit? One thing I can't stand is how the ai can still aim while prone in high grass, I don't get it because I know for a fact grass can be used as concealment so how come it doesn't block their view? Its almost like once you have been detected they don't need a line of sight to aim at you.

Also does anyone know how darkness effects ai detection?

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If you are hidden behind a bush, the AI will locate the general position of where you are. If they don't know your exact location, but they know your general position, that alone is enough to get you killed.

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Okay so I know the ai cant spot you if you are behind a bush but if i'm in a bush completely still will that help at all?

That depends on what you're doing. The AI is able to predict where you'll be if they see you moving to the bush, and if you shoot from the bush they'll be able to guess where you are. The AI detects whether or not you're occluded by a bush using the geometry LOD of that object. That LOD looks quite different than the first resolution LOD that you're viewing, so it's difficult to tell how much you're actually concealed.

So far not much luck trying to stealth the ai :( Anyone know a way to turn their detection down a bit?

Try using the AI skill slider in the difficulty menu.

One thing I can't stand is how the ai can still aim while prone in high grass, I don't get it because I know for a fact grass can be used as concealment so how come it doesn't block their view?

Yeah, that's annoying (that they can shoot accurately while prone in tall grass). The AI uses a clutter simulation to factor into their ability to detect other units in grass, but I'm not sure if the same thing applies to if themselves, so I don't know if they are blinded by grass the same way we are.

Its almost like once you have been detected they don't need a line of sight to aim at you.

The thing about the AI is that once they detect you they will start to do recon by fire using predictive algorithms. If you're not moving dynamically, they will hit you.

It sounds like for the purposes of gameplay you're relying too much on concealment and not enough on cover.

Also does anyone know how darkness effects ai detection?

Darkness has a marked effect on AI detection unless they have night vision systems.

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Here's a REALLY good way to actually view how/when/where/and for how long the AI sees a player.

Originally Posted by MadDogX

The mission gives you visual feedback of the AIs knowledge of your position, directly from the nearTargets command. Try it out.

Once you have gained the AIs attention, you should see a white smoke particle surrounded by a red ring. This is the area where the AI actually thinks you are. After some testing with this, it is pretty clear to me that the AI does not have any kind of magical knowledge of the players location.

http://forums.bistudio.com/showpost.php?p=1525272

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I just spent about 15 minutes hiding under a pine tree surrounded by some scrubby bushes with an entire squad of keyed-up Russians crawling around less than 50m from me. I didn't dare move anything but my head while a friendly Su-25 flew passes overhead, chucking FFARs into the midst of us. Eventually I was able to crawl away. Bushes will save your life.

The huge problem the game has is that while bushes and trees occlude the AI's vision entirely, and the tall grass statistically impedes their detection, once you are spotted that grass will pretty much disappear from the equation. They will shoot through it as if it is transparent while it is making it impossible to return fire because of its height and density. At least in first person and without crosshairs.

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"It sounds like for the purposes of gameplay you're relying too much on concealment and not enough on cover. "

just a little addin here, the ai can shoot through the hillside at times also.

No i dont have a clip of the situation but i was playing co13 blackout with the ww2 mod and i was beside a wall at the south end of an installation and being tired of not having the vision the ai has so my grass was turned off. I had a sniper rifle in prone position and 2 or 3 enemy knew my position. I had my scope on the nearest guy who had an mp40 and was below my sightline down a little hill with just the top of his helmet showing. I watched as he sprayed the hillside kicking up dirt from his lower position and boom , red screen and im done. the following kill cam went straight to this fella who just hit and killed me through a foot or more of dirt! they knew i was there and if grass was turned on i would have chalked it up to cant see him but through the hillside! im not sure they actually see thru the grass but if they know your there it seems nothing prevents them from locking on you and taking you out.

lost a lot of faith in this game being so accurate if this stuff happens.

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just a little addin here, the ai can shoot through the hillside at times also.

Oh definitely. At least, they sometimes see you through entire forests and villages from a mile away. But those are anomalous detections that don't stack up with their close-range combat skills.

No i dont have a clip of the situation but i was playing co13 blackout with the ww2 mod and i was beside a wall at the south end of an installation and being tired of not having the vision the ai has so my grass was turned off. I had a sniper rifle in prone position and 2 or 3 enemy knew my position. I had my scope on the nearest guy who had an mp40 and was below my sightline down a little hill with just the top of his helmet showing. I watched as he sprayed the hillside kicking up dirt from his lower position and boom , red screen and im done. the following kill cam went straight to this fella who just hit and killed me through a foot or more of dirt! they knew i was there and if grass was turned on i would have chalked it up to cant see him but through the hillside! im not sure they actually see thru the grass but if they know your there it seems nothing prevents them from locking on you and taking you out.

lost a lot of faith in this game being so accurate if this stuff happens.

Serves you right for turning off the grass! Without grass rendered, the underlying ground is not accurately rendered and can appear different at distances.

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Max whats a marked effect? Does that mean from a certain distance?

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Max whats a marked effect? Does that mean from a certain distance?

Marked in this case means meaningful, noteworthy, or noticeable. So the darkness has a profound effect on the AI's ability to detect you with whatever approximates their visual senses (as opposed to them hearing you).

Maturin speaks the truth.

Edited by Max Power

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"Serves you right for turning off the grass! Without grass rendered, the underlying ground is not accurately rendered and can appear different at distances."

what? you telling me that the ai has a different view depending on my settings? or are you telling me the grass render is part of the ground at which point you're saying the ai sees through the grass when its rendered and shoots through the dirt when its not? or are you just making stuff up to sound knowledgeable?

the guy was approacing from down hill and shot me through the dirt. there was no " ground not rendered properly because of my settings " the guy was shooting the ground and a bullit went through it and killed my guy! oh and he was less than 50 yards away. im not buying the render idea because i sure couldnt shoot him although i tried but only kicked up dirt myself.

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"what? you telling me that the ai has a different view depending on my settings?"

I don't think we fully know. Some claims it does, others claims it doesn't, and everyone has proof :) The AI in any case doesn't "see" you, it would just be a numerical chance to trigger if they detect you on a number of factors. Hopefully grass setting would be one of those factors.

"i sure couldnt shoot him although i tried but only kicked up dirt myself."

Arma models barrel offset so that is fully possible. Note also that some "obstacles" have horrible fire geometry. What you think will be a clear shot (even after taking barrel offset into account), you will be firing into an invisible wall, ending up suppressing yourself.

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Hi all

This AI can see through grass topic has been discussed many, many, many times in ArmA; most recently here:

http://forums.bistudio.com/showthread.php?t=97157

As I keep pointing out; in actual fact the AI in every game that has ever been made does not "See" anything, period. But read what it says there and follow the link to the earlier threads on the subject and please feel free to participate in the debate and to try the test mission by NeMeSiS or create your own to put your point of view.

http://forums.bistudio.com/showthread.php?t=81935

There is a long tradition in this forum of testing scientifically. You may wish to use scientific methods to test your hypothesis and support any theory you may have on the subject.

http://forums.bistudio.com/showthread.php?t=74090&highlight=plea

As to concealment and night.

The major indicators for the AI at night are the same as for people, that is:

1) Sound: Rustling in the bushes is not a good idea. Firing a gun busts concealment.

2) Movement: When under general observation Freeze! Keep movements down to turning the head at all other times.

3) Memory: Please remember the peekaboo blanki game you played as a kiddie, running behind a bush does not make the enemy forget you ran behind it and hiding your face behind the bush does not mean you ass is not hanging out in the wind for all and sundry to see it.

4) The AI can and does use NV goggles and it affects the AI spotting algorithm

5) The the degree of Moonlight affects the AI spotting algorithm

6) The suppressor (note it is not a silencer) on a rifle reduces the enemies ability to audio locate you by your muzzle sound, flash and smoke and is config value accounted for in the ArmA spotting algorithm.

7) The silencer on a pistol reduces the chance of enemies hearing the shot but not from seeing or hearing its effects eg.

i) The ouchy! pain of being shot but not killed by the numpty who missed the Medulla Oblongata. (base of skull, top of neck area)

ii) The yelpy shout from said ouchy pain person to those AI entities in the vicinity and said yelpy calls for help to said yelpy entities team mates

iii) The person in a unit being seen as dead, or failing to report after receiving an order. "Oh no 5 is down"

iv) The thump sound of rounds missing the target but landing close (ever notice them say "... Under Fire")

Follow this link and read the section about the difference between cover and concealment and follow the links for more information and debate on the subject.

http://community.bistudio.com/wiki/ArmA_II_Hints_and_Tips

Addendum

One extra piece of advice from someone who has been playing against the AI of this game engine for a decade. Use Zeus AI it is far more realistic.

It comes as an interesting realisation that you are wishing an already two foot wide virtual tree to grow wider as large rounds from some distance are chewing it apart in front of you, while your eyes are tight closed and a long list of oaths is streaming out of your mouth, after you missed that shot with the AT.

I do enjoy ArmA.

Kind Regards walker

Edited by walker
addendum added

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I did a few tests of low terrain settings vs high, I was pleased to find out the comp can tell the difference. You can hide alot better in actual grass than just the green base left over on low settings.

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the guy was approacing from down hill and shot me through the dirt. there was no " ground not rendered properly because of my settings " the guy was shooting the ground and a bullit went through it and killed my guy! oh and he was less than 50 yards away. im not buying the render idea because i sure couldnt shoot him although i tried but only kicked up dirt myself.

Then it doesn't sound like your situation was caused by that. But the grass isn't designed to be turned off. It screws up the rendering of the ground.

But on grass in general: You have a sentient brain that can think ahead, outwit others, and eyes that can distinguish color and silhouettes, plus a wide range of spotting abilities such as the spacebar and map if you choose to use them. The grass is there to make it hard for you. Looking for a fair fight with a computer chip is ridiculous.

6) The suppressor (note it is not a silencer) on a rifle reduces the enemies ability to audio locate you by your muzzle sound, flash and smoke and is config value accounted for in the ArmA spotting algorithm.

But barely. Fire two suppressed rounds from cover at 250m and the enemy knows almost exactly where you are.

And the AI does "see" some things. Or at least there are things they don't see because bushes have that weird spiky geometry that occludes their LOS. Right?

Edited by maturin

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AI doesn't "see" graphics. Use the script command switchCamera. When a target is assigned, he will try to get into position for a shot. Every once in a while I guess AI "shoots a test ray" to test for fire geometry. If test is positive, the ray hit something and AI has no fire solution and will reposition. If test is negative, the ray hit the "assigned target box" (which is where AI assumes the target is).

One difference between us and AI is that AI tracks only a few points to trace rays against, using simplified fire geometry. Humans do this test for every pixel on the screen, using the actual graphics. Tracing a ray is a relatively costly process. Computers of today are simply not up to the task of doing this at screen resolution for each AI. Note that I have absolutely no idea how the engine "works" internally, but this is for me a reasonable assumption.

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The problem is that the AI doesn't seem to know where to move to be able to shoot at the target, it only knows that it needs to move. Also sometimes the AI will think he has line of fire but in reality there is something blocking the way so he will fire at the wall (as seen at the end of

).

Also I don't think the AI has a "knowing your general position" option, but rather he either knows exactly where you are or has a guess of where you are, but it's always an accurate position. At least that's what seems to be the case when I'm playing... Never seen AI shooting at my "general direction", always directly at a position, usually my last known position.

Also AI that have seen you before will have a very easy time spotting you when you pop up again, even if you pop back up very far away from your original position after a long enough time for it defintiely not having anything to do with him predicting your position (in fact, sometimes he will be still shooting at my last known position but as soon as I pop up turn to me and shoot me). If I would recreate the scenario with the AI looking at the same place as before ("last known position" except this time he's just casually looking at that direction) he will not spot me anywhere nearly as fast.

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Also I don't think the AI has a "knowing your general position" option, but rather he either knows exactly where you are or has a guess of where you are, but it's always an accurate position.

I just realized, pleasantly, that that is incorrect.

Look at the link Thirdup posted on the first page. I just did a lot of testing, and found that if you shoot at the AI with a sniper rifle at night, for example, they will gauge by the muzzle retort a 300m long wedge of terrain that you are inside. Then they will face that direction and watch to see if you fire again or move. If you are behind a building, sometimes they will guess that you are somewhere inside a 10m circle.

I am using Zeus AI, but I think this should all be pretty standard.

Bushes are very effective at hiding you. You can fire through one all day and the AI probably won't see you until you pop out.

Also, sometimes shooting with suppressed weapons causes the AI to become convinced that you are at some specific location in the wrong direction.

If you run behind a fence, the AI will track you accurately based on the sound of your movement, but if you stop moving and crawl away they lose you very quickly.

And lastly, I found a problem. I think we all know that the AI tracks targets based on their speed and direction once they disappear from sight. This can result in some weird Engage orders, with the little red bull's eye traveling through hills and such. This is a problem with the rather blind vehicle gunners, who often shoot at where a tank was several seconds ago, even if it has emerged from the intervening obstacle.

But to put it simply, the AI has intelligence but no common sense. If you towards a rifleman that is on a downward slope beneath you and hide behind a fence, the AI will not realize that you have stopped behind the obstacle. Rather, he will apply Newton's Laws and guess that you are flying towards him at running speed, floating several feet off the ground. He will track the spot in the air where you should be as your projected self flies over his head and into whatever building he is lying in front of. He doesn't see you where you are supposed to be, so he won't shoot. But he will then have his back turned to the real you when you pop up from cover and shoot him in the ass.

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If you play on Normal you can see how the AI tracks things when your commander assigns you a target that's out of your respective LOS's. The position is not always correct, and may actually jump around the world depending on different factors. It's a predictive algorithm that's based on your last known position, heading, and speed. If you've stayed still during that time, the AI will know exactly where you are.

Regarding the world and Terrain Detail:

Terrain detail affects the complexity of the terrain, and low settings may cause artifacts like floating trees and such. I don't know on what basis the AI keep track of terrain, though, or on what basis it is penetrable or impenetrable by firearms.

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"But to put it simply, the AI has intelligence but no common sense. If you towards a rifleman that is on a downward slope beneath you and hide behind a fence, the AI will not realize that you have stopped behind the obstacle. Rather, he will apply Newton's Laws and guess that you are flying towards him at running speed, floating several feet off the ground. He will track the spot in the air where you should be as your projected self flies over his head and into whatever building he is lying in front of. He doesn't see you where you are supposed to be, so he won't shoot. But he will then have his back turned to the real you when you pop up from cover and shoot him in the ass."

i need video proff of this! not because i dont believe you but i would love to see this purely for entertainment purposes!

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"But to put it simply, the AI has intelligence but no common sense. If you towards a rifleman that is on a downward slope beneath you and hide behind a fence, the AI will not realize that you have stopped behind the obstacle. Rather, he will apply Newton's Laws and guess that you are flying towards him at running speed, floating several feet off the ground. He will track the spot in the air where you should be as your projected self flies over his head and into whatever building he is lying in front of. He doesn't see you where you are supposed to be, so he won't shoot. But he will then have his back turned to the real you when you pop up from cover and shoot him in the ass."

i need video proff of this! not because i dont believe you but i would love to see this purely for entertainment purposes!

Download the example mission that I mentioned and you can probably reproduce it yourself.

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Download the example mission that I mentioned and you can probably reproduce it yourself.

According to

that i made years ago in ArmA1, they will stop tracking you if you dont pop up on the other side of an object when they know you should have based on your last know direction and speed, and thus 'know' you are behind it.

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According to
that i made years ago in ArmA1, they will stop tracking you if you dont pop up on the other side of an object when they know you should have based on your last know direction and speed, and thus 'know' you are behind it.

But they will begin track your progress if the object is large. For example, if you run behind a building they will track your movement as soon as you disappear. In such cases they will often fail to discern the limits of the intervening obstacle and then spin on their heels because they thing you are running through the entire village. Of course, this will often happen with hill. Sprint over a ridge and even if you hit the dirt immediately upon reaching dead ground, they will be looking for you 3km away in Chernogorsk.

Either that, or they will track your assumed movement for an excessive amount of time before concluding that you have stopped moving.

But running towards an enemy and hiding is different from running perpendicular to an enemy and hiding. In the latter case, they may not be able to gauge the thickness or density of an object, thus enabling their guess-work mode of targeting.

In short, they understand bushes very well but houses and thickets can cause confusion.

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The problem is that the AI doesn't seem to know where to move to be able to shoot at the target, it only knows that it needs to move.

Good point, and very true. Another thing is how they engage without limit instead of waiting in hide in a good defense position until the enemy is within range. That makes them get detected and dealt with far too easy. And how they don't even try to hide from overwhelming firepower. Man vs big ass vehicle, and he figures the middle of the street is a nice place to lay down :D

For scripters, we tend to go with fairly easy to calculate flanking manouvers. Sometimes the terrain work good for this, sometimes not. Terrain analysis is way beyond scripting possibilities (maybe somewhat possible, but not in a timely fashion needed in missions).

I think a good approach would be "nodepoints" automatically created by the terrain editor. Consider them "invisible roads" in which AI can be instructed to follow them loosely or strictly. Always on either side of a ridge and AI would tend to choose the far one during a maneuver to stay hidden. Where is the threat, and where is it heading? Then find a suitable hidden route to a node where expected position will be observable. Such precalculated routes would ease the pathfinding process as well, which takes considerable time for long relocations.

Each "nodepoint" would have a number of attributes, such as defensive and offensive value, is it reversed slope, can it support indirect weapons, accessibility, terrain type (woorland?), visibility factor, resupply route easiness, whatever. All these factors in respect to to all near neighboring "node points". We could input a lot of factors to a function who would then lookup this data, and get a predetermined route depending on the attack force, orders, and all those other tactical factors. Think of it as "locations", but where values will change with respect to "another location". "Node A" may not be a good place to defend from if enemy is closing in on "Node B", but "Node C" might have much higher values.

Feasible? I have no idea, would require handling of huge arrays or some new database handling system. And for an entire island, data storage would be massive. Just airing the thought :)

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Probably not feasible, as the more you want it to look natural the more data you'd need to even save the points, not to mention manpower (or worse, computation power and algorithm) to figure out which point should have what values.

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Something that is left out in this whole discussion is how the ai works as a group.

I've seen interesting stuff happen like

-open fire on a squad that's just behind a ridge.

-retreat behind the ridge.

-Sometimes you get half the team doing a frontal suicidal attempt, half flanking left side, half flanking right side.

-Sometimes there is only a left flanking side, sometimes only a right flanking side

-Sometimes the whole squad does suicidal frontal attempt.

What i'm not too sure of is intersquad communication (i don't really know what is scripted anymore and what isn't) but combine them all and they form a great enemy.

I don't think it's very easy to make ai that's good enough to stand its ground against 30 human players and still run on a moderate cpu.

Also the newer covering formations they use in CQB tend to cause a lot of human casualties and it's really fun to see how they sometimes outwit human players using algorithms.

The grass however is a still a big problem (i don't like playing with it on at all). It tends to cause human players to stack up on non grassy areas. The best and simple solution i saw for this problem was the shortened GDT grass addon. I personally don't understand why BIS doesn't shorten the grass or make the grass length optional.

The way the bushes work is great i think. Completely beats the original OFP approach where a bush could be a magical "now you see me, now you don't" shield for ai's.

Same goes for the approximate leading you last know position, now you can really get pinned down in a building which was near impossible in the original OFP.

Of course this can have funny effects like a t90 using mg's on a building's window instead of simple shooting down the entire building with main gun. But something tells me if ai would actually do that, a lot of people would start hating the game.

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