Feature #18956

Improve perceived position design for AI infantry

Added by kju almost 4 years ago. Updated over 2 years ago.

Status:Assigned Start date:04/16/2011
Priority:Normal Due date:
Assignee:Dwarden % Done:


Category:AI Issues
Target version:-
Affected ArmA II version:1.60 BETA First affected ArmA II version:
Reproduced by another DH user:No Single / Multi Player?:
I am using some Mods:No BIForumURL:
I am using: NGUrl:
Reproducible for you:Yes WIKIurl:
Related to content of DLC:


AI infantry tries to guess the possible position of a target,
when it looses direct visual contact.

However the design seems very simplistic and does not include
some corrections, like

  1. The target moves behind an small object like a stone or short wall
  2. The AI assumes the possible position based on the last visible motion
  3. This means it think the target moved behind the object and continues to move the same path
  4. While the target stops behind the target rather to move again into the open
  5. The AI sees that the unit does not move into the open again
  6. Yet it still follows the potential position moving into the open

The perceived position updating should be stopped once the AI would
had to see the target again.
So right after the object in the open.

This is mainly a problem as in some modes and waypoint combinations
the AI follows the perceived position with its view and weapon aim.

Note 2
Even better would be, if the AI could understand that the target is
hiding behind the object.

PerceivedPosition.Desert_E.7z (1.6 kB) kju, 04/16/2011 08:15

PerceivedPosition1.jpg (441.8 kB) kju, 04/16/2011 08:15

PerceivedPosition2.jpg (411.3 kB) kju, 04/16/2011 08:15

PerceivedPosition3.jpg (412.9 kB) kju, 04/16/2011 08:15

PerceivedPosition.avi (7.2 MB) kju, 04/16/2011 08:16

PerceivedPosition2.avi (10.6 MB) kju, 04/16/2011 09:19

18956.chernarus.7z (1.7 kB) kju, 08/08/2011 14:21

PercievedPositionFromHearingMovementByAI_.avi (2.4 MB) kju, 08/10/2011 10:52

Related issues

related to ARMA2 Community Issue Tracker - Feature #17643: Make AI able to recognize a target better when looking at... Assigned 02/14/2011
related to ARMA2 Community Issue Tracker - Bug #23150: DCEnemyDetected is triggered multiple times per threat de... Expired 08/05/2011
related to ARMA2 Community Issue Tracker - Bug #23300: AI can even hear slow movement Assigned 08/10/2011 11/01/2011
related to ARMA2 Community Issue Tracker - Feature #42413: Improve AI info share system and AI weapon use on non vis... Assigned 08/19/2012
related to ARMA2 Community Issue Tracker - Bug #28022: AI fixates on perceived source of gunshot, does not adjus... Assigned 01/20/2012
related to ARMA2 Community Issue Tracker - Bug #23301: AI is unable to pointpoint sound source (well) Duplicate 08/10/2011 11/01/2011
duplicated by ARMA2 Community Issue Tracker - Bug #18830: Adjust 'perceived position estimation' system Duplicate 04/11/2011


Updated by kju almost 4 years ago

Updated by kju almost 4 years ago

Another video showing AI blindly watching at the perceived position - this time perceived position by hearing.

PS: Something seems wrong with the hearing to perceived position system in addition.

Updated by maturin almost 4 years ago

  • File mission.sqm added
  • File knowsabout.sqs added
  • File Ascriptididntmake.sqf added

Attached are files for an editor-ready mission.

It's designed as a bush viewblock test but includes a knowsabout perceived position script.

Procedure: Display yourself to the AI by strafing right, then quickly run back behind the bush.
Expected Result: Perceived position arrow will move fifty meters past the bush at the speed of a running man. It will then stay in place and the AI will aim at it until you show yourself again.

Also note that, like kju says, sound is messed up. No matter how many times you fire your weapon, the AI will not perceive that you are behind the bush, but will look in completely wrong directions and distances.

Updated by kju almost 4 years ago

Always attach a mission pbo or zipped up mission folder. Thanks.
Will delete the single files in some days.

Updated by Suma over 3 years ago

Just to explain what you see:

5. The AI sees that the unit does not move into the open again

Here is where the trouble is. The AI does not see it. If the AI should see it, it would be necessary to check the line of sight between AI and the predicted target position, which is something not done (and not needed) now. With such information it would be possible to assume AI position may be somewhere when the line of sight was not clear. As line of sight tests are quite expensive, I am a bit afraid to implement such test, but I agree the added value for AI would be significant in many situations.

Updated by zGuba over 3 years ago

Maybe performing such checks only when AI is targeting player controlled/commanded vehicles would be sufficient in most situations? AI vs AI is a roulette anyway.

Updated by kju over 3 years ago

  • File deleted (mission.sqm)

Updated by kju over 3 years ago

  • File deleted (Ascriptididntmake.sqf)

Updated by kju over 3 years ago

  • File deleted (knowsabout.sqs)

Updated by kju over 3 years ago

Demo mission from maturin

Updated by kju over 3 years ago

I understand the problem. Here are a few ideas:
  • The LOS sight could be done only every 1/10s, 1/2s or even only every second (for this situation).
  • It could be two layered. Simple check very frequent, complex check (LOS) only at low cycle time.
  • Maybe one could think of additional conditions when the AI had to do such LOS check (not aware of the threat's position basically - maybe more to reduce the probability)
  • Shorter timeout - it seems that after some seconds the AI falls back to the last known position. If this would be reduced, the problem would be lessened.

Updated by kju over 3 years ago

Here is a related video: Perceived position from hearing movement by AI

It shows:
  1. AI judgement from only hearing movement seems off (at times more, at times less)
  2. The long timeout makes the AI look at not sensible areas for too long (in this situation at least)

The player waypoint and the red sphere show the estimated position.

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