Troubleshooting#

Symptoms first, causes second. For almost everything, the fastest tool is the Visualizer: tick Show Visualizer on the APS Core and read its Senses page (Visualizer & debugging).

Nothing works at all#

Check these first; one of them is almost always it.

1. The APS Core is on the Pawn. On an AI Controller it logs APS Core is on the controller... and stays off. Move it to the Pawn or Character Blueprint.
2. A profile is assigned to the APS Core's Profile. Without one, a moment into play APS logs APS Core on '...' has no Perception Profile.
3. The profile has senses. An empty Sense Classes logs Profile '...' runs no senses. A new profile starts with Vision Sense and Hearing Sense.
4. You're playing. Perception doesn't run in the editor viewport.
5. You're on the server. Perception runs on the server only: in Play with several clients, test in the server window.
6. Print Explain Perception (Get Player Character) on the AI: it says, per sense, what it reads or why not.

It never detects me#

It detects me instantly, from anywhere#

The Visualizer's Senses page shows which sense is high. It is usually Hearing or Vibration.

It sees through walls#

1. Add the wall's collision channel to Vision Occlusion Channels. Empty means Visibility only; a list replaces Visibility, so list it too if your walls block it.
2. Check the wall really blocks that channel.
3. Check Surface Vision Transmission: a surface at 1 is fully see-through.
4. Check which sense it is: Vibration and Echolocation are meant to pass through walls, and so is the crowd tier.

It sees me the moment I step into its cone#

That is Unreal's perception's behaviour; APS softens it three ways: First Spot Reaction Time 0.3 to 0.5, a lower Confidence Rise Rate, and Keyhole Vision so distance protects you. If it sees you before it has turned, set Eye Turn Rate Deg Per Sec (0 is instant) to about 180 to 300 for a person.

My light gem is ignored#

Light Level Override on the APS Target Component wins whenever it is 0 or more, whatever the profile says; -1 lets APS work light out. If it still seems ignored, check Darkness Min Detection: at light 0 the AI still sees at that strength (0.1).

It perceives much worse when hurt#

Pain Sense reads the AI's health by itself (the APSHealth Provider interface, or a GetHealthPercent, GetHealth or GetCurrentHealth function with GetMaxHealth) and dulls every sense with it: at half health, half strength. Implement APSHealth Provider and return 1, or take Pain Sense out of the profile. Emotions & pain

Hearing#

It hears nothing. Hearing hears only what you emit: something must call Emit Sound (or Emit Sound at Location). Then check:

• Hearing Sense is in Sense Classes;
• the sound type's Max Range covers the distance;
• a Sound Filter isn't rejecting it: an **empty Accepted Categories makes the AI deaf**, and Min Alert Level may be above the sound's Alert Level;
• the AI's tier isn't above the sound's Max LODTier (raise it to 4 for explosions everyone should hear);
• Emit Sound ran on the server.

A thrown can never fires On AI Hear. Correct: a noise nobody made is a belief about the place. Bind On Location Belief Changed or read Get Strongest Location Belief. Hearing

After a noise it follows me through walls. While the noise build-up lasts (Sound Accumulation Hold Time, 1 s, then it fades at Sound Accumulation Decay Rate, 0.2 a second), hearing places you where you really are, and On AI Hear keeps firing with Sound Type Name None. Shorten the hold, raise the decay, and in your Blueprint ignore On AI Hear when the name is None. Hearing

Explosions don't shake my vibration AI. The sound type's Sound Name must be exactly Explosion, and the AI within its Max Range. Emit Sound and Emit Sound at Location both shake the ground.

It reacts to every footstep at once. Lower Sound Accumulation Rate, raise Suspect Threshold, give it a Sound Filter with a higher Min Alert Level, or lower the sound's Base Loudness or Max Range. (Hearing Base Threshold looks like the setting for this and does nothing: see below.)

Smell ignores my wind. Set Wind State's Direction is where the air goes; Speed must be above 0; indoors there's no wind; and a Smell Sense child with its own Wind Direction uses that instead. Smell

Memory and search#

Events#

My event never fires.

1. Visualizer, Events page: did it fire?
2. It fired: your binding is wrong, or on another component. A Listener must be on the same actor as the APS Core.
3. It didn't fire: the change never happened. Back to the Senses page.
4. The target is a body or a forced lock: a thing, not someone; no event names it (Search & evidence).
5. On Replicated State Changed fires on clients only: never on a listen-server host or in single player (Multiplayer).
6. On Emotional State Changed is on the APS Core only, not on the Listener.

I can't add the Listener's events to my AI's graph. A component's events are overridden in a Blueprint of that component: make a Blueprint from APS Perception Listener, override them there, and add it to the AI. Or use the events on the APS Core (Details › Events, +). Getting started

I can't find On AI Lost. It's On AI Lost on the APS Core and on the Listener. Before 3.0 the core's was called On AILost Event; Blueprints saved with the old name load with the new one.

Squads#

Multiplayer#

Performance#

The frame rate drops with many AI. In order: raise Base Update Interval; trim the Target Component's Visibility Samples (or cap them with a Quality Profile); lower Max Tracked Targets; one occlusion channel; Use Per Target Light off on background AI; a far Quality Profile. Performance & crowds

Is it APS? Tick Pause Perception on every AI. If the frame rate doesn't improve, the cost is elsewhere.

My idle AI never run at full rate. By design: an AI reaches tier 0 only once it is Suspicious or more alert.

Install and packaging#

Settings that do nothing#

These are visible in APS 3.0 but change nothing; the reference marks each one.

Two more behave differently from their names:

• Vision Sample Count only limits the built-in point set: a target with an APS Target Component uses its own Visibility Samples.
• Respect Never Search Zones only changes what Is Location in Never Search Zone answers: nothing is enforced.