So I’ve been playing around in the editor and ran a bunch of tests with different units, terrain types like forests and buildings, and various distances. I don’t know the exact formula the game uses behind the scenes, but based on what I’ve seen so far, this is how things seem to work.
I’ll update this guide if I find out anything new or if any of my assumptions turn out to be wrong. And hey, if you spot a mistake, feel free to correct me — I'm just trying to keep my guys hidden and the enemy in full view, just like you probably are too!

Spotting Distance = Spotting Value / Stealth Value
So the higher your spotting value is, or the lower the enemy’s stealth, the farther away you can see them.. as you may already know.

Infantry in Buildings or every Unit in a Forests: Their spotting distance gets cut in half.
Advanced Spotting Distance = Spotting Distance / 2

• Once a unit is spotted, it stays spotted until it’s completely out of your normal spotting range (not the reduced one for forest/buildings).
  
• If a unit fires its weapon, it temporarily loses its stealth bonus and becomes easier to spot. After a short delay, it goes back to normal.
  
• Doesn’t matter if the unit is hiding — if something is inside your spotting range *See basic Rule* and just shot, it stays revealed.

I put some American Scout Snipers in the enemy team. They have a stealth value of 3.
Then I used one of my own units, also Scout Snipers, with a spotting value of 2000.

Here's the math:
2000 / 3 = ~666m
So I was able to spot them at about 666 meters in open terrain.
When I put them in a forest or building, that range got halved to ~333 meters.




Next test, I used American Airborne Snipers with a spotting value of 2000 (same as before).
Then I placed these enemy units at different distances:

Enemies & Their Stealth:

• Motopekhota (infantry) – Stealth: 1.75 - [Spotted at: ~1140m; Forest/Buldings ~571m ]
  
• Diversanty (recon) – Stealth: 3 - [Spotted at: ~666m; Forest/Buldings ~~333m]
  
• T-14 Armata (tank) – Stealth: 1 - [Spotted at: ~2000m; Forest ~1000m]

Helicopters are a bit tricky when it comes to spotting. The number shown in the optics value (binocular icon) can be misleading — because they don’t actually use that general value.

If you hover over the icon, you’ll see more detailed optics values depending on altitude — that’s what really matters.

Here’s how it breaks down (using the American AH-1Z Viper as an example):

Optics (Ground): 2000m
→ Spots ground units like tanks and infantry.

Optics (Low Altitude): 2500m
→ Spots low-flying air units like other helicopters.

Optics (High Altitude): 2000m
→ Spots high-flying air units like jets or bombers.

Once a helicopter spots something — like a tank — it won’t just stick to the value it used to spot it. Instead, it uses the highest relevant optics value it has to keep that unit visible.

So for example, if my AH-1Z Viper spots a T-14 Armata (Stealth 1), it will continue tracking it using its Low Altitude Optics value of 2500m — even though it originally spotted the tank using its Ground Optics (2000m).





That means the tank will only disappear if it moves beyond 2500m, not 2000m.
I don’t know if this is a bug — but that’s how it behaves in my tests.

TL:DR Low-flying drones do the spotting. High-flying drones keep the vision alive.

There are various drones in the game, and I've roughly categorized them by altitude:

• Low Flyers: e.g. RQ-7 Shadow
  
• High Flyers: e.g. MQ-1 Predator, MQ-9 Reaper, RQ-4 Global Hawk

The key difference is how well they can spot infantry, especially stealth units like Ranger Snipers and Scouts.

High Flyers (MQ / RQ Variants)

• Fly at altitudes around 800 meters, and circle about their target destination with a distance of 1050-1150 meters.
  
• Cannot spot stealth 3 infantry in buildings or forest, but there is a trick.

Low Flyers (RQ-7 Shadow)

• Flies lower and is slightly more vulnerable.
  
• Able to detect stealth infantry reliably in buildings or forest.
  
• Alone weak and cannon foder but in tandem with the High Flyers, great!

Combined Drone spotting
Friendship is… intelligence sharing? Well, using the RQ-7 Shadow to initially spot hidden enemy infantry allows a high-altitude drone like the MQ-1 Predator to continue tracking the unit after the RQ-7 leaves the area.

• MQ-1 Predator (orbiting at 800m+) cannot spot the snipers on its own.
  
  
• RQ-7 flies low and spots Ranger Snipers.
  
  
• But after the RQ-7 tags the target, the MQ-1 maintains vision, even after the RQ-7 is gone.
  

But how about the "RADAR"?
The enemy’s active radar doesn’t improve your drone’s spotting ability — instead, it increases the distance at which your drone loses contact with the radar vehicle, allowing it to stay spotted at an enormous range! In this example, the Patriot PAC-2 radar vehicle remained spotted by MQ-1 Predator up to 6000 meters away before losing contact!


Some tables with data:

TL:DR:
Planes and jets can't spot ground targets.
Their spotting value for ground units is zero—literally 0 across the board.

One Exception
There is one exception: the AC-130J.
It’s the only plane that can spot ground targets. Think of it as your airborne scout gunship.

So… Why Use Jets Then for spotting?
Ever heard of the AGM-88 HARM missile?
These missiles lock onto active enemy radar.
Even if your plane can’t see the radar station directly, the HARM doesn’t care—it homes in on the radar emissions and smashes the target.

Now let’s say you fire a HARM at an enemy radar site.
What happens next? The enemy AA systems (like Patriots) wake up and start firing back.

But here's the catch:
Even now, your plane still won’t see those AA units. It literally can't—it’s blind to ground targets.
If you want to reveal and target them afterward, you’ll need something else.
Use a recon drone, ground scout, or another spotting unit to light them up.


Plane-to-Plane Spotting and Why Altitude Matters
What I found out during testing:

• If a spotting plane is flying at high altitude, it uses its high-altitude spotting value to detect both high and low-altitude targets.
  
  
• If it's flying low, it uses:
  • Low-altitude spotting for low-altitude targets
    
  • High-altitude spotting for high-altitude targets

Plane-to-Helicopter Spotting
Jets handle spotting helicopters differently than spotting other planes. The key rule:
Jets always use their low-altitude spotting value when detecting helicopters, regardless of whether the jet itself is flying high or low.

Consider a Longbow AH-64D helicopter and an F-15C Eagle jet:

• Longbow AH-64D: low-altitude spotting 3200m, high-altitude spotting 2000m, stealth 1.25
  
• F-15C Eagle: low-altitude spotting 4000m, high-altitude spotting 12000m, stealth 1.0

At low altitude, both spot each other at about 3200m (Longbow: 3200/1, F-15C: 4000/1.25).
At high altitude, the jet’s spotting against the helicopter is still based on its low-altitude spotting (4000/1.25 = 3200m), but the helicopter spots the jet later due to its lower high-altitude spotting value (2000/1 = 2000m).


Good-to-Know: Stealth Planes
Planes like the B-2 Spirit or F-117 Nighthawk have a stealth value of 1.75.
Doesn’t sound like much? Well, for aircrafts, that’s pretty good.

Most jets have a spotting value of 6000
→ They won’t see the B-2 until 3400 meters

High-end jets with 12000 spotting
→ Still won’t see the B-2 until 6800 meters

That’s a lot of sneaky space to operate in before being detected.

Short answere, yes they work.. kinda
I used the LVSR truck with a spotting value of 1000 as the spotter, and tested against Ranger Snipers (Stealth 3) in different situations — like with and without suppressors, inside buildings, and while shooting or staying quiet.

Suppression delays being spotted, but doesn’t make you invisible.

• When Ranger Snipers used suppressed weapons (range 900m), they were only spotted at 600m, and lost at 900m, without the advantage of buildings or forest.
  
  
• With unsuppressed, long-range weapons (range 1200m), they were spotted much earlier — at 1200m, and stayed visible. Interesting to notice is that the spotting range of the LVSR is only 1000.
  
  
• A sniper firing from a building with a suppressor stayed hidden longer.
  
  
• In one case, they were spotted at 700m, but lost again at 560m — because the building stealth bonus came back before they could shoot again (their weapon had a long fire delay).

My thoughts
In my opinion, using stealth units like snipers to set up ambushes can give you the first shot — which is nice — but they’re super fragile and usually don’t survive a full fight. They're much better for sneaky harassment in the enemy's backline: picking off AA units, artillery, or logistics trucks trying to bring supplies to the front or just being good spotter.

Let’s talk ambushes - because someone brought it up in the comments…

In this setup, I parked a Stryker ATGM with Stealth 1 inside a forest, lying in wait to blast an approaching LVSR truck.

To help the Stryker out — since its own spotting value is only 1200m — I used Scout Snipers as dedicated spotters. That way, the Stryker can stay hidden in the woods while already having a visible target to shoot at.

I did this because the TOW-2 missile has a longer range than the Stryker's spotting distance — so I wanted it to fire before it would normally even see the enemy, in this case, the LVSR truck.

Well... it works, as you can see here: you can already see the explosion decals under the truck.


But how about without the forest?
It works too! Just... worse.
Without the forest’s stealth bonus, the Stryker ATGM is way easier to spot once it starts firing. You'll still get that first surprise shot if someone else is doing the spotting, but staying hidden gets a lot harder. So yeah, ambushing from the open? Risky but doable.



Quick note: The reload time of the TOW-2 is around 8–12 seconds — just enough for the forest stealth buff to reset. So if the enemy doesn’t have eyes on you during that downtime, you can stay hidden and fire again. Just like the snipers in the earlier section.

Keep in mind that spotting distance is always “up to” a certain range — not a guaranteed detection the moment something enters that distance.

So if the math says you should see a unit at 1000m, it might actually get spotted a bit closer, like 950–990m. Why?
Because the whole unit (or at least enough of it) needs to be fully inside your spotting range. If just one guy from an infantry squad steps into your spotting bubble, that might not be enough to trigger detection right away.