Spotting

In Broken Arrow, a unit spots an enemy within its optics range multiplied by the enemy's stealth, as long as terrain does not block the line between them. From the game's data Cover, firing and radar change that distance, and a few of the details are still unknown. From the game's data

Optics: three bands

Each unit's sensor gives three optics ranges. Ground optics is for ground units, Low-altitude optics for helicopters and low-flying planes, and High-altitude optics for high-flying planes. From the game's data They are the spotter's reach in the open, before the target's stealth and cover count. Worked out by this site A loadout option can swap the sensor, and so the optics; see loadouts. From the game's data

The game shows every distance doubled relative to its data. From the game's code This site shows optics the same way, as the game shows them. Worked out by this site Two of the game's sensors, as the game shows them: From the game's data

The data holds half of each figure: Good Optics is 875 data metres on the ground. From the game's data The game's patch 1.2.1 notes agree: they set the Spetsnaz Vympel's optics to 1.75 km, which is that same 875 doubled. From the game's own text

Stealth is a multiplier

The game stores a unit's stealth as a multiplier on the spotter's range, and shows it as 1 divided by that multiplier. From the game's data So a sniper stored at 0.333 is shown as stealth 3, and enemies spot it at a third of their optics range; players' guides put the same rule as optics divided by stealth. From the game's data

Stealth values of the units in the current armoury: From the game's data

No unit in the current armoury has a multiplier above 1, so none is spotted from farther than the spotter's optics. From the game's data

A worked example: a spotter with Good Optics sees a stealth 3 sniper in the open at about 580 m, as the game shows it (1,750 m × 0.333). Worked out by this site

Cover: forest and buildings

Forest and buildings double a unit's stealth, which halves the distance it can be spotted from. From the game's data In the game's fog of war settings both have a cover value of 2, and every other terrain type has 1; players' tests find the same halving. From the game's data

In forest, the sniper above is spotted at about 290 m, as the game shows it. Worked out by this site

Always seen within 45 m

A unit within 45 data metres of an enemy, 90 m as the game shows it, is always detected. From the game's data The game's settings call this the minimum detection distance, and it is a distance on the map, not a shown one. From the game's data

Sight lines and terrain

Terrain blocks a sight line where it rises more than 1 m above the line. That figure is a setting of the game's line of sight tool (hold Alt), and players' tests agree that hills block sight. From the game's data

Forest and smoke limit sight too. Players report that smoke blocks it, and that a unit inside a forest sees only a short way. Not known: our best reading The game's settings give forest and smoke each an opacity, a height and a multiplier, but how those combine is unknown. Not known: our best reading

The map planner draws vision with these rules. Worked out by this site

• Range is optics × stealth ÷ cover, and never less than 45 data metres.
• Terrain blocks a line it rises more than 1 m above.
• Forest stands as a canopy of its own height above the ground.
• Forest and buildings within 45 data metres of either end of the line are ignored.

The 2 m eye height and that 45 data metre allowance are this site's own choices, so the planner labels its results as estimates. Worked out by this site

Losing cover once spotted

A spotted unit loses its cover bonus, so forest or buildings stop doubling its stealth. From the game's data The game's settings carry a "spotted penalty" of 2, and a second one of 2 for buildings; players' tests describe the same effect. From the game's data Players' guides add that the bonus stays lost while the enemy keeps line of sight. Not known: our best reading

One player reports that a spotted unit stays visible until the spotter is twice the detection range away, or sight is blocked. That is a single report, and we have not confirmed it. Not known: our best reading

Firing gives you away

Firing lowers a unit's stealth for a while. From the game's data The game's settings hold a maximum "flash" of 4.5 and a flash reduction of 0.15. From the game's data Players report that rapid fire can push stealth below 1, and that suppressors and forest slow the loss. We have not confirmed this. Not known: our best reading The rate and shape of the loss are unknown. Not known: our best reading

Radar

A radar raises a unit's reach against aircraft: both its optics and its weapons' range. From the game's own text While it is on, it multiplies the low and high altitude optics by ×1, ×1.25 or ×2, and the weapons' low and high air ranges by ×1, ×1.25, ×2 or ×3. From the game's data A loadout fields at most one radar. From the game's data

The 2K22M Tunguska-M is an example. Its optics are 1,000 m ground, 3,200 m low and 2,000 m high, as the game shows them. From the game's data Its radar multiplies low altitude by 1.25 and high by 2, so both air bands reach 4,000 m, as the game shows them. From the game's data On a unit page, the low and high optics rows show the radar-on reach as a second column. Worked out by this site

Whether a radar also moves a weapon's minimum range is unknown. Not known: our best reading

What is not known

Not known: our best reading

• How the opacity, height and multiplier of forest and smoke combine.
• How fast stealth falls after firing, and in what shape.
• What a setting named "MaxAntiVisible" (1.5) caps.
• The eye height of a ground unit.
• Whether a radar moves a weapon's minimum range as well as its maximum.