Spotting is the process of having a unit or upgrade reveal other Regions units. It repels the "fog of war" that ordinarily hides units outside player units's field of view. Some units may not be visible under certain conditions. What is actually spotted is affected by a number of factors that are listed below.
Lack of spotting ability in a hex (fog of war) does not prevent the player from seeing upgrades that exist or are being built there. It applies only to units. Additionally, spotting and fog of war may be turned off completely in advanced settings.
Spotting strength of an observer varies according to its Spotting Type. Spotting strength is how well a unit can detect other units without any other modifiers. It may be low, medium, or high. Higher is better. Low spotting strength is generally found on ground units, medium spotting strength on fighter/bomber and interceptor aircraft, and high spotting strength on AWACS aircraft and naval ships.
Stealth strength of target or Stealth strength is how well a unit can hide itself from spotting units.
Distance from observer to target effects apotting. In Advanced LOS mode, the distance from the observing unit to the unit being spotted will decrease spotting ability.
Many units may be hidden so long as they are stationary, and visible only when they move. A unit's full stealth strength is used only when it is stationary; when it starts moving, it loses about half its stealth strength. And if it starts firing, it loses half again (75%) when it begins firing.
An extreme level of stealth is found in stationary special forces infantry, which may not be visible until an opposing unit enters the special forces unit's hex. Anti-aircraft units are also often only briefly visible when they fire.
Target in an emplacement, city, or broken terrain Units will be more difficult to spot in certain terrain. For instance, a unit in an emplacement is more difficult to spot. So too are units in heavy forests, mountains, or metropolitan areas.