Active camouflage

''This article describes the Covenant cloaking technology. For other uses, see Camouflage (Disambiguation).''

The term Active Camouflage (often shortened to Active Camo) refers to the Covenant-developed light-bending energy that is generally stored in small, deliberately fragile containers.

Description
In Halo: Combat Evolved and Halo 2, it is stored in a small, glass-like pyramid; in Halo 3 it is suspended in a spherical force-field. A person can use the light-bending energy by merely coming into physical contact with the container, which will cause it to break and release its contents. Upon release, the energy envelops the wearer and bends light around their skin, armor, or shielding, conforming to their form and rendering them almost invisible. At that point, the energy will gradually dissipate and wear off, slowly revealing its user.

The effect lasts only for ten seconds, and only prevents visual detection; those using Active Camo can be detected through other means, including motion trackers, any noises they make, and any changes to the environment that result from their movement (things like footprints on soft terrain).

Being a Covenant device, Active Camo is most commonly used by Special Operations Elites, Stealth Elites, and Brute Stalkers. However, all varieties of MJOLNIR armor after and including the Mark V can also use the technology.

Function
Active Camo will easily cloak its user, but its effect does not completely extend to items in the user's possession; Human weapons are easily cloaked, but Covenant weapons are visible even with Active Camo, as the light-bending energy cannot mask the glow of the weapons' plasma. In Halo, however, plasma glow is hidden quite well by the powerup.

Though Active Camouflage is quite effective from a distance, it can faintly be seen if an observer is close enough to the wearer. However, it is difficult to spot a camouflaged opponent from a distance using a scoped weapon -- actual physical proximity is required to reliably spot a person using Active Camo. It should be noted, though, that Active Camouflage does not mask environmental effects such as footprints, meaning that it is not as effective on soft terrain (such as the snow found in Halo 3 ' s and  Multiplayer maps).

The shielding provided by Active Camo can be disrupted if projectiles pass through it; such a disruption weakens the invisibility effect and temporarily reveals the wearer. The powerup can be disrupted if the wearer fires shots or if the wearer is hit. It also progressively worsens: the longer the wearer fires (or is hit), the more visible they become. Once the disruptions end, however, the wearer quickly regains their invisibility.

Science
Technically, Active Camouflage is not quite invisibility, though it is very similar. Rather, it is the term that is used to describe a broad range of technologies that allows a wearer or object to blend in with its terrain, mimicking the environment around it perfectly, though in two dimensions. There are a variety of ways to do this, though the UNSC uses photo-reactive panels on its Semi-Powered Armor and Prowler warships for optical camouflage, adapting to account for movement.

Though it has never been elaborated on in detail, it is suspected that Covenant versions of the concept use phased array optics to project a three-dimensional hologram of background scenery around the wearer of the system, effectively bending light, a task well within the Covenant's tier two technology level. The technology can be utilized on Human armor systems, such as the MJOLNIR armor, but the UNSC has only developed a rough equivalent, the Camouflage Cloak.

Talc powder and other atmospheric particles can disrupt the systems, causing the technology to overload and fail. The device also generates a considerable amount of heat, causing its user to be clearly visible on Human thermal goggles and some variations of the Sniper Rifle. The humans of Alpha Base on Installation 04 used this advantage when their base was infiltrated by stealth Elites, equipping their Fire Teams with infrared goggles allowing them to easily see the attackers. In addition, William and Kelly employed talc powder in order to overload the camouflage on Reach in order to find them, though this appears to have been altered in the games.

UNSC
The UNSC has developed various technologies for the same purpose as the active camouflage; to conceal a soldier or any object from view. The most common form of this technology operates on a different principle than the active camo, using photo-reactive panels to impersonate the surrounding environment like a chameleon. A device known as the Camouflage Cloak can hide the wearer's infrared signature, beside serving as a form of camouflage. However, UNSC camouflage technology is inferior to Covenant active camouflage in many respects.

The Semi-Powered Infiltration Armor used by the Spartan-IIIs utilizes photo-reactive panels to conceal the wearer's infrared signature and to blend in with the surrounding environment. When combined with their natural talent and training for stealth, it can be a very effective tool. Some Headhunters use a prototype camouflage almost identical to the Covenant version, rendering them almost invisible, except that it only lasts 3-5 minutes and other systems have their power drained while it recharged. This feature was tested by ODSTs and saw very limited use in 2552.

Much like the SPI armor, UNSC Prowlers use ablative panels to conceal themselves from view in addition to masking their heat signatures. However, more advanced stealth ships were developed, an Unnamed Stealth Spacecraft using a form of cloak "bubble", and the Prowler which allegedly used a form of active camouflage "skin".

Changes in Halo
If the Active Camo is active during Campaign, you are completely invisible to the AI enemies unless you fire your weapon. Active camouflage is only usable in Campaign when you are playing as the Arbiter in Halo 2, obtain the Envy Skull and restart Campaign in Halo 2 (replacing Master Chief's flashlight), or if you pick up Cloaking in Halo 3. It is also available as a powerup in five levels during Halo: Combat Evolved:, , , , and.

An interesting fact about Active Camouflage is that although you can see the Sword-wielding Active Camo Elites in Halo: Combat Evolved (due to the sword), the Marines cannot see them; this is likely because the developers didn't realize that the Energy Sword showed through the Active Camo, leading them to code the Marines' AI to be oblivious to it. This advantage is removed in Halo 2 -- the Elites now wait, only activating their swords when they're about to kill you.

Halo 2
In Halo 2, it is noted that the Arbiter's armor, while possessing a built-in active camouflage generator, is not permanent, unlike the more modern generators used by Special Operations Elites. There is a circle on the player's HUD that shows the amount of time left for both the usage of the active camouflage and the recharging sequence. The Master Chief can gain this ability with the Envy Skull on Legendary only; however, his screen will lack the meter, forcing you to remember the time allowed for use.

When playing as the Arbiter, using any attack will cause the active camouflage to deactivate, and the player must wait for it to recharge before using it again.

Halo 3
In Halo 3, the Active Camo is no longer contained inside a pyramid construct. Instead it appears as a large, glowing sphere with what appears to be containment devices around it, enclosing the powerup in Halo 3 multiplayer; but unlike past Halo games, active camo is not found in campaign. In campaign, Active Camouflage is replaced by the Cloaking equipment, which functions in the same way as active camouflage once did. Melee attacks, shooting, throwing grenades and using equipment will negate the effect of the power-up. Also, wearing the Flaming Helmet is an obvious give-away to the opponent because the fire is still visible.

The quality of camouflage in custom games may be set to two different settings :
 * Poor Camo: The player has camouflage that might fool a Grunt.
 * The player is still somewhat visible.
 * Good Camo: The player has camouflage that will fool an attentive Elite.
 * This makes the player almost invisible, but the light is distorted within the player's shape.

Halo: Reach
The Active Camo in Halo: Reach has undergone many major changes. It is now available as an Armor Ability. When used, it jams the player's radar. Crouch walking increases the effectiveness and duration of Active Camo's cloak.

Trivia

 * Changing the graphics card settings on Halo PC (lowering the quality and effects) makes active camouflage users appear as an easily-seen gray, opaque silhouette.
 * On, if you go right off of the fallen tree towards a small indention in the hill, you will find an Active Camouflage next to the pipeline.
 * The Separatist Phantom in Halo 3 has its own Active Camouflage generators on board for various stealth missions.
 * Oddly enough, a group of Major and Minor Grunts in the Halo 2 level used Active Camouflage as they fought alongside a group of Stealth Elites. This suggests that at least some lower ranked Grunts have this equipment.
 * As stated in the Halo 2 Piggyback Official Guide, when used in association with an Overshield, the Active Camo becomes completely useless due to the charges of the overshield washing over the player's body (except in Halo: Combat Evolved). In Halo 3, the same effect occurs when Active Camouflage and Overshields are both working.
 * The Active Camouflage has no effect on the flames on the Bungie Employee flaming helmet, allowing enemies to more easily locate the user of the helmet.
 * With the Envy skull on in Halo 2, the Master Chief's flashlight will be replaced with active camouflage. This can also be combined with a glitch which allows you to reload from a checkpoint, after saving and quitting, and turning off your console, with infinite active camouflage. This makes the Campaign on Halo 2 considerably easier, even on Legendary difficulty.
 * In any Halo game, when you have active camouflage on and you get in a vehicle, the camouflage stays on and appears as if there was a ghost driving it or that it was driving itself (works particularly well with the Warthog LAAG). It works with any vehicle that the player is visible while driving.
 * In Halo 2 for Windows Vista, when playing on Threshold, your comrades are not picked up by radar when camouflaged.
 * The lights on a Gravity Hammer can be seen clearly when camouflaged. It is not recommended to have a Gravity Hammer either as your primary weapon or secondary weapon when using active camo, as the lights make you an easy target for experienced snipers.
 * In Halo 3, go in Monitor mode and find an Active Camouflage. Go inside it. After about 10-20 seconds, the Active Camo will stop making its shimmering noise and you'll hear a brief whispering sound (like a sigh or breath), and then it will continue its shimmering noise.