Thermal imaging is the use of special cameras that see in the far infrared electromagnetic spectrum (i.e. heat). Newer equipment can highlight objects that are warmer than the ambient environment — most often people and vehicles with their engines running.
Infrared radiation can pass through materials that visible light cannot, like dust clouds and fabric. Smoke from white phosphorus sources can screen in the infrared region as well as the visible.
Various weapons may also rely on guidance via thermal sensors. However, these can often be spoofed with flares, especially if they mimic the heat signature of the vehicle they are meant to protect.
Thermal imaging is heavily used in Battlefield 3, with various weapon accessories and vehicle upgrades allowing their users to see in infrared. Other upgrades are available to mask the heat signatures of certain vehicles.
Using an IRNV scope or Thermal Optics, players can more easily see silhouettes of enemy infantry and vehicles. Certain gadgets also give off heat when deployed, such as Anti-tank mines, Radio Beacons, and Micro Air Vehicles. However, the IRNV scope underwent a patch making it much less effective than previous or compared to Thermal Optics.
There are two types of thermal imaging in Battlefield 3. The vehicle mounted thermal imaging features the "white hot" imaging while the infantry-mounted IRNV scope features green monochrome night vision with an additional "orange hot" overlay, as seen in the picture above.
Thermal imaging equipment and optics reappear in Battlefield 4 with similar function to their Battlefield 3 counterparts.
- Strangely enough, in Battlefield 3, Thermal imaging marks the ammo crates and destroyed vehicles as orange, even though they do not have any heat signatures.
- In the mission "Thunder Run," the player's tank uses the "green-tinted" thermal imaging found on the infantry scopes rather than the "white hot" type used by vehicles in multiplayer.
- The Dropship does not have a thermal signature at all, it can however be locked by heat-seeking weapons like normal.
- The vehicle wreckage between the Treatment Plant and the Farm on Armored Shield give off thermal signatures. This design choice is carried on to Battlefield 4, with various wrecked vehicles having a visible thermal signature.
- A late game patch to Battlefield 4 reduced the effectiveness of thermal imaging, making it almost impossible to see through smoke. Despite being its intended purpose, DICE acknowledged that gameplay would often devolve on gamemodes like Rush, where players that had received thermal optics (either by random Battlepacks or higher-level progression with vehicles) and utilized smoke would often have a significant advantage.