Originally a military technology, a Heads-Up Display is a device which projects supplemental information onto the surface reflection of a transparent panel. This allows the user to view the projection, or view objects beyond the panel without moving his head. The system is a compromise between limiting the user's field of view and forcing him to look away from his primary display to view additional information. Fighter jets use these systems to show targeting information. Systems using this technology are sometimes called "Augmented Reality", though that term has become increasingly associated with entertainment products in the 21st century.
In the real world, most uses of this technology remain military, though some car manufacturers use these displays to show dashboard indicators. They're also becoming increasingly common on airliners and other civilian aircraft as well.
Though very different technologically, the term is frequently used in the context of video games to describe a style of user interface where supplemental data is overlaid directly onto the main window rather than being separated into a different display panel. This allows the main window to occupy the entire viewport of the game. The name probably originated with the fact that the earliest uses of this design were in flight simulators, where an actual HUD was being emulated. A video game HUD may be diegetic, meaning that it is actually part of the in-game world and visible to the character (more common in sci-fi), or just for the player's benefit. A real-world HUD must under no circumstances interfere with the operator's view beyond the panel. In videogames this constraint is relaxed somewhat, since you can hardly display information outside of the monitor or TV screen (unless a second screen counts...).
You will be shocked to learn that HUD has nothing to do with the Paul Newman movie of the same name, which is about a ranching family. The United States' Department of Housing and Urban Development is right out.
- In Code Geass, the Factsphere Sensor (which is essentially an advanced thermo-camera) works this way, providing extra information to the pilot's cockpit screens. A miniaturized version is used by Britannian soldiers in their helmets (as seen with Suzaku's helmet display in episode 1), and is compared to a HUD in the wiki article.
- Scouters in Dragon Ball Z.
- Project Itoh: Genocidal Organ. The Super Soldiers take eyedrops of nanomachines which overlay the required information on their vision.
- The lenses of Batman's cowl have the ability to show him certain things in a head's-up-display only visible to the wearer, prominently shown in the Batman Cold Open of Batman: Hush. The other Bat-backed and supplied Gotham vigilantes also have them.
- Robin Series: Jaeger's goggles have a heads-up-display through which he can control his drones in order to spy on and follow his prey. It also helps with targeting.
- Iron Man: Starting with the "Mark II" armor, the suits built and worn by Tony Stark in all the three films and The Avengers. There are both POV shots of it and shots inside the helmet where it's projected in front of Tony. It starts to flicker and fail when he takes damage. It completely disappears when faced with the icing problem in the first film and when it's travels into space in The Avengers.
- The Living Daylights: James Bond's Weaponized Car has these for aiming its missiles.
- Mission: Impossible Ghost Protocol: The concept car driven by the IMF team has a road map displayed on the windscreen as they race to stop The End of the World as We Know It, and even warns of pedestrians crossing the road.
- Star Trek Into Darkness: Kirk and Khan space-jump in suits with HUDs to guide them—until Kirk's helmet gets hit by debris and the display fails.
- In Stark's War, all American troops have complicated electronic displays in their Powered Armor. Some of this is useful, but some of it is widely detested, because it exists to harry soldiers into exact obedience to the overall mission plan, regardless of the reality on the ground. Military command always assumes that their plans will go like clockwork, and yells at soldiers for getting even slightly behind their pre-programmed timeline. Heaven help the soldier whose HUD starts to show orange or red numbers on its clock instead of the approved green.
- A Star Wars example is in Legacy of the Force, where Karen Traviss is more than a little obsessed with the HUD inside Boba Fett's helmet. Unsurprisingly, she's the one responsible for those awesome guys from Star Wars: Republic Commando (mentioned in the "Video Games" section) being more than just one-off characters.
- in No Such Thing As Werewolves Mohn Corps issues it's higher ranked soldiers shades that provide them with a tactical HUD.
- Absolute Zero had an interesting justification in its fluff for the HUD, and even for the 1st-person cockpit graphics. Instead of actually having windows or internal displays, the pilot cabins and such in all of the vehicles are windowless and featureless. Instead of windows, the pilot wears a VR helmet, which is fed by cameras and other sensors to make a composite of the world outside the vehicle. To keep the pilot from being disoriented, a virtual cockpit with windows and instruments is inserted into the augmented reality.
- Ace Combat series models HUDs for military fighter planes on the actual fighter planes. However, the ability overreaches, as the player is able to see targeting boxes around enemy targets at any point in the cockpit, not just through the HUD. This include third person perspectives.
- Over G Fighters: The HUD may be toggled (as a view mode) between Ace Combat style and a realistic HUD where all of the information is displayed on the transparent panel.
- Azrael's Tear also outfits the Player Character with a nifty suit of Powered Armor, and the HUD will even visibly list off its attempts to resuscitate its wearer in the event of death.
- In Crysis, the player's entire view is apparently electronic, and is distorted by close proximity to aliens or a near miss with a gauss rifle. The HUD itself has a loading screen that is shown when the suit is activated. It can also be disabled by a disruption grenade in multiplayer, removing all of its functionality.
- In DOOM (2016) the HUD is explained as being a function of the Praetor suit, and visibly displays functions such as calibration, impact compensation, tether installation and indicating low health.
- Dead Space: is an unusual third-person example with no HUD at all. The health meter is represented by the lights along the back of the character's suit, remaining ammo in a gun is shown through a display on the gun itself, and the inventory display is actually projected by the character's suit, with the protagonist looking at the various item boxes and physically pointing to the item he wants to use. The point of the latter is debatable, since the items are kept in Hammer Space.
- Entering a suit of it in Fallout 4 will transform your HUD into a Diegetic Interface, with your ammo counter in a corner of the helmet and your AP, health, and Geiger counters as gauges along the bottom edge. In addition, there's another gauge tracking how much charge is left in the fusion core powering the armor, and a small screen off to the side tracking your armor's condition, with parts needing repair highlighted in red and missing/broken armor parts blank. Your Pip-Boy menu, which usually brings your wrist-mounted Pip-Boy up to your eye level when you open it, is now a window that pops up on your helmet's HUD. Also, your Pip-Boy flashlight (which provides illumination by brightening the Pip-Boy's screen) is replaced with a built-in helmet light, so if you're not wearing your power armor's helmet, you can't access either flashlight.
- Halo. Especially notable in that from Halo 3 onward, the HUD loses its curvature when the camera goes third-person.
- In the Half-Life series, the HUD is explained as being a feature of the HEV suit, hence why your hud doesn't appear until putting it on.
- All of the MechWarrior games have a HUD of some form to display information regarding aspects of your 'mech and enemy units.
- Metroid Prime's display is meant to be the HUD inside Samus's helmet. This is reinforced by the fact that the edges of the helmet's visor are visible around the borders of the screen, water or steam occasionally accumulates on the display, and certain flashes of light can actually cause the player character's reflection to become momentarily visible in the screen, making Samus one of the few FPS heroes to have reaction shots. Metroid Prime 2: Echoes even includes an enemy that can crash Samus's computer systems, causing screen updates to become jerky, random letters to scroll up the screen, and weapons to be disabled until you "reboot" with a button command.
- Metroid Prime 3: Corruption also has occasions where the visor can become distorted, which can either be temporary or is solved by switching to a different visor mode. And some enemies can latch onto Samus's helmet, obscuring her view.
- The helmet even has a slight delay before turning with the player to simulate being a distinct object from the player's head. Apparently this causes motion sickness for some players; you can disable the effect by toggling the "HUD Lag" option in the menu.
- Star Wars: Republic Commando also has the HUD as the electronic display inside the player's helmet. EMP grenades can disrupt this or cover the screen with noise. Most awesomely, the front of the helmet has some sort of energy windshield wiper that cleans your HUD of obstructions - usually splattered blood from an enemy after a punch-dagger to the face. It's also probably one of the only HUDs where you can actually see the inside of your helmet.
- Deus Ex: Invisible War had a somewhat eyeball-shaped elliptical HUD, so that it would seem more like it was projected over the agent's vision. Due to clunky design, the gimmick went over poorly with players of the last game.
- Elite: Dangerous has a display like this, marking out important objects like stars, planets, orbital space stations, navigational beacons, and other information like gravitational orbits on the glass of the canopy. It's worth noting that this is an In-Universe mechanic; if you break your canopy, you'll have to navigate to the nearest space station via whatever glass fragments remain.
- Space Hulk: Deathwing does this, with a unique little detail. Every other minute or so, your suit's displays will flicker and glitch a moment before rebooting themselves. It's a clever little nod to the fact that the Terminator Armor you are lumbering around in is magnatudes older than the already centuries old Space Marines inside them, and the inner workings are showing their age.
- In the remade Battlezone games, which have more in common with Command & Conquer than the old vector-graphics Battlezone, all commands and build orders are given through HUD sidebars, much as using pre-made text/voice responses in modern-day FPSes like Unreal Tournament. They ARE a little more action-y than the standard RTS hybrid, so this is to be expected. (though you can give orders you are also fighting on the field, and randomly snagging enemy craft when the mood hits you.)
- Chantelise: The HUD shows currently equipped items, a Life Meter, a Mana Meter and a Level-Map Display.
- The computer games in the Command & Conquer series are supposed to take place on a computer controlled by a remote commander. Allies, hero units, fellow commanders, and enemies will often contact the player by video and be displayed to a portion of the screen (often the area containing the map - which is only available when the radar is working.)
- Echelon's HUD would partially disappear when entering enemy disabling fields.
- Fortune Summoners: There's a picture of your current character's face in the very upper left corner, and that corner holds your Mana Meter, your Life Meter with current Hit Points, and your Experience Meter. The lower right shows enemy information. Basically what enemy is currently being targetted, and how much life they have, via a Life Meter.