Heads-Up Display

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".

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 visibile 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.

If it's the first person view of a robot, or otherwise mechanical being, then you're looking at Robo Cam. When it's actually part of the game environment, it's a Diegetic Interface.

Examples of Heads-Up Display include:

Anime and Manga

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.

Film

In The Living Daylights, James Bond's Weaponized Car has these for aiming its missiles.

Video Games

Most combat flight simulators will naturally at least try to emulate a real-life military-style HUD.
- The 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.
- In 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.
Just about any game with Powered Armor will have a diegetic HUD justified by being overlaid on a helmet visor. Following examples include:
- Halo. Especially notable in that from Halo 3 onward, the HUD loses its curvature when the camera goes third-person.
- 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 also had 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' 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 in some; you can disable the effect by toggling the "HUD Lag" option in the menu.
- 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.
- Azraels 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.
- 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 HU Ds where you can actually see the inside of your helmet.
  - Another 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.
- 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 Hammerspace.
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.)
In the remade Battlezone 1998 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.)
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.
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.
- Deus Ex Human Revolution does away with the elliptical shape, but is still very much diegetic as one of the protagonist's numerous augmentations. The HUD even flickers at first until you get Pritchard to fix it.
Mechwarrior 3's HUD would get more fuzzy as your ;Mech took more damage.
- On the same note, Mechwarrior 4's HUD got fuzzy when the 'Mech was overheating, would turn off if the 'Mech shut down, and went into Interface Screw mode and became nearly useless if you mech suffered a blow to the cockpit.
- This also extends to Virtual World BattleTech in the arcades, with the various MFDs actually losing vertical hold (they're CRT-based) after a heavy hit.
Echelon's HUD would partially disappear when entering enemy disabling fields.
F.E.A.R.'s interface would flicker in response to supernatural happenings.
- In F.E.A.R. 2, the HUD is part of the players combat eye wear and vanishes when they are removed.
The Naval Ops series uses a HUD that covers most of the screen. Most of it is a radar that shows enemies close to you; the rest indicates things like speed and heading and whether anything is horribly wrong with your ship (like a torpedo taking out your rudder). It can be a little hard to read if the enemy spams missiles or torpedoes.
In Marvel vs. Capcom 3, the HUD is used as an offensive weapon by Deadpool, natch.

Western Animation

After Kim Possible's mission outfit got ruined in "Clothes Minded", she tried a series of replacements, including a spacesuit-like contraption built by her dad. Unfortunately, when he installed the heads-up display Kimmunicator in the faceplate, he overlooked that "must under no circumstances interfere with the operator's view beyond the panel" thing. Even more unfortunately, Wade called while Kim was in the middle of fighting Shego.

Real Life

A number of Apple applications (the most common being Xcode and iMovie) use HUDs in lieu of right-click popup menus for certain functions. Implementing them in non-Apple apps, however, is a somewhat ad hoc process...