Why is forward=down mouse orientation commonly called “inverted”?

Question

If you look at 3D games that allow you to control the camera using the mouse--most notably first-person and third-person shooter style games--you'll usually find two specific details:

• By default, pushing the mouse forward makes the camera look up, and pulling back looks down.
• The option to reverse this (forward=down) is called "invert Y axis" or something similar.

I've never understood that, and it's always seemed backwards to me, to the point where I get wildly disoriented in any game with default settings on. It seems intuitively obvious that the mouse (or, even more so, a thumbstick, which even looks kind of like a head sitting atop a neck) is modeling the perspective character's head. Move left, you look left. Move right, you look right. Push forward, the head pushes forward, and you look down... right?

In fact, this orientation was the default in a lot of early 3D games, such as flight simulators, MechWarrior 2, etc. But at some point it changed, and people started calling the intuitive orientation "inverted" and disabling it by default.

Are there any historical reasons behind this reversal of the default camera control orientation? Any articles, perhaps, on the rationale behind changing it, or studies showing why it was a desirable change to make?

Answer 1

It seems intuitively obvious that the mouse (or, even more so, a thumbstick, which even looks kind of like a head sitting atop a neck) is modeling the perspective character's head.

Maybe this seems intuitively obvious to you, but not to everyone. To some it would seem intuitively obvious that moving the mouse "up" should move your view "up." I'm not suggesting either side is more correct--they both have their followers obviously--but they're certainly both within the realm of reasonable possible interpretations of what the mouse should do. Apparently you're in the minority, since your inclination received the "inverted" naming, but somebody had to.

You requested some history. There's this from Wikipedia:

After id Software's Doom, the game that popularized FPS games but which did not support vertical aiming with a mouse (the y-axis served for forward/backward movement), competitor 3D Realms' Duke Nukem 3D became one of the first games that supported using the mouse to aim up and down. This and other games using the Build engine had an option to invert the Y-axis. The "invert" feature actually made the mouse behave in a manner that users now regard as non-inverted (by default, moving mouse forward resulted in looking down). Soon after, id Software released Quake, which introduced the invert feature as users now know it. Other games using the Quake engine have come on the market following this standard, likely due to the overall popularity of Quake.

And here's a fun video of someone who agrees with you.

Answer 2

If you stop calling it "pushing forward" on the joystick/mouse, and start calling it "pushing up" (which is the way that most players think of it -- particularly the ones who don't play flight simulators), then the "invert Y axis" name makes complete sense, since pushing up causes the player to look down.

Edit:

The fundamental issue here is people's mental models about what a game's controls do.

One group of people have this mental model: "if I press up, I should see more upward". That is, the controls are wired to the view, and what I do with the controls should have the same effect on the view.

Another group of people have this mental model: "If I press up, I'm swinging the camera upward, so I see more downward"; that is, the controls are wired to an object in the world, and the rendered view is merely a side-effect of the motion of these controlled objects in the world.

Neither viewpoint is 'right'. Lots of games have been made using each approach, and these days they mostly give you the option to switch it if you don't like the default. Mostly people have settled on "up means the view moves up" as "normal" and "up means the view moves down" as "inverted", but there have been plenty of games which named them in the reverse direction.

Incidentally, the same issue exists for left and right, for games which have a third-person camera. Some people think that pushing left means they should see more to the left, others think that pushing left means that the camera should swing to the left, and thus they should see more to the right. Some even feel differently about the two axes.

The important point is that options are presented to players, which lets everyone play according to their own preferred mental model, rather than obsessing over which approach is the correct one.

Answer 3

I believe the most likely explanation is that it's an artefact of the original Quake, which defaulted it's mouselooking to forward = up, and had a menu item explicitly called "invert mouse" for forward = down. See e.g. http://en.m.wikipedia.org/wiki/Mouse_(computing)#section_11

Also interesting to note that for standard GUI usage moving the mouse forward will move the pointer up on-screen, although I don't know how related that may or may not be.

At the time, true 3D was something new and strange and the best control schemes were still being worked out, so it shouldn't be surprising that the default used was the reverse of what many, if not most, now consider normal.