Isometric projection is a form of orthographic projection, or more specifically, an axonometric projection. It is a method for the visual representation of three-dimensional objects in two dimensions in which the angles between the projection of the x, y, and z axes are all the same, or 120°. For objects with surfaces that are substantially perpendicular to and/or parallel with one another, it corresponds to rotation of the object by +/- 45° about the vertical axis, followed by rotation of approximately +/- 35.264° [= arcsin(tan(30°))] about the horizontal axis starting from an orthographic projection view that is perpendicular to a face of the object. "Isometric" comes from the Greek for "same measure."
Isometric projection can be visualized by considering the view of a cubical room from an upper corner, looking towards the opposite lower corner. The x-axis is diagonally down and right, the z-axis is diagonally down and left, and the y-axis is straight up. Depth is also shown by height on the image. Lines drawn along the axes are at 120° to one another. The term isometric means "equal measure", which reflects that the scale along each axis of the projection is the same (this is not true of some other forms of projection). Isometric projection is one of the projections used in drafting.
Isometric projection is also used in many video games. Some notable ones include:
- Diablo and Diablo II: Dungeon-romping RPG games
- StarCraft: Science-fiction real-time strategy
- Clue: Murder at Boddy Mansion: the video game version of the board game Clue
- SimCity 2000, 3000, 4000
- The Sims: simulated people controlled by the player
- Several games from Ultimate Play The Game such as Alien 8 and Knight Lore
- Zaxxon: Early arcade space flight fight.