Yet the term Isometric is the most commonly used, as it suit for most of those pseudo 3D games, so we'll use it as a whole, despite sometimes unproperly.
==Inaccuracy on old school Computers==
The isometric and most parallel projection originate from engineering, Architecture, design and technical drawing. As such, they have a theory and precise specifications, and own a lot to the work of Gaspard Monge, a French Mathematician from the French revolution era. However due to the pixelised nature of bitmap graphics and Cathode Ray Tube display, also due to the un-regular aspect ratio of pixels (which depend on the videomode, the screen/Monitor used, but also the colour displayed), Parallel projection's types can't be really accurate due to variation and approximation in axis' scales. Those term's use are then mostly indicative. The global term is '''parallel projection'''. But in common language we often talk indistinctly about Isometric... ==Types of pseudo 3D"Isometric"==
The global term is parallel projection. But in common language we often talk indistinctly about Isometric...
There are actually 2 families : symmetric and asymmetric parallel projections.
*Symmetric : the X and Z axis form an equal same angle with Y axis.
*Asymmetric : X and Z axis form different angles with Y axis.
Used parallel projections are often ====Asymmetric :====
X and Z axis form different angles with Y axis. *'''"Horizontal" Oblique /Trimetric projection :''' [[Pac-Mania]] obviously, yet "Beat Them Up" games (like Double dragon or Renegade) or even few "Shoot them Up"s (Mag Max) do use some kind of this.
**In those case, we can talk about '''Perspective Cavalière (F) / Kavalierperspektive (D) / Perspectiva caballera (E)''' (is there en English equivalent) which is a perspective with unchanged 2D vertical and horizontal and a 3rd Axis in oblique. This specific projection enable to keep the 2D gameplay based on vertical and horizontal movement.
**As told, the scale of each axis can vary greatly.
*In rare case, the X axis is not "horizontal on screen. **as seen in Crystal castles (US Gold) ====Symmetric :==== The X and Z axis form an equal same angle with Y axis *'''Isometric projection :''' [[Head Over Heels]] is the most well known. it may not be real isometric because it is quite difficult to get the Y axis on the right scale, and those are probably more Bimetric projection actually close to isometric.
** Backgrounds or graphics in such projection are easily obtained in Mode0 as it need an oblique matrix with a scale of 1vertical for 2 horizontal. Sadly the blocky pixels of Mode0 don't enable to do finely detailed sprites
*'''pseudo isometric :''' those are symmetric parallel projections with angles for the X and Z axis which suit the Pixel ratios, hence producing harmonius harmonious and regularly shaped lines.
Some "Mode1" isometric, X and Z having 45µ° 45° angle with Y.
the diagonal ratio is X1 for Y1.
*1x1 is better for horizontally limited display.
*4x1 is better for vertically limitade limited display.
==Masked Sprites and Elements==