The video chips in several classic consoles from the ColecoVision through the Super NES all output pixels at 315/88*3/2 = 5.37 MHz. At this dot rate, the BT.601 clean aperture* is 280x240 dots, making each dot an 8:7 rectangle (source).

The right triangle with legs 1 and 2 units has a hypotenuse √5 = 2.236 units, and the smallest angle θ is arctan(1/2) = 26.565°.

Code: Select all

```
_,o
_,-' |
_,-' |
_,-' θ) |
o-------o-------o
```

Code: Select all

```
\
\
\
_,o
_,-' |\
_,-' | \
_,-' θ) | \
o-------o-------o
```

How much smaller? For an angle with tangent t and cosine c, it is a trigonometric identity 1 + t² = 1/c². But the above triangle was designed such that tan θ = 1/2. So if the hypotenuse of the above triangle is 1 unit, the long leg is 2√5/5 = 0.8944. This is just 2% longer than 0.875, the height of a scanline in pixel-widths. So at this angle, 16 pixels to the right, 16 pixels up, and 8 pixels front to back represent very close to the same distance.

And this is how the viewpoint works in a lot of "isometric" games for these consoles, such as

*Snake Rattle 'n Roll*,

*Solstice*, and the Genesis version of

*Viewpoint*.

Should I also run the analysis for a different angle that might work better for the 320x224 mode of the Genesis and PS1 (clean aperture is 350x240) and quarter D1 (352x240)?

And this is what I came up with in Blender:

* In before kyuusaku mentions pre-BT.601 standards.