Hi PaQ,

> As far as every uv islands have the same ratio (so no
> stretching/scale difference between every uv's island).

Stretching won't really be possible to totally eliminate if the surfaces themselves compress or squish.

But in relation to one another the way I was thinking would be to do it by surface area of the 3D polygons.

So for instance the corner patch in a filleted box would get a smaller UV area than a larger sized piece.

- Michael