Careful now, too much discussion on this point, and you'll invent a new compression algo.

There's a correlation but it's not a dependency.

A woman with very small breasts won't have the tissue volume to have nipples pointing at certain angles, but in average to large sized breasts, they point in many different angles. It's more dependent on tissue density + how self supportive the breasts are.

I'm a bra fitter. I look at a lot of boobs.