Question about map height levels

[dmnt]

I've been editing some maps from real terrain, but I'm a bit uncertain about the height levels. What is the hill height vs. real hill height factor? I've been using metric 1:1 ratio, where level 1 hill (Height: 10) is ten meters higher than the lowest map point, excluding water.

Of course it doesn't matter except in situations, when units could see over a forest to an opening or field, but I'm trying to get the map as close to real as possible still keeping the map playable in winspmbt.