revisiting maps - Can levels be changed?

[HarryInk]

I built a pretty little map with fingers of a hill reaching down into a river valley.  Problem is the hills are about 150m high, which seems excessive.  Looks great but is a little over the top.

Is it possible, once the map is made, to revisit the levels and reduce them? 

My impression is that it is not.

[bibouba]

yes if you scilab.

You can put the new file highv4 in the map.