Hi miklkit

I think you have to put 0 were it asks you your gpl rank.
If you want to change the values in a horizon 3do, is quite simple using GPL Editor.
You open the horiz.3do and scroll down to SZYX "XYZS";
here you find all the xyz values for every vertex ( they are around 25) if you double click on one of them, a window appears and you can change the values as you wish.
You basically have to change the Z value for the amount that you think is right ( obviously values around thousands will be the top of the box and values around negative hundreds will be the bottom).
Is a pretty quick work. You can add or subtract let's say 300m to every Z value in a couple of minutes.
Hope it helps
