So yeah, I work'd around this a little bit. What I wanted was heightmaps of LineIIage terrain. Thing with 16bit color didn't work out, so there are the steps I followed to get it -
Download 3D Ripper DX and launch lineage with it.
*Select "export as .obj".
*If you are using windows - disable UAC, because you will get "Unable to create process" error.
Go to the place which you want to rip and press F12. I'm not sure why, but 3rd person view does not work out well, because ripped meshes will be tilted. So use first person view (this method wont get you wide field) or better - use "//camera on" GM feature, to get free camera and ability to zoom out great distances.
Then import your mesh to 3ds or your preferred editing tool and delete unwanted objects (as in this case - city envitoment, trees, rocks, etc.) What you will be left with is terrain mesh.
I look'd up fastest way of converting mesh to heightmap picture and found out this article -
http://forum.world-machine.com/index.php?topic=2439.0There is a video tutorial how to do it.
So in the end you are left with heightmap picture of lineage2 terrain which you can import anywhere.

*have in mind that i'm complete noob in this field, so try it yourself before asking serious questions, because probably I wont be capable of answering them

. Thanks! Cheers!