That'll probably be part of my problem, I'm using stable gimp, To answer your first question nothing, importing into gimp, the problem is even i think blender is still exporting 8bit, idk why, but i get a similar effect if i import the height map into gimp and export it, and as you mentioned gimp stable, is 8 bit, that's only half of my problem, I changed the 8 to 16 in the render settings but for some reason it must be saving it as 8, I can't say for sure.
You need to have 16 bit selected in both the render settings and when you actually save out the image. And yeah as soon as you open a 16bit image with stable you'll be looking at an 8bit image. There are some experimental versions floating out there that function, Partha has one that'll get the job done (although it's a little slow).
You can, with beam 0.5.x and above, use the new terrain editing functions to line up terrain with Mesh roads, to make smooth decal roads. Laying out mesh roads as you would want your decal road to be in the future, then setting the 'raise and lower' terrain tools on it, will line up the terrain surface with the surface of the mesh road. You can use the opportunity before smoothing your terrain to the mesh road surface to bank the road, or make it extra-wide (like 2~3x the width of your intended decal road) so that smoothing the roadbed and THEN the road's edges will be easier for you. You don't need to use the carve tool, but the 2nd and 3rd last tools inside the terrain editor. It comes out really sweet, and I did almost all my roadbeds in Tennessee, USA map this way to great result! Although I guess you could still use blender like this article instructions, you aren't required to now. You can usually do a few miles in the space of an hour, or spend all evening and get 10~20 miles done, depending on how fast you work.
