Spring RTS Engine

So, I have a map where I change the heightmap completly, and it makes the planes fly underground, presumably because they follow the old heightmap.

As I was about to create a bug on mantis to complain about that, I first searched if it wasn't already reported, and found http://springrts.com/mantis/view.php?id=1805

tvo wrote:0001805: smooth mesh isn't updated when map is terraformed
Description According to MadrMan, planes with useSmoothMesh can fly through land when land is terraformed.

[13:02:13] <MadrMan> probable bug found
[13:02:23] <MadrMan> planes fly using the smooth mesh thingy right?
[13:02:33] <[RoX]Tobi> if that is enabled, yes
[13:02:41] <[RoX]Tobi> (it is by default)
[13:02:48] <MadrMan> in CA you can make hills
[13:03:00] <MadrMan> planes fly right trough the hills

imbaczek wrote:yes, that's by design (for now). probably should figure out a good (== fast) way of updating the smooth mesh on heightmap change.

currently you can work around it using lua smooth mesh support. (not documented anywhere except commit messages, as is spring's tradition )

So someone please explain Lua Smooth Mesh Support.
- What's the smooth mesh, is it used for anything else that plane fly path, what resolution is it, any way to display it for debug purpose, etc...
- What are the lua command to manipulate it, their name and argument, any quirk I should know about them, etc...

he said you should check out the commit messages.
you can easily search in them with gitk, for example.

http://springrts.com/wiki/Lua_SyncedCtrl#Heightmap

Thanks Kloot.