different splat maps in gray level

Hello,

I work with Unity and I test world machine for terrain creation.
I use the RTP plugin but I have a problem.
To apply different textures, I have to have several splat texture map in gray level.
I tried the height splitter, but the result is not good.

How should I do?

thank you;)

http://img15.hostingpics.net/pics/185286print2.jpg