Input for GrassLandscapeOutput

Hello, I am trying to connect a noise map in the Input of the Grass Landscape Output Node.
I tried to create a world aligned texture, to control the texture by an absolute world space and by a Landscape coordinate. Anything I tried failed. The grass were generated on the black and the white parts of the map.

How can I connect a custom map to control the grass generation in a Landscape? Do I need to use LandscapeSample only? Or does it exist a technique to use custom noise map?

Thank a lot for your suport,