Is there a way to spawn meshes on other meshes based on the colorchannels of a texture?

Hi all,
I hope this is the right place to ask such a question.

To the problem:
What we have:

  • StaticMeshes, 1km * 1km, with textures
  • Textures, that define by their R,G,B channels which trees should be placed where on above mentioned Meshes

What we want:
A possibility to spawn different sets of meshes on places defined by the RGB-Textures.

I’ve been looking for a way to do this for a while now and wasnt lucky so far. Most problems revolve around landscapes and foliage, but because of the nature of our data we can work with landscapes. Another problem (The reason we dont handpaint this) is, that the area where foliage would need to be placed is huge (100km*20km).

Thanks in advance for taking the time!