All scene's in MercTactics are generated randomly.
Previously, I've just "sprinkled" stuff into a scene randomly, but this doesn't look very good. Stuff tends to be clumped together in the natural world.
So, I used a Perlin noise map to control the placement of plants and rocks.
In fact, for the rocks I use two perlin maps, one to control size and one to control colour, because rocks of the same colour tend to be clumped together as well.
I use a less detailed perlin map for tone, so the colour changes more gradually.

Finally, I use a third Perlin map to control the placement of grass, weed and trees.
This is how the complete scene turned out: