Load a simple grey shaded material. This is how the mesa with castle imported looks.
We want to have eco-paint grass over this mesa in specifics areas (the flat level areas where grass would grow easily.
To easily figure this out. We’ll load a new map to our material. Switch from Procedural to Mapped picture.
We’ll use a uv grid map. This will help us figure out what regions we want to have our grass grow.
Load this image file to your material.
Now your material is using the uv grid.
Here you can see how the uv grid lands on your mesa.
Here’s a down view of it as well.
Here is a black and white image we’ll use as our map for the grass. I created it in Maya using a 3d snow shader. Basically the snow (white) would only land on areas flat enough to stay on it.
Now if we place our UV grid image behind it. You’ll see where the snow is going to cover on our mesa.
We can now add our ecosystem. Under Simple material, switch to add an EcoSystem.
It will add an additional layer into your Material.
Now multiple tabs are created with the Ecosystem. We’ll only care about General and Density for now.
In the General tab, we’ll find the “Patch of Grass” plant species to populate our mesa.
Change its scale to 20 for our scene’s size.
Now go to the Density tab. Click on Variable Density and right click on grey sphere. Choose Edit Function.
This opens the Function Editor. All we care about is the Density node and clicking on the “Projected Texture Map” node.
Hook up the Density to the Projected Texture Map, by grabbing the left round button on the Density node and dragging it to the other node. A pop-up appears, select grayscale output.
Select the Project Texture map node. Now below we will load in our mask.
Find our mask.
Once loaded you will see an icon of the mask applied.
Now we can do a render. (I made my density percentage to 83%).
And aerial view
Now you can trim your snow mask if you want to conserve memory and render time for your shot’s specific coverage. Just paint out area we don’t see to be pure black.
This same technique can be done to add more populations like trees, shrubs, or rocks for example.