I'm always playing around with maps, even if I rarely post anything besides textures. One issue I'm trying to figure out is how to size a diffuse texture as an overlay. I've done it successfully on one map. I created that map from a 1024 heightmap and used a 1024 DDS file as the diffuse texture for the terrain materials. This is the texture and the resulting map: I tried it on another map. This one is much bigger, 8192. (It's a real-world location I'm rendering at real-world scale.) This time, I had already imported the terrain using masks for grass, forest floor, ice, and rock. I left the rock and ice textures alone because I wanted the cliffs and snow line to stay the same, but added the overlay map (8192 DDS file exported from Gimp the same way as the badlands map above) to the grass and forest materials by editing the main.materials.json in the art/terrains folder. I set the diffuse texture size to 8192. The result was originally a black field where I had speficied the overlay image, including after exiting and reloading it, but when I went back to it tonight (after writing everything before this paragraph), the overlay texture was there--but 1/2 the desired size. So now I'm playing with texture sizes again to make it work. And I've got it. For anyone else having this problem: The overlay texture has to be the size of the terrain, including any multiplier you have used to expand the terrain when importing the heighmap. I imported a 8192 heightmap with a 1.5 m/pixel multiplier. In the editor, the Base Texture doesn't seem to accept any value over 4096. Editing the main.materials.json in the art/terrains folder, I set the size of the diffuse map for grass and forest floor (the textures I wanted to have the overlay) to 12288 (1.5 x 8192). The result: Now I've decided I don't like the ice texture as a snowline, so I'm going to change that, but hopefully my stream of consciousness tonight will help someone else trying to figure this out. Happy modding!