I understand the basic idea of multiply and add maps - they make it harder to notice the texture repeating itself when tiled over a large area. What I don't understand is what each image does and how they should be made. I've looked at the maps for the default grass texture and I can see that Multiply is a greyscale image. How it should be made for best results? Should it be based on the Diffuse texture (if so, how?), or will any greyscale image suffice? Is it correct that grey pixels in the Multiply map lead to the pixels in the Diffuse map being lightened/darkened? I've looked at the default grass texture and the multiply map uses very light shades of grey. Is it the case that darker shades of grey would really hide the tiling effect but would also make the texture really dark, so a compromise must be made by using lighter shades of grey to disguise the tiling to some extent but still allow the texture to be seen? And what does the Add map do? In the default grass001 texture, it's mostly transparent, and what little opacity is there is too hard to see.