I recently saw a game dev youtuber give out bad info when asked what a splat map is, saying that “the splat map is the base texture that covers the entirety of the terrain. The texture map (image) is literally placed (splatted) over the terrain (in the video a satellite image of several city blocks was placed unceremoniously onto a plane).” This, as I understand it, is incorrect.
A splat map color codes information for the purposes of terrain detailing. Typically the colors will inform texture placement and layering/blending. Most often they contain 4 channels, RGBA, with each channel corresponding to a different texture slot.
Simply put, it’s a color map where each color corresponds to a different texture. Why bother? It allows you to swap textures in and out and see the results. The process is a bit antiquated now, as most software allows you to slot textures without using a splat map middle-man.
Previously I used Terrain Toolkit to procedurally generate my splat maps according to height and slope data. At some point I’d like to play around with World Machine. If I remember correctly, there is a workflow involving World Machine and Marmoset Skytools that is linked through a shared use of splat maps. But again, this was some time ago and there are probably more current solutions. If you have a preferred workflow, please let us all know in the comments. Thanks!