Hey everyone, I’ve been working on a project to expand the West Coast USA map. The goal is to finally open up that highway that’s been under construction, add another city, some more mountain roads, and just expand the map in general — give players more to do, explore, and eventually tie it into career mode progression. Think of it as “West Coast Plus.” Since I’ve had a bit more free time recently (got laid off last week), I’ve made some solid progress. I’ve expanded the terrain, got the heightmap loading and working fine, and I can sculpt or paint new land past the existing backdrop. But I’ve hit a wall when it comes to terrain layers and splatmaps. Right now, grass is showing up all over the roads and the terrain paints didn’t carry over properly when I expanded the map. I don’t have access to the original RGB channel data from the splatmap, so recreating those materials has been difficult. I’m not even sure I fully understand how the splatmap system works under the hood. What I’m really trying to do is keep (or accurately recreate) the original painting — like asphalt where the roads are, grass on hills, dirt in alleys, and so on. I want the new terrain to blend naturally into the existing one, match the backdrop eventually, and preserve the “feel” of West Coast USA while giving it more space and variety. But without working terrain masks, I can’t start building the expanded city, new highway sections, or anything else — so this problem is kind of holding the whole thing up. So I’m hoping someone might be able to help me figure out the best way to move forward. Is there a proper way to extract the terrain masks from the current West Coast terrain? Are the RGB channels from the splatmap actually used to control material layers, and if so, is there a way to recover those? If not, should I just repaint the terrain layers manually using the F11 editor? And is there a clean way to prevent materials like grass from bleeding into asphalt regions in the first place? Also, when expanding terrain, is it possible to project the old layer data onto the new heightmap somehow, or do I just have to start fresh and try to match it visually? This stuff’s a bit outside my wheelhouse — I’m more comfortable with 3D modeling than terrain work — so if anyone has advice, tools, or general workflow recommendations, I’d really appreciate it. Thanks for reading.
