Putting some information here in hopes that it helps someone in the future. We are using a custom version of UE5 based on 5.1. I had a coder I work with take a closer look at this. This appears to be a problem in the rasterization of the geometry of the spline to the heightmap, possibly a bug in the triangle rasterizer. The simple rasterization that UE5 uses now won’t work for anything more than just gentle curves and definitely breaks down fast with any kind of banking curves. This is the type of problem I started with:
We are now adding another subdivision on top of this. Getting better:
This also seems to address another issue with problematic road offsets that I mentioned in another post here. Road collision and spline seem much closer now:
