Is their any way to increase the wireframe divisions in Unity’s terrain system? What I mean is, can you increase the amount of polygons in a terrain plane so that terrain sculpting is more detailed when working with a large area of terrain.
If it can’t be done, does anyone know if it’s possible to import a high poly plane from a program like Maya or 3ds Max and convert it to terrain and edit it in Unity?
you can change the resolution, but besides that no.
Also, you cannot import a plane and use it with Unity’s terrain editor. You can use it like a terrain, but you will have to do it by hand. Sorry 
Use this. But as Peter G said, you can just increase the resolution.
–Eric
Okay guys, thanks for clearing that up for me, I had already increased terrain resolution, because it’s so large the wireframe grid on the terrain mesh was incredibly far spread, meaning I couldn’t sculpt small hills and such as it would affect a huge area.