How to create low poly terrain properly?

I recently started learing UE4 and blender to create my own game, which means I know almost nothing atm. Since I want to make most of the stuff myself (both graphics and code), I decided to go for lo poly since it saves alot of time. I already made some floating island, trees, houses ect and exported them to UE4 which worked out very nicely, but now I’m facing a question I can’t find an answer to:

I wan’t my game to be set in a single but huge world, how do I create the terrain? Do I split the terrain and import it region by region (which would end up in weird looking region borders)? or do I create a big blender file and export it all at once? (last time I tried that my pc lagged out and I had to restart).

I don’t want my world to be generated but preset. How do I do that?

How large it must be in km?

You can use UE4 built-in landscape system, and achieve low-poly stylized look in landscape material. This will not work on mobiles though.

What your looking to do is intermediate level id say, but the route i would take to achieve it is to:

  1. create a static mesh in blender of the terrain that you want
  2. separate the mesh in blender into smaller bits (think areas or Zones)
  3. Export the meshes from blender and import into Unreal Engine.
  4. use level streaming / world composition to dynamically load areas.

The following link could be of use.
World Composition Livetraining

Another thing you could try is to make a mesh in blender then create a heightmap derived from that mesh and use the heightmap to create the landscape in ue4.

Hope that helps a bit. Good Luck