Heightmap Creation

I’m trying to create my first real heightmap (from an existing image). I read the documentation I could find about adding/using the heightmaps, but I didn’t see anything about what size they should actually be, or how to get rid of tile lines. Since I pulled these as satellite images first, I need to edit them now. My questions:

  1. I have an image - It is some size like 1900x1300. Do I need to make it square for it to tile nicely? If so, does that squareness need to be an even number, or a specific number?
  2. When I import my map, I see the lines from the tiles UE used. If I select 2x2, I see raised lines running through my map. What do I need to do so that UE doesn’t display the tile lines? They don’t look very good. (I already applied a blur to the heightmap itself, and the grid is very apparent, so these are definitely coming from UE, not the heightmap. )