World Machine resolution and scale?

Hi! 20Km is the biggest size you can have on ue4 right? if that´s correct i wonder what my settings/resolution on world-machine would be?
If it is not correct i would like to know what the (BIGGEST) landscape you can play and make in UE4. <3

Thanks for reply <3

Heightmaps by definition don’t have a real world “km” area value.
They are a pixel or sample value, such as 2017x2017 pixels.
They only relate to an area such as km as soon as you apply a distance or spacing value to the terrain vertices that use the heightmap.
So a 2048x2048 heightmap with a vertex spacing of 1280 (I think, check my math) results in a terrain of 20km square.
But so does a 512x512 heightmap with a vertex spacing of 5120 result in a terrain of 20km square.
TerreSculptor can create heightmaps up to a size of 65536x65536 (typically ~46kx46k before running out of memory), so that would require even a smaller vertex spacing to get a 20 km square terrain.

You should choose the heightmap resolution based on a number of factors including the target computer performance and final resulting content file size, and not by the number of square km that it gives you.

That depends entirely on the target computer hardware.
If it is a dual core i3 with 4GB RAM and a small basic video card, then the “biggest” Landscape is going to be quite small.
For example a heightmap of 1009x1009 may be the largest you can get to perform well in a smaller older computer.

You should choose the heightmap resolution based on a number of factors including the target computer performance and final resulting content file size, and not by the number of square km that it gives you.