Does Terrain size matter if the game scale is big?

Hi,

I’m using Unity’s units to match real world meters so my objects are around 100-200 meters in size usually. My terrain has a width of around 15,000 and length around 10,000, with a height of 600. My terrain heighmap resolution is still small around 513. So everything behaves like a small terrain as it’s all scaled appropriately to meter units.

  1. Does it make any difference to have such a big terrain or are those units pretty much just arbitrary? Is there any sort of performance concern I should have (especially for mobile)?

  2. Are there any benefits to shrinking everything down to 1/10th or 1/100th scale? or breaking up the terrain into smaller terrains?

You may want to scale down your unit system because of floating-point precision issues : floating point are loosing precision when you get away from zero and jitter appears.

Kerbal Space Program did a great video on this : video link

I know two solutions for this : scale down your world or use a floating origin.

Breaking your big terrain into smaller chunk can be interesting if you want more details (by using bigger heightmap/texture resolutions for smaller terrains).

Thanks Ambro. I don’t think I have any floating point issues, as far as I understand those only come into play on the very large scale (ie: in the millions of units) rather than the thousands. Do you know if the terrain length/width have any sort of memory or processing impact if they are large? I’m not clear on whether a width of 10,000 uses 10x the memory that a width of 1000 does…