Does Unity have a map size limit and if there is what is the limit? Is there a way to work around it? I am making a open world zombie survival world and I want to make a really big map. Thanks!
The limit for a single map is 2000, you can merge them until your pc allows you. I have copied a fully painted terrain around 4048~ times and everything was working properly. The rendering view ends at 2km. The terrains area does't affect performance, the LOD does, grass etc.
Somebody has actually made a map which was the size of Alaska, was funny to watch videos of people who tried running across the map. The only problem in creating a persistant world is the fact that when there are two terrains next to each other. They can not be edited at once, this creates many places for the holes in the ground where players could fall. In order to avoid this, you'd need to get a seamless terain plugin that allows you to merge terrains so that their lelevation level is the same.
To work around the limit you should use 4 terrains that are 2km/2km instead of a 4km/4km.
Search the terrain plugin directory on the unity asset store.
FYI. Don't make the world too big. A standard game human character will need over 10 minutes of running to cross 2 kilometres.
According to most of the threads on Unity Answers there is no effective limit. You're limited only by computer accuracy of floating points, memory and the amount of objects you can have. That being said - you should consider cunking your scenes up for the sake of organization. Maintaining one big scene might get really monstrous, really quickly.
For such a big map, specially if you're planning on some kind of vehicles, take into account floating point errors.
What I mean is, if you get too away from x:0,y:0,z:0, the floating point errors will be enough to make physics shake, and many other bad things. This can be fixed by simply moving the entire world. Basically moving the whole map, making sure your position is at 0,0,0.
A rule of thumb is that for anything bigger than 5km for safety you should do corrections. This is probably way under the "game-killing physics" distance, but it's better to be safe.