Level Connection and Loading Screens

Hi. I ve noticed lots of level loading even if the entire game world is small.
You redirected onto a new level after every few doors you pass.
So why is it done? Because of performance? How big my map can be?
Why GTA V or witcher have big locations, with good graphics but without loading screens then? Is it “optimisation”? What’s optimisation? Or is it loading
while i am playing?

Also. Ive already created a medium sized level. Can I divide it into 2 levels?
Or I can only create 1st level, then 2nd, then connect them?

Thank you

Look at Streaming Levels. This can be sync or async.

GTA V also uses some form of level streaming. As long as you are walking/driving around you wont notice anything. When switching players some time is needed to transfer you, this is because of loading that part of the map.

Okay so what’s async and sync streaming? Still can I divide my level into smaller levels?
How the logic of unreal engine works in level connection? Thank you.

async = loading while you can still play
sync = loading while everything blocks(everything on the screen stands still)

async is slower because the game must keep on running

You can read a bit more here: Volumes Reference | Unreal Engine Documentation (search for ‘streaming’). Also search on this forum and on https://docs.unrealengine.com with the key words streaming levels.

In the Content Examples project(available in the Learning Tab in the Launcher) there is an example map with streaming volumes, its called Level_Streaming under the map Maps. Run that map, read some topics/docs and things will become much more clear!

Thank you very much.