If the sectors don't really have the coordinate system, which coordinate system the object use in the sectors, world space coordinates or camera space coordinates?
Well obviously objects use world space coordinates. Camera space coordinates don't make sense here.
Can i creat a lot of sectors, replicate them and use portal to connect them in different place, in a word, to use them many times in the same world map to compose a level to the game? For example, assume i create sector01, sector02 and use portal to connect them like this:
sector01 | portal01 | sector02 | portal02 | sector01 | portal03| sector01| portal04|……
for this i want to ues them in a labyrinth to represent the same terrain, can i do it like this? Is it right?
You can do all kinds of interesting tricks here but remember that 'sector01' is always the same sector. So if you use it multiple times like you do above you essentially end up in exactly the same sector with exactly the same coordinate system.