GI bake lights + Atlas texture ?

Unity Engine
1

hi …
just toknow how make an atlas texture …
when use bake option light mapping on unity 2017 please.
.
i make almost a perfect GI bake mapping but unity make 200 small textures.
please how can i make atlas textures insted 200 textures please
i will apreciate somuch any comment or help
thanks.

2

please any help ?