i have imported many objs in the CityEngine scene.Can i combine objs in one layer or one mdb
select two layers, then "merge layers" via right-mouse button menu
or as an alternative, you can also select the object in the viewport, then press ctrl-x (cut), select the layer in the scene editor and press ctrl-c (copy). Means you can use copy-cut-paste to move objects between layers.
Retrieving data ...