Version: Unity 7.0 Alpha (7000.0)
Language : English
Unity Compute Light Baker
Troubleshooting baked lightmaps

Group GameObjects together in a lightmap with Baked Tags

The two images below shows two views of the same Scene:

In this example, all the GameObjects have the same Baked tag, and Unity stores all lighting data in one atlas. In this example, one GameObject is assigned a different Baked tag, and Unity creates a separate lightmap for it.

Unity Compute Light Baker
Troubleshooting baked lightmaps