Do you need a lightmap in the second chan?

Do you need to have a light map in the second channel of any model if for example they are simple planes for walls?

Second, when you say “do not overlap” does that make do not over lap with the first channel, or do not overlap in general in the uv channel with other faces?

  1. when you use static lightning you will need a lightmap for every mesh → when the ue4 doesnt find a lightmap, it will take the 1st uv channel (so in a case of a plane you normally dont have to create one)
  2. This is just for the 2nd uv/lightmap → UDK: Lightmapping Basics and 18 Important Principles for Creating and Using Lightmaps for UDK