Baked lightmapA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
See in Glossary UVs are per-mesh: all instances of the same meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary share the same baked lightmap UVs. Unity can generate these UVs when you import a model, or you can provide your own data.
Unity stores baked lightmap UVs in the mesh in the Mesh.uv2 channel. This channel maps to the TEXCOORD1 shaderA program that runs on the GPU. More info
See in Glossary semantic and is commonly called UV1.
When you enable Baked Global IlluminationA group of techniques that model both direct and indirect lighting to provide realistic lighting results.
See in Glossary and a MeshRenderer receives its global illumination from lightmaps, Unity uses the data in the Mesh.uv2 channel to correctly map the baked lightmaps to the mesh.
Note: If you want to use Mesh.uv2 for another purpose in a given mesh, you must ensure that all MeshRenderer components that use the mesh receive global illumination from light probesLight probes store information about how light passes through space in your scene. A collection of light probes arranged within a given space can improve lighting on moving objects and static LOD scenery within that space. More info
See in Glossary rather than lightmaps. Configure this in the Mesh Renderer component Inspector, or via the MeshRenderer.receiveGI API.
For more information, refer to Generating lightmap UVs.