UVbyBitmap

"UVbyBitmap modify the size of the clusters UV according to the size in pixels of bitmaps associed to the material. This step restore the connection which exist between various bitmaps and apply it to the needed UVW channel. It accepts standard materials and multi/Sub-Object materials including standard materials. In this case the various ID are automatically separated from the others. It also includes a function to copy a whole UV channel.

Usage:
1 - Select the objects which will receive the lightmap.
2 - Adjust the channel which will receive the lightmap under the group 'channel'.
3 - If It's necessary check 'copy from' and select the right channel.
4 - Click on 'Set UV's Size'.

Known limitations:
- Only polys or meshes are supported. Others objects like primitives receive a modifier Edit Mesh or Edit Poly.
- Objects must have a material 'Standard' or 'multi/Sub-Object' which contains several materials 'Standard'.
- Objects must have an bitmap in the diffuse of the material.

If you encounter bugs or problems that I am not aware of