@rich o brien said:
The SVG is used to open in an image editor to paint your textures over the UV islands.
Moving the islands in the SVG does not change the UV positions of the 3D mesh.
The reason we export to SVG is that the SVG is scalable to any size as long as it maintains the ratio.
SketchUp doesn't not import SVG files. The export to SVG is purely to allow you to paint the islands with the textures you need in an app of your choice.
Thanks Rich,
Is there a way to save the UV unwrap layout apart from saving the skp?
Now I have a great 4k map drawn in Substance Painter but I can't get it back to SU.
And I can't import the DAE (export as sketchfab from SP) inside 3dsmax neither as there are normal tangent issues and no surfaces are generated...
All I can try now - if I understand correctly- is to replace the UV islands on the previous layout in WrapR thanks to the svg after having it converted in Photoshop or Illustrator.
Is it possible to have a better unwrapping algorithm someday? And some in depth tutorials too 
Thanks for the plugin anyway, it was a missing chain in the workflow!

