On Lumion Support page under Exporters there is now a new DWG to Lumion Bridge. This Bridge is for Lumion 6 users only and allows you to import DWGs directly. In the past you could import DWG file but the material etc did not come through only the geometry did. Anyway I tested the new bridge and it works very well as most of the standard materials added in my little model is shown in Lumion 6. This is key development for users that have Revit LT which cannot export to DAE format as so has to use a DWG export from Revit. These users can now use the DWG Bridge and get Autodesk materials into Lumion. Just note that with Lumion 6 it restricts you from importing DWGs if you do not have the DWG Bridge installed.
Ok so here is the process:
Visit the Lumion Support page and look for the DWG to Lumion Bridge : http://lumion3d.com/support
Clicking this link takes you to the DWG to Lumion Bridge page. http://lumion3d.com/dwg-to-lumion-bridge/
Click the MSI file and downloaded it. You notice that the file is rather large ( 250MB ) I think the reason for the large size is as this is an addon to Lumion in contains all the Autodesk Materials and once installed as an addon to Lumion 6 it recognizes the Autodesk Materials coming in through DWG format. Run the file to install the addon.
Now go to AutoCAD and create a 3D DWG with materials attached. Save the file.
Open Lumion and open any empty scene. Import the DWG file.
Notice the glass did not come through. I just had to add the glass material.