Hi, FYI. I have added support for the command in the COLLADA file that tells if the material is double sided or not (this is a Google Earth specific material parameter). This means that with almost all KMZ files you will now get all materials as double sided. This is how it is designed in Google Earth I guess. You can try to turn it off, but I have seen quite some models that need to have double sided enabled to get all polygons facing correctly.