A VROPT file contains pre-calculated optical properties . Unlike a standard transparent material, an optics file simulates how light bends, scatters, and absorbs as it passes through an object.
You don't need to download a .vropt file separately. Instead, search for and the .vropt will be auto-generated on your first render. vropt file interior new download sketchup
: High-quality interior models that include complete .visopt (older) or .vropt (newer) setting files. A VROPT file contains pre-calculated optical properties