TIP: When you're using satellite images for your terrain and it looks quite pixelated, it often helps if you add a 2nd (tiling) detail texture. For this to work, you'll need to apply different UV coordinates to the 2nd texture layer in your modelling application, so that it tiles across the full extent of the terrain object. After importing the terrain object in Lumion, you'll then need to add a Lightmap material and load the detail texture in the 2nd slot (see the screenshot below).
(The copyright holder of this terrain texture is the US Geological Survey:
http://www.usgs.gov/)