I've seen this at multiple airports, and now I'm experiencing this problem for the second time with an airport I build myself. Whenever you set the material type of a taxiway in WorldEditor to Dirt, then blow it through TerraGear, you end up with a rock-like texture in FlightGear, which is very annoying. Dirt runways do render fine. Is there anything I could be doing wrong, or is TerraGear / FlightGEar broken ? I am using 2020.4.0, but I experienced the same problem with 2020.3.6.
Another problem with self-built airports is that they sometimes have high walls in the terrain at the boundary - also rather ugly, but this problem I only have with self-built airports. How to fix that ? I have --max-slope=1 for genapts850, and tried nudge=0, nudge=1 and nudge=100 on both genapts and tg-construct.