Generating roads from OpenStreetMap

1. Line up the satellite pictures and load the tile's terrain heights.
2. Select the tile.
3. In the satellite window, choose Preview roads for selected tile.
4. Check the preview against the imagery, then choose Build previewed roads. Ctrl+Z undoes the whole lot.

It uses OpenStreetMap's mapped centre lines and road tags. In Great Britain, it also checks OS Open Roads for gaps.

#What it handles

One-way streets, roundabouts, footways, car-park aisles and gravel and dirt tracks. A car park or bus platform mapped as a single closed outline inside the tile can get a surface too.

#What it doesn't

Bridges, tunnels, buildings and complex areas with holes are outside its scope. Some short or conflicting approaches are skipped. The summary at the end lists anything skipped and any junction ends to check.