I am interested in discussing algorithms:

First of all,

  1. how to combine SRTM and OSM data to get correct elevation profiles for 3D roads, building, forests
    then
  2. how to draw roofs of Subtype 9
  3. how to automatically position windows and doors for buildings
  4. how to realistically represent millions of trees

Also I suggest to discuss a collection of realistically looking textures for POV-Ray-based applications (e.g. a texture for asphalt roads, tracks, footways, water, buildings, etc)