Why are big chunks of Sam Francisco missing (eg around the bridge) missing from the example?
python create_map_poster.py -c "San Francisco" -C "USA" -t sunset -d 10000
-d should be approx. 10k to 14k given the size of the city. You can give it a shot.
Those smooth chunks are all (mostly) public park land. Known as Presidio and part of the Golden Gate National Recreation Area.