Here's my most recent finished map. And a detail of it, with frontiers of Hyrule's Kingdom.
100% Photoshop, about 12 hours of work.
Original size: 7677*5906px (= 65*50 cm, 300 dpi)
If someone wants to know how I proceeded, a tutorial is available (in french only).
And the map of Hyrule.
EDIT Now the complete map is on a more interesting size.