Call me a newb, but I honestly don't know. (shrug) All I could say is enough to allow for a 200-400% zoom without rendering the imagine too foggy. I understand that probably doesn't help much. Sorry. The best example I can think to describe it is Aventhar's album. The world map is great of understanding layout and scale, but you lose a lot of resolution zooming to each continent, so where s/he has done Galinorn as it's own map works great. You can get pretty close without losing a lot of resolution in the rivers and mountains. That's my biggest concern - well defined rivers - I hate it when I go in for a closer look and the river ceases to have banks and becomes a wide, blue smudge.