I already answered this on the Map-Making for Games G+ community... same answer, though.
Question time Community!
I'm developing a world map for a good size company. They are currently using it for a 8.5" x 11" booklet. Later it will be used for a full size fold out map.
My question is what size would you work at and what DPI? I usually work at 50% for the hand drawn part and scan at 300 DPI, then do my inks in photoshop.
With that said I want to hand ink this map so what should I do the original size at? And what DPI would you scan it in at?
I always try to paint larger than the final size, if possible. Do you know the size of the poster? If not, I'd say go as big as your scanner can handle. If you have access to an A3 scanner, you can paint in A2 or even A1 with some stitching-together in PS. Of course depends on the detail level of the map though, maybe you won't need that big.
As for resolution, similar answer: as big as possible. 300 DPI is the minimum for good quality printing, but if your scanner and computer allows it, there are no downsides to taking even sharper scans (except slowing down PS ).
Thank you for all the answers and to you as well Gameprinter. I'm waiting to hear the final size right now but I'm guessing the standard fold out poster size.
Even knowing the DPI to pixel ratio my question is can I draw it at 50% and if the piece I scan in is at a good enough DPI? Then blow it up in photoshop to do color work?
Honestly if the original is 50% it's intended size, it should look fine enlarged. Just do all your linework with the original, that is, if you do any linework to the enlarged version as finishing touches your pen lines will be significantly larger than the original. You don't want varying pen line widths. As long as your not enlarging it more than 100% of original, it shouldn't be a problem. I always draw a map at 100% scale or more of the final map, but that's just my preference.
This is something I am also wondering as I'm trying to take a 30x20 image and enlarge it to 72x48.