----------------------------Original message---------------------------- >From: Roger Wheate <[log in to unmask]> >Subject: Map resolution >To: Multiple recipients of list MAPS-L <[log in to unmask]> > >----------------------------Original message---------------------------- > >Can anyone remind me what is the 'resolution' of a 1:50,000 map, or >whether there is a general formula based on scale. For example if one is >using scanned / digital data associated with a certain map scale, at what >point is using smaller size pixels in raster cartography redundant in >that the pixel detail exceeds the quality of the original data. > >Roger Wheate >UNBC As I recall, the USGS states that features on its 1:25,000 sheets are, at best, placed to 1/30 to 1/50 th of an inch for certain features. Add to this the factors of instability of paper media, 150 dpi would be more than adequate. But to retain image line/lettering detail, probably 300 dpi should be used. Gerald (Jerry) I. Evenden Internet: [log in to unmask] voice: (508)563-6766 Postal: P.O. Box 1027 fax: (508)457-2310 N.Falmouth, MA 02556-1027