----------------------------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