A commenter on yesterday’s post asks if I know of any programs that will convert a list of coordinates in degree-minute-second format to decimal degrees. Haven’t tried it, but Zonums Software has a free Excel macro called Ectrans that will supposedly convert a spreadsheet list of coordinates in degree-minute second format to decimal degrees (and vice versa), or one set of coordinates at a time manually. It also converts spreadsheet coordinate lists from lat/long to UTM and back again. If you don’t have Excel, it might work with OpenOffice, since I hear rumors that OpenOffice may support some VBA macros.
Zonums also has online decimal-DMS converters for converting one point at a time, adding them to a text box that can be copied and pasted as a CSV spreadsheet file; points can also be plotted on a Google Maps interface. There are also online lat/long to UTM converters accessible from the same page, but they don’t appear to be working currently.
From comments in yesterday’s post, Dylan Beaudette describes how to do it using FWTools (command-line, run away! ;-):
1. convert DD -> DMS:
cs2cs +proj=latlong +datum=NAD83 +to +proj=latlong +datum=NAD83
2. convert DMS -> DD
cs2cs -f “%.6f” +proj=latlong +datum=NAD83 +to +proj=latlong +datum=NAD83
If you invoke the command as listed above (without reference to a data stream) you will get an interactive prompt. This approach is a lot more useful when you have a file full of coordinates, or a stream of coordinates:
cs2cs +proj=latlong +datum=NAD83 +to +proj=latlong +datum=NAD83 < DD_coords.txt > DMS_coords.txt
Also from the comments, for programmers, Aron Rubin posts code for a C function that will do the conversion.