[Proj] WGS84 to Minnesota State Plane South
Gerald I. Evenden
geraldi.evenden at gmail.com
Thu Jan 3 12:01:46 EST 2008
On Thursday 03 January 2008 11:10 am, Arno Gerretsen wrote:
> Thanks Anthony, your proj string helped me solving the problem. It
> turned out to be a problem with the meter to feet conversion. In the
> stirng I used I had tried both +units=ft and +units=m with my own
> multiplication by 0.3048 to get meters. Now it turns out that is where
> the problem was, I had to use 0.3048006 as you did. I did not know there
> was a different between a foot and a US survey foot.
Indeed, there IS a difference as I well know when I was first putting together
projection software in the '80 and spent many an hour trying to reconcile the
differenced between an earlier version of proj and gctp. FINALLY, I
discovered a mention of the difference between the foots in Snyder's
manual---one lonely sentence!
> But it seems that the proj library also uses the 0.3048 factor when I
> set the units to feet, is that what it is supposed to do?
Old standard USGS 'proj -lu' and current lproj lists units conversions
understood internally. Thus for the various foot conversions you will see
m 1. Meter
ft 0.3048 International Foot
us-ft 0.304800609601219 U.S. Surveyor's Foot
ind-ft 0.30479841 Indian Foot
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist
More information about the Proj