[Proj] Discovery: libproj4 stmerc = French Gauss-Laborde
Gerald I. Evenden
gerald.evenden at verizon.net
Sun Jun 18 21:28:13 EDT 2006
The French Transverse Mercator (NT/G 76 publication) is now in libproj4 on my
desk---+proj=ftmerc . It extends well beyond the 5 degree limit of tmerc but
starts to fail with low latitudes and extended longitudes beyond 40 degrees.
It compares with the German online site within +-0.2mm. Unfortunately the
German site does not display major axis and ellipsoid parameters so it is
possible that errors in this range are due to minor variations of these
figures and/or how they are specified.
ftmerc has forward and inverse mode.
This release of libproj4 will not be on my web site until the documentation is
brought up to date and the new output formating routine is installed.
If anyone wants a prelim copy of proj_ftmerc.c and proj_psi.c, I can email
I am not going to do anything at the moment with the Dozier method.
Jerry and the low-riders: Daisy Mae and Joshua
"Cogito cogito ergo cogito sum"
Ambrose Bierce, The Devil's Dictionary
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